/* ==========================================================================
   MuscleMind PWA - Global Stylesheet
   Version: 1.0.0
   Description: Comprehensive production-quality CSS for MuscleMind Anatomy
   ========================================================================== */

/* ==========================================================================
   1. Design System (CSS Custom Properties)
   ========================================================================== */

:root {
  /* Fonts */
  --font-heading: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";

  /* ── Pure Black Premium Theme ── */

  /* Primary Accent — Electric Blue */
  --color-primary: #3B82F6;
  --color-primary-light: #60A5FA;
  --color-primary-dark: #1D4ED8;
  --color-primary-rgb: 59, 130, 246;

  /* Secondary Accent — Emerald */
  --color-secondary: #10B981;
  --color-secondary-light: #34D399;
  --color-secondary-dark: #059669;

  /* ── Black Surfaces ── */
  --color-bg: #000000;          /* Pure black page background */
  --color-surface: #0A0A0A;     /* Near-black navbar / panels */
  --color-card: #111111;        /* Dark charcoal cards */
  --color-card-hover: #161616; /* Slightly lighter on hover */

  /* ── Typography ── */
  --color-text: #F1F5F9;           /* Bright white text */
  --color-text-secondary: #A1A1AA; /* Zinc-400 secondary */
  --color-text-muted: #52525B;     /* Zinc-600 muted */

  /* ── Borders ── */
  --color-border: #1F1F1F;         /* Barely visible black borders */
  --color-border-hover: #3B82F6;   /* Blue on focus */

  /* Status Colors */
  --color-danger: #F87171;
  --color-warning: #FBBF24;
  --color-success: #34D399;
  --color-info: #60A5FA;

  /* Status Colors (RGB) */
  --color-danger-rgb: 248, 113, 113;
  --color-warning-rgb: 251, 191, 36;
  --color-success-rgb: 52, 211, 153;
  --color-info-rgb: 96, 165, 250;

  /* ── Shadows (Deep for black surfaces) ── */
  --shadow-sm: 0 1px 3px 0 rgba(0,0,0,0.6);
  --shadow-md: 0 4px 12px -2px rgba(0,0,0,0.7), 0 2px 6px -1px rgba(0,0,0,0.5);
  --shadow-lg: 0 10px 25px -4px rgba(0,0,0,0.8), 0 4px 10px -2px rgba(0,0,0,0.6);
  --shadow-xl: 0 20px 40px -6px rgba(0,0,0,0.9), 0 8px 16px -4px rgba(0,0,0,0.7);
  --shadow-inner: inset 0 2px 6px 0 rgba(0,0,0,0.5);
  --shadow-glow: 0 0 20px rgba(59,130,246,0.4), 0 0 40px rgba(59,130,246,0.15);
  --shadow-glow-green: 0 0 20px rgba(52,211,153,0.4), 0 0 40px rgba(52,211,153,0.15);

  /* Border Radius */
  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;

  /* Spacing */
  --spacing-1: 0.25rem;
  --spacing-2: 0.5rem;
  --spacing-3: 0.75rem;
  --spacing-4: 1rem;
  --spacing-5: 1.25rem;
  --spacing-6: 1.5rem;
  --spacing-8: 2rem;
  --spacing-10: 2.5rem;
  --spacing-12: 3rem;
  --spacing-16: 4rem;
  --spacing-20: 5rem;
  --spacing-24: 6rem;

  /* Z-index layers */
  --z-negative: -1;
  --z-elevated: 1;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-fixed: 300;
  --z-overlay: 400;
  --z-modal: 500;
  --z-popover: 600;
  --z-toast: 700;
  --z-tooltip: 800;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-bounce: 500ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
}


/* ==========================================================================
   2. Global Reset & Base
   ========================================================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.5;
  scroll-behavior: smooth;
  text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  background-color: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
}

::selection {
  background-color: var(--color-primary);
  color: #FFFFFF;
}

::-moz-selection {
  background-color: var(--color-primary);
  color: #FFFFFF;
}

/* Custom Scrollbar for Webkit */
::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-track {
  background: var(--color-bg);
}

::-webkit-scrollbar-thumb {
  background-color: var(--color-border);
  border-radius: var(--radius-full);
  border: 2px solid var(--color-bg);
}

::-webkit-scrollbar-thumb:hover {
  background-color: var(--color-text-muted);
}

/* Custom Scrollbar for Firefox */
* {
  scrollbar-width: thin;
  scrollbar-color: var(--color-border) var(--color-bg);
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

input,
button,
textarea,
select {
  font: inherit;
  color: inherit;
}

button {
  background: none;
  border: none;
  cursor: pointer;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
}

ul,
ol {
  list-style: none;
}

/* ==========================================================================
   3. Typography
   ========================================================================== */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
  margin-bottom: var(--spacing-4);
}

h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  letter-spacing: -0.01em;
}

h3 {
  font-size: clamp(1.25rem, 2vw, 1.75rem);
}

h4 {
  font-size: clamp(1.1rem, 1.5vw, 1.5rem);
}

h5 {
  font-size: 1.25rem;
}

h6 {
  font-size: 1rem;
}

p {
  margin-bottom: var(--spacing-4);
  color: var(--color-text-secondary);
}

strong, b {
  font-weight: 600;
  color: var(--color-text);
}

.text-gradient {
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-image: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  display: inline-block;
}

.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-text-secondary); }
.text-muted { color: var(--color-text-muted); }
.text-danger { color: var(--color-danger); }
.text-success { color: var(--color-success); }
.text-warning { color: var(--color-warning); }

/* ==========================================================================
   4. Layout Components
   ========================================================================== */

/* --- Navbar --- */
.navbar {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  height: 64px;
  background-color: rgba(0, 0, 0, 0.85); /* Pure black fallback */
  background-color: color-mix(in srgb, var(--color-surface) 90%, transparent);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  z-index: var(--z-sticky);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.navbar-container {
  max-width: 1400px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--spacing-6);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  text-decoration: none;
}

.nav-logo {
  font-size: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: white;
}

.nav-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-text);
  letter-spacing: -0.01em;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--spacing-1);
}

.nav-btn {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
  position: relative;
}

.nav-btn:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.nav-btn svg {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.sidebar-toggle {
  display: none;
}

/* --- Sidebar --- */
.sidebar {
  position: fixed;
  top: 64px;
  left: 0;
  width: 280px;
  height: calc(100vh - 64px);
  background-color: var(--color-surface);
  border-right: 1px solid var(--color-border);
  z-index: var(--z-fixed);
  transition: transform var(--transition-normal) ease-in-out;
  display: flex;
  flex-direction: column;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-4) var(--spacing-5);
  border-bottom: 1px solid var(--color-border);
}

.sidebar-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
}

.sidebar-close {
  display: none;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  align-items: center;
  justify-content: center;
}

.sidebar-close:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.sidebar-close svg {
  width: 20px;
  height: 20px;
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-2);
}

.sidebar-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  padding: 10px var(--spacing-4);
  border-radius: var(--radius-md);
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: all var(--transition-fast);
  margin-bottom: 2px;
  cursor: pointer;
}

.sidebar-item:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.sidebar-item.active {
  background-color: rgba(var(--color-primary-rgb), 0.1);
  color: var(--color-primary);
  font-weight: 600;
}

.sidebar-icon {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background-color: var(--color-bg);
  font-size: 1rem;
  flex-shrink: 0;
  transition: background-color var(--transition-fast);
}

.sidebar-item:hover .sidebar-icon {
  background-color: var(--color-surface);
  box-shadow: var(--shadow-sm);
}

.sidebar-item.active .sidebar-icon {
  background-color: var(--color-surface);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.sidebar-label {
  font-size: 0.95rem;
  flex: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar-number {
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-weight: 500;
  background-color: var(--color-bg);
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

.sidebar-item.active .sidebar-number {
  background-color: var(--color-surface);
  color: var(--color-primary);
}

.sidebar-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(2px);
  z-index: calc(var(--z-fixed) - 1);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
}

/* --- Main Content --- */
.main-content {
  flex: 1;
  width: 100%;
  min-height: calc(100vh - 64px);
  padding: var(--spacing-6);
  transition: margin-left var(--transition-normal) ease-in-out;
}

.main-content-inner {
  max-width: 1100px;
  margin: 0 auto;
}

/* --- Panels (Progress) --- */
.panel {
  position: fixed;
  top: 64px;
  right: -420px; /* Initially hidden */
  width: 380px;
  max-width: calc(100vw - 32px);
  height: calc(100vh - 64px);
  background-color: var(--color-surface);
  z-index: var(--z-fixed);
  transition: right var(--transition-normal) cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: var(--shadow-xl);
  border-left: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
}

.panel.active {
  right: 0;
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-5);
  border-bottom: 1px solid var(--color-border);
}

.panel-title {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
}

.panel-close {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  background-color: var(--color-bg);
  transition: all var(--transition-fast);
}

.panel-close:hover {
  background-color: var(--color-danger);
  color: white;
  transform: rotate(90deg);
}

.panel-content {
  flex: 1;
  padding: var(--spacing-4);
  overflow-y: auto;
}

/* ==========================================================================
   5. Hero Section
   ========================================================================== */

.hero {
  padding: var(--spacing-20) var(--spacing-6);
  text-align: center;
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-2xl);
  background: linear-gradient(180deg, var(--color-surface) 0%, var(--color-bg) 100%);
  margin-bottom: var(--spacing-12);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at center, rgba(var(--color-primary-rgb), 0.05) 0%, transparent 70%);
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background-color: rgba(var(--color-primary-rgb), 0.1);
  color: var(--color-primary);
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: var(--spacing-6);
  border: 1px solid rgba(var(--color-primary-rgb), 0.2);
  box-shadow: 0 0 10px rgba(var(--color-primary-rgb), 0.1);
  animation: slideDown 0.6s ease-out;
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: var(--spacing-5);
  color: var(--color-text);
  animation: slideUp 0.8s ease-out;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto var(--spacing-8);
  line-height: 1.6;
  animation: slideUp 1s ease-out 0.1s both;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-4);
  flex-wrap: wrap;
  animation: slideUp 1s ease-out 0.2s both;
}

/* ==========================================================================
   6. Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all var(--transition-fast);
  cursor: pointer;
  text-decoration: none;
  border: 2px solid transparent;
  line-height: 1.2;
}

.btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.btn:active {
  transform: scale(0.98);
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
}

.btn-primary {
  background-color: var(--color-primary);
  color: #FFFFFF;
  box-shadow: 0 4px 10px rgba(var(--color-primary-rgb), 0.3);
}

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  box-shadow: 0 6px 15px rgba(var(--color-primary-rgb), 0.4);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: transparent;
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-secondary:hover {
  background-color: var(--color-primary);
  color: #FFFFFF;
  box-shadow: 0 4px 10px rgba(var(--color-primary-rgb), 0.2);
}

.btn-ghost {
  background-color: transparent;
  color: var(--color-text-secondary);
}

.btn-ghost:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.btn-danger {
  background-color: var(--color-danger);
  color: #FFFFFF;
}

.btn-danger:hover {
  background-color: #DC2626;
  box-shadow: 0 4px 10px rgba(var(--color-danger-rgb), 0.3);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 16px 32px;
  font-size: 1.1rem;
  border-radius: var(--radius-lg);
}

.btn-icon {
  padding: 8px;
  border-radius: var(--radius-md);
  width: 40px;
  height: 40px;
}

.btn svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ==========================================================================
   7. Body Part Cards Grid
   ========================================================================== */

.body-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--spacing-5);
  padding: var(--spacing-8) 0;
}

.body-card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  padding: var(--spacing-6);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  cursor: pointer;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: inherit;
}

.body-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg), 0 0 20px rgba(59,130,246,0.15);
  border-color: rgba(59,130,246,0.5);
}

.body-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.body-card:hover::before {
  opacity: 1;
}

.body-card-number {
  position: absolute;
  top: var(--spacing-3);
  right: var(--spacing-4);
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-weight: 700;
  letter-spacing: 0.05em;
}

.body-card-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background-color: rgba(var(--color-primary-rgb), 0.08);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
  margin-bottom: var(--spacing-4);
  transition: transform var(--transition-bounce), background-color var(--transition-normal);
}

.body-card:hover .body-card-icon {
  transform: scale(1.1);
  background-color: var(--color-primary);
  color: #FFFFFF;
}

.body-card-name {
  font-size: 1.25rem;
  font-weight: 700;
  font-family: var(--font-heading);
  margin-bottom: var(--spacing-2);
  color: var(--color-text);
  transition: color var(--transition-fast);
}

.body-card:hover .body-card-name {
  color: var(--color-primary);
}

.body-card-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
  flex: 1;
}

.body-card-meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  margin-top: var(--spacing-4);
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

.body-card-arrow {
  position: absolute;
  bottom: var(--spacing-4);
  right: var(--spacing-4);
  color: var(--color-primary);
  opacity: 0;
  transform: translateX(-10px);
  transition: all var(--transition-normal);
}

.body-card-arrow svg {
  width: 20px;
  height: 20px;
}

.body-card:hover .body-card-arrow {
  opacity: 1;
  transform: translateX(0);
}

/* ==========================================================================
   8. Region Header & Section
   ========================================================================== */

.region-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  margin: var(--spacing-10) 0 var(--spacing-5);
}

.region-header h2 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin: 0;
}

.region-header::after {
  content: '';
  flex: 1;
  height: 1px;
  background-color: var(--color-border);
}

.section {
  margin-bottom: var(--spacing-12);
}

.section-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  margin-bottom: var(--spacing-6);
}

.section-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background-color: rgba(var(--color-primary-rgb), 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
  flex-shrink: 0;
}

.section-icon svg {
  width: 20px;
  height: 20px;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0;
  color: var(--color-text);
}

.section-desc {
  color: var(--color-text-secondary);
  margin-top: 4px;
  font-size: 0.95rem;
}

/* ==========================================================================
   9. Breadcrumb
   ========================================================================== */

.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--spacing-2);
  flex-wrap: wrap;
  padding: 0 0 var(--spacing-6);
  font-size: 0.9rem;
  font-weight: 500;
}

.breadcrumb-item {
  display: flex;
  align-items: center;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.breadcrumb-item a {
  color: var(--color-text-secondary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 4px;
}

.breadcrumb-item a:hover {
  color: var(--color-primary);
}

.breadcrumb-item a svg {
  width: 16px;
  height: 16px;
}

.breadcrumb-separator {
  color: var(--color-text-muted);
  margin: 0 4px;
}

.breadcrumb-item.active {
  color: var(--color-text);
  pointer-events: none;
}

/* ==========================================================================
   10. Cards, Accordion, Tabs, Data Table, Tags
   ========================================================================== */

/* --- Generic Card --- */
.card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  margin-bottom: var(--spacing-6);
  transition: box-shadow var(--transition-fast);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

.card-header {
  padding: var(--spacing-5) var(--spacing-6);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-3);
  background-color: rgba(255,255,255,0.01);
}

.card-title {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 600;
}

.card-body {
  padding: var(--spacing-6);
}

.card-footer {
  padding: var(--spacing-4) var(--spacing-6);
  border-top: 1px solid var(--color-border);
  background-color: var(--color-bg);
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: var(--spacing-3);
}

/* --- Accordion --- */
.accordion {
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  background-color: var(--color-card);
  overflow: hidden;
}

.accordion-item {
  border-bottom: 1px solid var(--color-border);
}

.accordion-item:last-child {
  border-bottom: none;
}

.accordion-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--spacing-4) var(--spacing-5);
  background-color: transparent;
  border: none;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  transition: background-color var(--transition-fast);
  text-align: left;
}

.accordion-header:hover {
  background-color: var(--color-bg);
}

.accordion-header:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
}

.accordion-title {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
}

.accordion-chevron {
  width: 20px;
  height: 20px;
  transition: transform var(--transition-normal);
  color: var(--color-text-muted);
  flex-shrink: 0;
}

.accordion-item.active .accordion-header {
  color: var(--color-primary);
  background-color: rgba(var(--color-primary-rgb), 0.02);
}

.accordion-item.active .accordion-chevron {
  transform: rotate(180deg);
  color: var(--color-primary);
}

.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow) ease-in-out;
}

.accordion-inner {
  padding: 0 var(--spacing-5) var(--spacing-4);
  color: var(--color-text-secondary);
}

/* --- Tabs --- */
.tabs {
  margin-bottom: var(--spacing-6);
}

.tabs-header {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--color-border);
  overflow-x: auto;
  scrollbar-width: none;
}

.tabs-header::-webkit-scrollbar {
  display: none;
}

.tab-button {
  padding: 12px 20px;
  background-color: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  font-weight: 500;
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.tab-button:hover {
  color: var(--color-text);
  background-color: rgba(255,255,255,0.04);
}

.tab-button.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
  font-weight: 600;
}

.tab-panel {
  display: none;
  padding: var(--spacing-6) 0;
}

.tab-panel.active {
  display: block;
  animation: fadeIn 0.4s ease-out;
}

/* --- Data Table --- */
.data-table-wrapper {
  overflow-x: auto;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.data-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  background-color: var(--color-card);
  min-width: 600px;
}

.data-table th {
  padding: 14px 20px;
  background-color: var(--color-bg);
  text-align: left;
  font-weight: 600;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
  border-bottom: 2px solid var(--color-border);
  white-space: nowrap;
}

.data-table td {
  padding: 16px 20px;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text);
  font-size: 0.95rem;
}

.data-table tr:last-child td {
  border-bottom: none;
}

.data-table tbody tr {
  transition: background-color var(--transition-fast);
}

.data-table tbody tr:hover {
  background-color: rgba(var(--color-primary-rgb), 0.02);
}

/* --- Tags --- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.tag-primary {
  background-color: rgba(var(--color-primary-rgb), 0.1);
  color: var(--color-primary);
}

.tag-secondary {
  background-color: rgba(var(--color-secondary-rgb), 0.1);
  color: var(--color-secondary-dark);
}

.tag-easy {
  background-color: rgba(16,185,129,0.15);
  color: #34D399;
}

.tag-intermediate {
  background-color: rgba(245,158,11,0.15);
  color: #FBBF24;
}

.tag-advanced {
  background-color: rgba(239,68,68,0.15);
  color: #F87171;
}

/* ==========================================================================
   11. Progress Bar & Timeline
   ========================================================================== */

/* --- Progress Bar --- */
.progress-container {
  width: 100%;
  margin-bottom: var(--spacing-4);
}

.progress-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-2);
  font-size: 0.9rem;
  font-weight: 500;
}

.progress-bar {
  height: 8px;
  background-color: var(--color-border);
  border-radius: var(--radius-full);
  overflow: hidden;
  position: relative;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-full);
  transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.progress-fill::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(90deg, rgba(255,255,255,0) 0%, rgba(255,255,255,0.3) 50%, rgba(255,255,255,0) 100%);
  animation: shimmer 2s infinite;
}

/* --- Timeline --- */
.timeline {
  position: relative;
  padding-left: 32px;
  margin-top: var(--spacing-6);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 11px;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--color-border);
  border-radius: var(--radius-full);
}

.timeline-item {
  position: relative;
  padding-bottom: var(--spacing-8);
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: -32px;
  top: 4px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background-color: var(--color-primary);
  border: 4px solid var(--color-surface);
  z-index: 1;
  box-shadow: 0 0 0 2px rgba(var(--color-primary-rgb), 0.2);
  transition: transform var(--transition-fast);
}

.timeline-item:hover .timeline-dot {
  transform: scale(1.2);
}

.timeline-content {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  padding: var(--spacing-5);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.timeline-date {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  font-weight: 500;
  margin-bottom: var(--spacing-2);
  display: block;
}

.timeline-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: var(--spacing-2);
}

/* ==========================================================================
   12. Image Gallery, Modal, Search
   ========================================================================== */

/* --- Image Gallery --- */
.image-gallery {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-3);
  margin-bottom: var(--spacing-6);
}

.gallery-main {
  width: 100%;
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
  aspect-ratio: 16/9;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  cursor: zoom-in;
}

.gallery-main img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.gallery-main:hover img {
  transform: scale(1.03);
}

.gallery-thumbs {
  display: flex;
  gap: var(--spacing-2);
  overflow-x: auto;
  padding-bottom: 4px;
  scrollbar-width: thin;
}

.gallery-thumb {
  width: 80px;
  height: 60px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  cursor: pointer;
  opacity: 0.6;
  transition: all var(--transition-fast);
  border: 2px solid transparent;
  flex-shrink: 0;
}

.gallery-thumb:hover {
  opacity: 0.8;
}

.gallery-thumb.active {
  opacity: 1;
  border-color: var(--color-primary);
}

.gallery-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* --- Image Modal --- */
.image-modal {
  position: fixed;
  inset: 0;
  z-index: var(--z-toast);
  background-color: rgba(0,0,0,0.9);
  backdrop-filter: blur(5px);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-normal);
}

.image-modal.active {
  opacity: 1;
  pointer-events: auto;
}

.image-modal img {
  max-width: 90vw;
  max-height: 90vh;
  object-fit: contain;
  border-radius: var(--radius-md);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
  transform: scale(0.9);
  transition: transform var(--transition-normal) cubic-bezier(0.34, 1.56, 0.64, 1);
}

.image-modal.active img {
  transform: scale(1);
}

.image-modal-close {
  position: absolute;
  top: var(--spacing-5);
  right: var(--spacing-5);
  color: white;
  background-color: rgba(255,255,255,0.1);
  border-radius: 50%;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background-color var(--transition-fast);
  border: 1px solid rgba(255,255,255,0.2);
}

.image-modal-close:hover {
  background-color: rgba(255,255,255,0.2);
  transform: rotate(90deg);
}

/* --- Search Modal --- */
.search-modal {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding-top: 15vh;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-fast);
}

.search-modal.active {
  opacity: 1;
  pointer-events: auto;
}

.search-modal-overlay {
  position: absolute;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(8px);
}

.search-modal-content {
  position: relative;
  width: 100%;
  max-width: 640px;
  background-color: #0D0D0D;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl), 0 0 0 1px rgba(59,130,246,0.3), 0 0 40px rgba(59,130,246,0.12);
  overflow: hidden;
  margin: 0 var(--spacing-4);
  border: 1px solid rgba(59,130,246,0.25);
  transform: scale(0.95) translateY(-20px);
  transition: transform var(--transition-normal) cubic-bezier(0.34, 1.56, 0.64, 1);
}

.search-modal.active .search-modal-content {
  transform: scale(1) translateY(0);
}

.search-input-wrapper {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  padding: var(--spacing-4) var(--spacing-5);
  border-bottom: 1px solid var(--color-border);
  background-color: var(--color-surface);
}

.search-input-wrapper svg {
  width: 24px;
  height: 24px;
  color: var(--color-primary);
  flex-shrink: 0;
}

#search-input {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  font-size: 1.25rem;
  color: var(--color-text);
  font-family: var(--font-body);
}

#search-input::placeholder {
  color: var(--color-text-muted);
}

.search-input-wrapper kbd {
  padding: 2px 8px;
  background-color: var(--color-bg);
  border-radius: 4px;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  font-family: monospace;
}

.search-results {
  max-height: 400px;
  overflow-y: auto;
  padding: var(--spacing-2);
}

.search-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
  padding: var(--spacing-3) var(--spacing-4);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  color: inherit;
}

.search-item:hover,
.search-item.focused {
  background-color: rgba(var(--color-primary-rgb), 0.05);
}

.search-item-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background-color: var(--color-bg);
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  transition: background-color var(--transition-fast);
}

.search-item:hover .search-item-icon,
.search-item.focused .search-item-icon {
  background-color: rgba(var(--color-primary-rgb), 0.1);
  color: var(--color-primary);
}

.search-item-text {
  flex: 1;
}

.search-item-name {
  font-weight: 600;
  font-size: 1rem;
  color: var(--color-text);
  margin-bottom: 2px;
}

.search-item-type {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  text-transform: capitalize;
}

.search-empty {
  text-align: center;
  padding: var(--spacing-10) var(--spacing-5);
  color: var(--color-text-muted);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-3);
}

.search-empty svg {
  width: 48px;
  height: 48px;
  opacity: 0.5;
}

/* ==========================================================================
   13. Specific Detail Cards & Elements
   ========================================================================== */


/* --- Skeleton Loader --- */
.skeleton {
  background-color: #0E0E0E;
  border-radius: var(--radius-md);
  position: relative;
  overflow: hidden;
}

.skeleton::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.05), transparent);
  animation: shimmer 1.5s infinite;
}

.skeleton-text {
  height: 16px;
  margin-bottom: 12px;
  border-radius: 4px;
  width: 100%;
}

.skeleton-text.short { width: 60%; }
.skeleton-text.medium { width: 80%; }
.skeleton-title { height: 28px; width: 40%; margin-bottom: 16px; border-radius: 6px; }
.skeleton-image { width: 100%; aspect-ratio: 16/9; border-radius: var(--radius-lg); }
.skeleton-card { height: 200px; border-radius: var(--radius-lg); }

/* --- Scroll to Top --- */
.scroll-top {
  position: fixed;
  bottom: var(--spacing-6);
  right: var(--spacing-6);
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background-color: var(--color-primary);
  color: white;
  border: none;
  cursor: pointer;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateY(20px);
  transition: all var(--transition-normal);
  z-index: calc(var(--z-fixed) - 1);
  display: flex;
  align-items: center;
  justify-content: center;
}

.scroll-top:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-5px) !important; /* Override standard visible transform slightly */
}

.scroll-top.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Install Banner --- */
.install-banner {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: var(--color-surface);
  padding: var(--spacing-4) var(--spacing-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-4);
  box-shadow: 0 -4px 15px rgba(0,0,0,0.1);
  z-index: var(--z-fixed);
  border-top: 1px solid var(--color-border);
  transform: translateY(100%);
  transition: transform var(--transition-slow) cubic-bezier(0.16, 1, 0.3, 1);
}

.install-banner.active {
  transform: translateY(0);
}

.install-content {
  display: flex;
  align-items: center;
  gap: var(--spacing-3);
}

.install-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background-color: var(--color-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
}

.install-text h4 {
  margin: 0;
  font-size: 1rem;
}
.install-text p {
  margin: 0;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.install-actions {
  display: flex;
  gap: var(--spacing-2);
}

/* ==========================================================================
   14. Content Cards (Muscle, Exercise, Fact, etc.)
   ========================================================================== */

/* --- Page Header --- */
.page-header {
  margin-bottom: var(--spacing-8);
  padding-bottom: var(--spacing-6);
  border-bottom: 1px solid var(--color-border);
  position: relative;
}

.page-header-title {
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 800;
  margin-bottom: var(--spacing-2);
  color: var(--color-text);
  line-height: 1.1;
}

.page-header-meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-4);
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  flex-wrap: wrap;
}

.header-actions {
  position: absolute;
  top: 0;
  right: 0;
  display: flex;
  gap: var(--spacing-2);
}

/* --- Muscle Detail Card --- */
.muscle-card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  padding: var(--spacing-6);
  margin-bottom: var(--spacing-4);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-fast);
}

.muscle-card:hover {
  box-shadow: var(--shadow-md);
}

.muscle-card-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-4);
  margin-bottom: var(--spacing-4);
}

.muscle-icon {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background-color: rgba(var(--color-primary-rgb), 0.1);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.muscle-card-name {
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0;
}

.muscle-card-scientific {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  font-style: italic;
}

/* --- Exercise Card --- */
.exercise-card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  padding: var(--spacing-5);
  display: flex;
  gap: var(--spacing-4);
  margin-bottom: var(--spacing-4);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  cursor: pointer;
}

.exercise-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.exercise-thumb {
  width: 100px;
  height: 100px;
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  object-fit: cover;
  flex-shrink: 0;
}

.exercise-card-info {
  flex: 1;
}

.exercise-card-name {
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: var(--spacing-2);
  color: var(--color-text);
}

.exercise-card-muscles {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-3);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.exercise-card-meta {
  display: flex;
  gap: var(--spacing-3);
  flex-wrap: wrap;
}

.exercise-activation {
  margin-top: var(--spacing-3);
}

.exercise-activation-label {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 600;
}

/* --- Stretch Card --- */
.stretch-card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  padding: var(--spacing-5);
  margin-bottom: var(--spacing-4);
  border-left: 4px solid var(--color-secondary);
}

/* --- Injury Card --- */
.injury-card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  padding: var(--spacing-5);
  margin-bottom: var(--spacing-4);
  border-left: 4px solid var(--color-danger);
}
.injury-card.mild { border-left-color: var(--color-warning); }
.injury-card.severe { border-left-color: var(--color-danger); }

/* --- Fact Card --- */
.fact-card {
  background: linear-gradient(135deg, rgba(var(--color-primary-rgb), 0.05), rgba(var(--color-secondary-rgb), 0.05));
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-md);
  padding: var(--spacing-5);
  margin-bottom: var(--spacing-4);
  font-size: 0.95rem;
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-3);
}

.fact-card-icon {
  color: var(--color-primary);
  font-size: 1.2rem;
  margin-top: 2px;
}

/* --- Summary Box --- */
.summary-box {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  padding: var(--spacing-6);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-5);
  margin-bottom: var(--spacing-6);
}

.summary-item {
  display: flex;
  flex-direction: column;
}

.summary-item-label {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  margin-bottom: var(--spacing-1);
  font-weight: 600;
}

.summary-item-value {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
}

/* --- Function Card --- */
.function-card {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-4);
  padding: var(--spacing-4);
  background-color: var(--color-card);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  margin-bottom: var(--spacing-3);
  transition: transform var(--transition-fast);
}

.function-card:hover {
  transform: translateX(5px);
  border-color: var(--color-primary);
}

.function-icon {
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  border-radius: var(--radius-md);
  background-color: rgba(var(--color-primary-rgb), 0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  color: var(--color-primary);
}

.function-action {
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--color-text);
}

.function-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.4;
}

/* --- Everyday Use List --- */
.everyday-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: var(--spacing-3);
}

.everyday-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background-color: var(--color-card);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  font-size: 0.95rem;
  font-weight: 500;
  box-shadow: var(--shadow-sm);
}

.everyday-icon {
  font-size: 1.2rem;
}

/* --- Overview Box --- */
.overview-box {
  margin-bottom: var(--spacing-8);
}
.overview-text {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--color-text-secondary);
}

/* --- Anatomy Info Grid --- */
.anatomy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--spacing-4);
}

.anatomy-item {
  padding: var(--spacing-4);
  background-color: var(--color-card);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.anatomy-label {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  margin-bottom: 4px;
  font-weight: 600;
}

.anatomy-value {
  font-weight: 600;
  color: var(--color-text);
  font-size: 1.05rem;
}

/* --- Completed Lesson Marker --- */
.lesson-check {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  padding: 8px 12px;
  border-radius: var(--radius-md);
  background-color: rgba(var(--color-success-rgb), 0.1);
  color: var(--color-success);
  font-weight: 600;
  font-size: 0.9rem;
  border: 1px solid rgba(var(--color-success-rgb), 0.2);
  transition: all var(--transition-fast);
}

.lesson-check:hover {
  background-color: rgba(var(--color-success-rgb), 0.15);
}

.lesson-check input[type=checkbox] {
  accent-color: var(--color-success);
  width: 18px;
  height: 18px;
  cursor: pointer;
}

/* ==========================================================================
   15. Animations (Keyframes)
   ========================================================================== */

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideInLeft {
  from { opacity: 0; transform: translateX(-20px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes shimmer {
  from { transform: translateX(-100%); }
  to { transform: translateX(100%); }
}

@keyframes scaleIn {
  from { opacity: 0; transform: scale(0.95); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes heartBeat {
  0% { transform: scale(1); }
  25% { transform: scale(1.3); }
  50% { transform: scale(1); }
  75% { transform: scale(1.2); }
  100% { transform: scale(1); }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

/* Animation Utility Classes */
.fade-in { animation: fadeIn 0.4s ease forwards; }
.slide-up { animation: slideUp 0.5s ease forwards; }
.slide-down { animation: slideDown 0.5s ease forwards; }
.scale-in { animation: scaleIn 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards; }
.pulse-anim { animation: pulse 2s infinite; }

/* Staggered delays for lists/grids */
.stagger-1 { animation-delay: 0.1s; }
.stagger-2 { animation-delay: 0.2s; }
.stagger-3 { animation-delay: 0.3s; }
.stagger-4 { animation-delay: 0.4s; }
.stagger-5 { animation-delay: 0.5s; }

/* ==========================================================================
   16. Utilities
   ========================================================================== */

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-1 { margin-top: var(--spacing-2); }
.mt-2 { margin-top: var(--spacing-4); }
.mt-3 { margin-top: var(--spacing-6); }
.mt-4 { margin-top: var(--spacing-8); }
.mt-5 { margin-top: var(--spacing-10); }
.mt-6 { margin-top: var(--spacing-12); }

.mb-1 { margin-bottom: var(--spacing-2); }
.mb-2 { margin-bottom: var(--spacing-4); }
.mb-3 { margin-bottom: var(--spacing-6); }
.mb-4 { margin-bottom: var(--spacing-8); }
.mb-5 { margin-bottom: var(--spacing-10); }
.mb-6 { margin-bottom: var(--spacing-12); }

.flex { display: flex; }
.flex-col { display: flex; flex-direction: column; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-between { display: flex; align-items: center; justify-content: space-between; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }

.gap-1 { gap: var(--spacing-2); }
.gap-2 { gap: var(--spacing-4); }
.gap-3 { gap: var(--spacing-6); }
.gap-4 { gap: var(--spacing-8); }

.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--spacing-4); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--spacing-4); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--spacing-4); }

.w-full { width: 100%; }
.h-full { height: 100%; }
.relative { position: relative; }
.absolute { position: absolute; }
.overflow-hidden { overflow: hidden; }
.rounded { border-radius: var(--radius-md); }
.rounded-full { border-radius: var(--radius-full); }
.shadow { box-shadow: var(--shadow-md); }

/* ==========================================================================
   17. Responsive Breakpoints
   ========================================================================== */

@media (max-width: 1200px) {
  .body-grid {
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  }
}

@media (max-width: 1024px) {
  .sidebar {
    position: fixed;
    left: -300px;
    z-index: var(--z-overlay);
    box-shadow: var(--shadow-xl);
  }
  
  .sidebar.active {
    left: 0;
  }
  
  .sidebar-close {
    display: flex;
  }
  
  .main-content {
    margin-left: 0;
  }
  
  .sidebar-toggle {
    display: flex;
  }

  .sidebar-overlay.active {
    opacity: 1;
    pointer-events: auto;
  }
  
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .hero {
    padding: var(--spacing-12) var(--spacing-4);
    border-radius: var(--radius-lg);
  }
  
  .body-grid {
    grid-template-columns: 1fr;
  }
  
  .anatomy-grid {
    grid-template-columns: 1fr;
  }
  
  .summary-box {
    grid-template-columns: 1fr;
  }
  
  .navbar-container {
    padding: 0 var(--spacing-3);
  }

  .main-content {
    padding: var(--spacing-4);
  }

  .grid-3 { grid-template-columns: 1fr; }
  .grid-2 { grid-template-columns: 1fr; }

  .exercise-card {
    flex-direction: column;
  }
  .exercise-thumb {
    width: 100%;
    height: 160px;
  }
  
  .panel {
    width: 100%;
    right: -100%;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 2.25rem;
  }
  
  .hero-actions {
    flex-direction: column;
    width: 100%;
  }
  
  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }
  
  .page-header-title {
    font-size: 1.75rem;
  }

  .header-actions {
    position: relative;
    margin-top: var(--spacing-3);
  }

  .install-banner {
    flex-direction: column;
    text-align: center;
  }
  
  .install-actions {
    width: 100%;
  }
  
  .install-actions .btn {
    flex: 1;
  }
}

/* ==========================================================================
   18. Accessibility & Print Styles
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

@media (prefers-contrast: more) {
  :root {
    --color-border: #3F3F3F; /* Higher contrast borders on black */
    --color-text-secondary: #D4D4D8;
  }

  .card, .btn-secondary, .accordion-item, .data-table-wrapper {
    border-width: 2px;
  }
}

@media print {
  *,
  *::before,
  *::after {
    background: transparent !important;
    color: #000 !important;
    box-shadow: none !important;
    text-shadow: none !important;
  }

  body {
    background: #fff;
    font-size: 12pt;
  }

  a, a:visited {
    text-decoration: underline;
  }

  a[href]::after {
    content: " (" attr(href) ")";
  }

  abbr[title]::after {
    content: " (" attr(title) ")";
  }

  a[href^="#"]::after,
  a[href^="javascript:"]::after {
    content: "";
  }

  pre, blockquote {
    border: 1px solid #999;
    page-break-inside: avoid;
  }

  thead {
    display: table-header-group;
  }

  tr, img {
    page-break-inside: avoid;
  }

  img {
    max-width: 100% !important;
  }

  p, h2, h3 {
    orphans: 3;
    widows: 3;
  }

  h2, h3 {
    page-break-after: avoid;
  }
  
  .navbar, .sidebar, .scroll-top, .install-banner, .panel, .search-modal {
    display: none !important;
  }
  
  .main-content {
    margin: 0 !important;
    padding: 0 !important;
  }
}