:root {
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-surface-light: #334155;
  --color-text: #f1f5f9;
  --color-text-dim: #94a3b8;
  --color-primary: #06b6d4;
  --color-accent: #0891b2;
  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  --color-info: #3b82f6;

  /* Lighter text on dark UI for WCAG AA on tinted badge backgrounds */
  --color-success-readable: #6ee7b7;
  --color-warning-readable: #fde68a;
  --color-danger-readable: #fecaca;
  --color-info-readable: #93c5fd;

  /* Z-index scale: content < header < modals < overlays/toasts */
  --z-layer-base: 1;
  --z-layer-sticky: 10;
  --z-layer-banner: 90;
  --z-layer-header: 100;
  --z-layer-modal: 1000;
  --z-layer-modal-video: 1050;
  --z-layer-modal-video-content: 1051;
  --z-layer-modal-video-close: 1052;
  --z-layer-modal-raised: 1100;
  --z-layer-overlay: 2000;

  /* Aliases used by warm-up-protocols / exercise-progressions / pre-post modals */
  --color-background: var(--color-bg);
  --color-background-secondary: var(--color-surface);
  --color-background-hover: rgba(148, 163, 184, 0.12);
  --color-primary-background: rgba(6, 182, 212, 0.15);
  --color-primary-dark: #0e7490;
  --color-success-background: rgba(16, 185, 129, 0.15);
  --color-warning-background: rgba(245, 158, 11, 0.15);
  --color-info-bg: rgba(59, 130, 246, 0.12);
  --color-success-bg: rgba(16, 185, 129, 0.12);

  /* Semantic aliases for components */
  --color-bg-primary: var(--color-bg);
  --color-bg-secondary: var(--color-surface);
  --color-bg-tertiary: var(--color-surface-light);
  --color-bg-quaternary: #475569;
  --color-text-secondary: var(--color-text-dim);
  --color-text-muted: #64748b;
  --color-border: var(--color-surface-light);
  --color-border-subtle: rgba(148, 163, 184, 0.2);

  --radius-md: 8px;
  --radius-sm: 4px;

  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;

  --tap-target-min: 44px;
  --tap-target-large: 60px;
  --tap-target-huge: 70px;

  --font-xs: 12px;
  --font-sm: 14px;
  --font-md: 16px;
  --font-lg: 18px;
  --font-xl: 24px;
  --font-xxl: 32px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  font-size: max(14px, 1rem);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Keyboard focus: visible ring (mouse clicks stay uncluttered) */
:where(
  button,
  a,
  input:not([type="hidden"]),
  select,
  textarea,
  [tabindex]:not([tabindex="-1"])
):focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

#app {
  max-width: 430px;
  margin: 0 auto;
  min-height: 100vh;
  background: var(--color-bg);
}

/* Utility Classes */
.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;
}

/* Modal Base Styles */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.9);
  z-index: var(--z-layer-modal);
  justify-content: center;
  align-items: center;
  padding: var(--spacing-md);
}

.modal-content {
  background: var(--color-bg);
  border-radius: 16px;
  padding: var(--spacing-lg);
  max-width: 500px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-md);
}

.modal-header h2 {
  margin: 0;
  font-size: var(--font-xl);
  color: var(--color-text);
}

.modal-body {
  margin-bottom: var(--spacing-md);
}

.modal-actions {
  display: flex;
  gap: var(--spacing-sm);
  margin-top: var(--spacing-lg);
}

/* Screen Management */
.screen {
  display: none;
}

.screen.active {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
}

/* Header */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md);
  background: var(--color-primary);
  position: sticky;
  top: 0;
  z-index: var(--z-layer-header);
  min-height: 60px;
  box-shadow: 0 2px 8px rgba(6, 182, 212, 0.3);
}

.app-header h1 {
  font-size: var(--font-xl);
  font-weight: 600;
}

.icon-btn {
  min-width: var(--tap-target-min);
  min-height: var(--tap-target-min);
  background: transparent;
  border: none;
  color: var(--color-text);
  font-size: var(--font-lg);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  transition: background 0.2s;
}

.icon-btn:active {
  background: rgba(255, 255, 255, 0.1);
}

/* Screen Content */
.screen-content {
  flex: 1;
  padding: var(--spacing-md);
}

/* Buttons */
.btn-primary {
  width: 100%;
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: 12px;
  padding: var(--spacing-md);
  min-height: var(--tap-target-min);
  font-size: var(--font-lg);
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.1s, box-shadow 0.2s, background 0.2s;
  box-shadow: 0 2px 8px rgba(6, 182, 212, 0.3);
}

.btn-primary:hover {
  background: var(--color-accent);
}

.btn-primary:active {
  transform: scale(0.98);
  box-shadow: 0 1px 4px rgba(6, 182, 212, 0.3);
}

.btn-large {
  min-height: var(--tap-target-large);
  padding: var(--spacing-md);
}

/* Cards */
.workout-card,
.recovery-card,
.quick-actions {
  background: var(--color-surface);
  border-radius: 12px;
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
}

.workout-card h2,
.recovery-card h3,
.quick-actions h3 {
  font-size: var(--font-lg);
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

.workout-name {
  font-size: var(--font-xxl);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  color: var(--color-primary);
}

.meta {
  font-size: var(--font-sm);
  color: var(--color-text-dim);
  margin-bottom: var(--spacing-lg);
}

/* Quick Actions */
.action-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--spacing-md);
}

.action-btn {
  min-height: var(--tap-target-large);
  background: var(--color-surface-light);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 12px;
  color: var(--color-text);
  font-size: var(--font-md);
  cursor: pointer;
  transition: background 0.2s;
}

.action-btn:active {
  background: var(--color-surface);
}

/* Recovery Status */
.recovery-ok {
  color: var(--color-success);
  font-size: var(--font-md);
}

.recovery-warning {
  color: var(--color-warning);
  font-size: var(--font-md);
}

/* Mobility Check Modal */
.mobility-check-modal h2 {
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

.mobility-question {
  font-size: var(--font-lg);
  margin: var(--spacing-md) 0;
  font-weight: 500;
  color: var(--color-text);
}

.mobility-help {
  background: rgba(6, 182, 212, 0.1);
  padding: var(--spacing-md);
  border-radius: 8px;
  font-size: var(--font-sm);
  color: var(--color-primary);
  margin: var(--spacing-md) 0;
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  border-left: 4px solid var(--color-primary);
}

.mobility-help .help-icon {
  flex-shrink: 0;
  font-size: var(--font-md);
}

.mobility-help-text {
  flex: 1;
}

.mobility-buttons {
  display: flex;
  gap: var(--spacing-sm);
  margin: var(--spacing-lg) 0 var(--spacing-md) 0;
}

.mobility-buttons button {
  flex: 1;
  padding: var(--spacing-md);
  font-size: var(--font-md);
  border-radius: 8px;
  cursor: pointer;
  border: none;
  font-weight: 600;
  transition: transform 0.1s, opacity 0.2s;
  min-height: var(--tap-target-min);
}

.mobility-buttons button:active {
  transform: scale(0.98);
}

.btn-success {
  background: var(--color-success);
  color: white;
}

.btn-success:hover {
  opacity: 0.9;
}

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

.btn-danger:hover {
  opacity: 0.9;
}

.mobility-progress,
.mobility-recent {
  font-size: var(--font-sm);
  color: var(--color-text-dim);
  margin: var(--spacing-xs) 0;
}

.mobility-progress {
  font-weight: 500;
}

.mobility-recent {
  font-family: monospace;
  letter-spacing: 0.2em;
}

/* Pain Tracking Modal */
.pain-question {
  font-size: 1.1rem;
  margin: 1rem 0;
  text-align: center;
}

.pain-severity-buttons {
  display: flex;
  gap: 0.5rem;
  margin: 1rem 0;
}

.pain-severity-buttons button {
  flex: 1;
}

.pain-location-label {
  font-weight: bold;
  margin-top: 1rem;
  margin-bottom: 0.5rem;
}

.pain-location-buttons {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 0.5rem;
  margin: 1rem 0;
}

.pain-history {
  font-size: 0.9rem;
  margin-top: 1rem;
  padding: 0.5rem;
  background: #f5f5f5;
  border-radius: 4px;
  text-align: center;
}

/* Progress Dashboard */
.progress-dashboard {
  padding: var(--spacing-md) 0;
}

.dashboard-title {
  text-align: center;
  margin-bottom: var(--spacing-lg);
  font-size: var(--font-lg);
  color: var(--color-text);
}

.progression-card {
  background: var(--color-surface);
  border-radius: 12px;
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.progression-title {
  text-align: center;
  font-size: var(--font-lg);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
  font-weight: 500;
}

.progression-percentage {
  text-align: center;
  font-size: var(--font-xl);
  font-weight: bold;
  margin-bottom: var(--spacing-sm);
  color: var(--color-primary);
}

.progress-bar-container {
  height: 24px;
  background: var(--color-surface-light);
  border-radius: 12px;
  overflow: hidden;
  margin-bottom: var(--spacing-md);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #10b981, #34d399);
  transition: width 0.3s ease;
  box-shadow: 0 0 8px rgba(16, 185, 129, 0.4);
}

.criteria-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}

.criterion {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm);
  border-radius: 8px;
  background: var(--color-surface-light);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.criterion-met {
  background: rgba(16, 185, 129, 0.15);
  border-color: rgba(16, 185, 129, 0.3);
}

.criterion-progress {
  background: rgba(245, 158, 11, 0.15);
  border-color: rgba(245, 158, 11, 0.3);
}

.criterion-not-started {
  background: rgba(239, 68, 68, 0.15);
  border-color: rgba(239, 68, 68, 0.3);
}

.criterion-icon {
  font-size: var(--font-lg);
  flex-shrink: 0;
}

.criterion-text {
  flex: 1;
  font-size: var(--font-md);
  color: var(--color-text);
}

.next-step {
  text-align: center;
  padding: var(--spacing-md);
  background: rgba(6, 182, 212, 0.15);
  border-radius: 8px;
  font-weight: 500;
  color: var(--color-primary);
  font-size: var(--font-md);
  border: 1px solid rgba(6, 182, 212, 0.3);
}

/* Mobile optimizations */
@media (max-width: 400px) {
  .screen-content {
    padding: var(--spacing-sm);
  }

  .workout-card,
  .recovery-card,
  .quick-actions {
    padding: var(--spacing-md);
  }

  .mobility-buttons {
    flex-direction: column;
  }

  .mobility-buttons button {
    width: 100%;
  }

  .action-grid {
    grid-template-columns: 1fr;
  }

  .progression-card {
    padding: var(--spacing-md);
  }

  .dashboard-title {
    font-size: var(--font-md);
  }
}

/**
 * Exercise Library Screen
 */

/* Exercise Library uses .screen-content for padding */

.library-controls {
  margin-bottom: var(--spacing-lg);
}

.library-search {
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-md);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text);
  margin-bottom: var(--spacing-md);
}

.library-search::placeholder {
  color: var(--color-text-secondary);
}

.filter-pills {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.filter-pill {
  padding: 6px 16px;
  min-height: var(--tap-target-min);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  color: var(--color-text);
  font-size: var(--font-sm);
  cursor: pointer;
  transition: all 0.2s;
  box-sizing: border-box;
}

.filter-pill:hover {
  background: var(--color-bg-tertiary);
  border-color: var(--color-primary);
}

.filter-pill.active {
  background: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

.library-exercise-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--spacing-md);
}

.library-exercise-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  cursor: pointer;
  transition: all 0.2s;
}

.library-exercise-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  border-color: var(--color-primary);
}

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

.library-card-icon {
  font-size: 24px;
}

.library-card-title {
  margin: 0;
  font-size: var(--font-md);
  color: var(--color-text);
}

.library-card-metadata {
  display: flex;
  gap: var(--spacing-xs);
  margin-bottom: var(--spacing-md);
  flex-wrap: wrap;
}

.badge-category {
  font-weight: 600;
}

.badge-warmup {
  background: rgba(251, 146, 60, 0.15);
  color: #fb923c;
  border: 1px solid rgba(251, 146, 60, 0.3);
}

.badge-exercise {
  background: rgba(59, 130, 246, 0.15);
  color: #3b82f6;
  border: 1px solid rgba(59, 130, 246, 0.3);
}

.library-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.library-card-duration {
  font-size: var(--font-sm);
  color: var(--color-text-secondary);
}

.library-card-watch-btn {
  padding: 6px 12px;
  min-height: var(--tap-target-min);
  min-width: var(--tap-target-min);
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--font-sm);
  cursor: pointer;
  transition: background 0.2s;
  box-sizing: border-box;
}

.library-card-watch-btn:hover {
  background: var(--color-accent);
}

.library-empty {
  text-align: center;
  padding: var(--spacing-xl);
  color: var(--color-text-secondary);
}

.library-empty-hint {
  font-size: var(--font-sm);
  margin-top: var(--spacing-xs);
}

/* Watch Demo button (in workout) */
.watch-demo-btn {
  padding: 8px 12px;
  min-height: var(--tap-target-min);
  background: var(--color-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--font-sm);
  cursor: pointer;
  transition: background 0.2s;
  flex: 1 1 calc(50% - var(--spacing-sm) / 2);
  min-width: 140px;
  box-sizing: border-box;
}

.watch-demo-btn:hover {
  background: var(--color-accent);
}

/* Warmup video icon */
.warmup-video-icon {
  margin-left: var(--spacing-sm);
  padding: 4px 8px;
  min-width: var(--tap-target-min);
  min-height: var(--tap-target-min);
  background: transparent;
  border: none;
  font-size: 18px;
  cursor: pointer;
  opacity: 0.7;
  transition: opacity 0.2s;
  box-sizing: border-box;
}

.warmup-video-icon:hover {
  opacity: 1;
}

/* Mobile responsive */
@media (max-width: 768px) {
  .library-exercise-list {
    grid-template-columns: 1fr;
  }
}