/* ========================================
   GAMES DESIGN SYSTEM
   Based on IBM Carbon G100 (Dark)
   Mobile-first · Touch-optimized · 320px base
   ======================================== */

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
  scroll-behavior: smooth;
}

body {
  font-family: 'IBM Plex Sans', 'Helvetica Neue', Arial, sans-serif;
  background: var(--cds-background);
  color: var(--cds-text-primary);
  line-height: 1.5;
  min-height: 100dvh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* --- IBM Carbon G100 Tokens --- */
:root {
  /* Background & Layers */
  --cds-background: #161616;
  --cds-layer: #262626;
  --cds-layer-hover: #333333;
  --cds-layer-01: #393939;
  --cds-layer-02: #525252;
  --cds-field: #262626;
  --cds-field-hover: #333333;

  /* Text */
  --cds-text-primary: #f4f4f4;
  --cds-text-secondary: #c6c6c6;
  --cds-text-placeholder: #6f6f6f;
  --cds-text-on-color: #ffffff;
  --cds-text-inverse: #161616;

  /* Interactive */
  --cds-interactive: #0f62fe;
  --cds-interactive-hover: #0353e9;
  --cds-interactive-active: #002d9c;

  /* Borders */
  --cds-border-subtle: #393939;
  --cds-border-strong: #6f6f6f;

  /* Status */
  --cds-danger: #da1e28;
  --cds-success: #24a148;
  --cds-warning: #f1c21b;

  /* Focus */
  --cds-focus: #ffffff;

  /* Skeleton */
  --cds-skeleton-background: #353535;
  --cds-skeleton-element: #525252;

  /* Overlay */
  --cds-overlay: rgba(0, 0, 0, 0.65);

  /* Category Accent Colors */
  --cat-arcade: #0f62fe;
  --cat-puzzle: #009d9a;
  --cat-brain: #8a3ffc;
  --cat-creative: #ee5396;
  --cat-physics: #1192e8;
  --cat-sports: #1192e8;
  --cat-strategy: #198038;
  --cat-relaxation: #007d79;
  --cat-wellness: #007d79;
  --cat-survival: #da1e28;
  --cat-idle: #6f6f6f;
  --cat-sandbox: #6f6f6f;
  --cat-simulation: #0072c3;
  --cat-rhythm: #a56eff;

  /* --- Legacy aliases (for gradual migration) --- */
  --bg-primary: var(--cds-background);
  --bg-secondary: var(--cds-layer);
  --bg-card: var(--cds-layer);
  --bg-card-hover: var(--cds-layer-hover);
  --bg-surface: var(--cds-layer-01);
  --bg-game: #111111;
  --text-primary: var(--cds-text-primary);
  --text-secondary: var(--cds-text-secondary);
  --text-muted: var(--cds-text-placeholder);
  --accent: var(--cds-interactive);
  --accent-hover: var(--cds-interactive-hover);
  --accent-glow: rgba(15, 98, 254, 0.25);
  --success: var(--cds-success);
  --warning: var(--cds-warning);
  --danger: var(--cds-danger);
  --border: var(--cds-border-subtle);
  --border-hover: var(--cds-border-strong);

  /* Carbon Spacing Scale */
  --space-1: 0.125rem;  /* 2px */
  --space-2: 0.25rem;   /* 4px */
  --space-3: 0.5rem;    /* 8px */
  --space-4: 0.75rem;   /* 12px */
  --space-5: 1rem;      /* 16px */
  --space-6: 1.5rem;    /* 24px */
  --space-7: 2rem;      /* 32px */
  --space-8: 2.5rem;    /* 40px */
  --space-9: 3rem;      /* 48px */
  --space-10: 4rem;     /* 64px */

  /* Carbon Typography */
  --font-xs: 0.75rem;    /* 12px */
  --font-sm: 0.875rem;   /* 14px */
  --font-base: 1rem;     /* 16px */
  --font-lg: 1.25rem;    /* 20px */
  --font-xl: 1.5rem;     /* 24px */
  --font-2xl: 1.75rem;   /* 28px */
  --font-3xl: 2rem;      /* 32px */
  --font-4xl: 2.625rem;  /* 42px */

  --weight-light: 300;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-semibold: 600;
  --weight-bold: 700;

  /* Carbon Radius (tighter than before) */
  --radius-xs: 2px;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-full: 9999px;

  /* Carbon Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 2px 6px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);

  /* Carbon Motion (Productive) */
  --ease-standard: cubic-bezier(0.2, 0, 0.38, 0.9);
  --ease-entrance: cubic-bezier(0, 0, 0.38, 0.9);
  --ease-exit: cubic-bezier(0.2, 0, 1, 0.9);
  /* Expressive (for modals, major transitions) */
  --ease-expressive: cubic-bezier(0.2, 0, 0, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Legacy motion aliases */
  --ease-out: var(--ease-standard);

  /* Carbon Durations */
  --duration-fast-01: 70ms;
  --duration-fast-02: 110ms;
  --duration-moderate-01: 150ms;
  --duration-moderate-02: 240ms;
  --duration-slow-01: 400ms;
  --duration-slow-02: 700ms;

  /* Legacy duration aliases */
  --duration-fast: var(--duration-moderate-01);
  --duration-normal: var(--duration-moderate-02);
  --duration-slow: var(--duration-slow-01);

  /* Touch targets (48px minimum per WCAG) */
  --touch-target: 3rem;
  --touch-target-lg: 3.5rem;

  /* Layout */
  --content-max: 1200px;
  --game-max: 500px;
  --nav-height: 3rem;
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --safe-top: env(safe-area-inset-top, 0px);
}

/* --- IBM Carbon G10 Light Theme --- */
[data-theme="light"] {
  --cds-background: #f4f4f4;
  --cds-layer: #ffffff;
  --cds-layer-hover: #e8e8e8;
  --cds-layer-01: #e0e0e0;
  --cds-layer-02: #c6c6c6;
  --cds-field: #ffffff;
  --cds-field-hover: #e8e8e8;
  --cds-text-primary: #161616;
  --cds-text-secondary: #525252;
  --cds-text-placeholder: #a8a8a8;
  --cds-text-on-color: #ffffff;
  --cds-text-inverse: #f4f4f4;
  --cds-interactive: #0f62fe;
  --cds-interactive-hover: #0353e9;
  --cds-interactive-active: #002d9c;
  --cds-border-subtle: #e0e0e0;
  --cds-border-strong: #8d8d8d;
  --cds-danger: #da1e28;
  --cds-success: #24a148;
  --cds-warning: #f1c21b;
  --cds-focus: #0f62fe;
  --cds-skeleton-background: #e0e0e0;
  --cds-skeleton-element: #c6c6c6;
  --cds-overlay: rgba(22, 22, 22, 0.5);

  /* Legacy aliases update for light */
  --bg-primary: var(--cds-background);
  --bg-secondary: var(--cds-layer);
  --bg-card: var(--cds-layer);
  --bg-card-hover: var(--cds-layer-hover);
  --bg-surface: var(--cds-layer-01);
  --bg-game: #e8e8e8;
  --text-primary: var(--cds-text-primary);
  --text-secondary: var(--cds-text-secondary);
  --text-muted: var(--cds-text-placeholder);
  --accent: var(--cds-interactive);
  --accent-hover: var(--cds-interactive-hover);
  --accent-glow: rgba(15, 98, 254, 0.15);
  --border: var(--cds-border-subtle);
  --border-hover: var(--cds-border-strong);
}

[data-theme="light"] .nav {
  background: rgba(244, 244, 244, 0.9);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

/* --- Typography --- */
h1, h2, h3, h4 {
  font-weight: var(--weight-semibold);
  line-height: 1.25;
  letter-spacing: -0.01em;
}

h1 { font-size: var(--font-3xl); }
h2 { font-size: var(--font-xl); }
h3 { font-size: var(--font-lg); }
h4 { font-size: var(--font-base); }

@media (min-width: 768px) {
  h1 { font-size: var(--font-4xl); }
  h2 { font-size: var(--font-2xl); }
  h3 { font-size: var(--font-xl); }
}

/* --- Buttons (Carbon-inspired) --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  min-height: var(--touch-target);
  padding: var(--space-4) var(--space-6);
  font-family: inherit;
  font-size: var(--font-sm);
  font-weight: var(--weight-medium);
  letter-spacing: 0.01em;
  border: none;
  border-radius: 0;
  cursor: pointer;
  transition: background var(--duration-moderate-01) var(--ease-standard),
              border-color var(--duration-moderate-01) var(--ease-standard);
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--cds-interactive);
  color: var(--cds-text-on-color);
}

.btn-primary:hover {
  background: var(--cds-interactive-hover);
}

.btn-primary:active {
  background: var(--cds-interactive-active);
}

.btn-secondary {
  background: var(--cds-layer-01);
  color: var(--cds-text-primary);
  border: 1px solid var(--cds-border-subtle);
}

.btn-secondary:hover {
  background: var(--cds-layer-02);
  border-color: var(--cds-border-strong);
}

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

.btn-ghost:hover {
  background: var(--cds-layer);
  color: var(--cds-text-primary);
}

.btn-sm {
  min-height: 2rem;
  padding: var(--space-2) var(--space-4);
  font-size: var(--font-xs);
}

.btn-lg {
  min-height: var(--touch-target-lg);
  padding: var(--space-5) var(--space-7);
  font-size: var(--font-base);
}

.btn-icon {
  width: var(--touch-target);
  padding: 0;
}

/* --- Cards (Carbon-inspired) --- */
.card {
  background: var(--cds-layer);
  border: 1px solid var(--cds-border-subtle);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: background var(--duration-moderate-01) var(--ease-standard),
              border-color var(--duration-moderate-01) var(--ease-standard),
              box-shadow var(--duration-moderate-02) var(--ease-standard);
}

.card:hover {
  background: var(--cds-layer-hover);
  border-color: var(--cds-border-strong);
  box-shadow: var(--shadow-md);
}

.card:active {
  background: var(--cds-layer-01);
}

.card-body {
  padding: var(--space-5);
}

/* --- Card Link (game cards) --- */
a {
  color: var(--cds-interactive);
}

.game-card-link {
  text-decoration: none;
  color: inherit;
  display: block;
}

.game-card-link:hover {
  color: inherit;
}

.game-card-title {
  font-weight: var(--weight-semibold);
  font-size: var(--font-sm);
  margin-bottom: 2px;
  line-height: 1.3;
  color: var(--cds-text-primary);
}

.game-card-desc {
  font-size: var(--font-xs);
  color: var(--cds-text-secondary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.4;
}

.game-card-meta {
  display: flex;
  gap: var(--space-2);
  margin-top: var(--space-3);
  flex-wrap: wrap;
}

.card-thumb {
  aspect-ratio: 16 / 10;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-4xl);
  overflow: hidden;
  position: relative;
}

/* Category-colored thumb backgrounds */
.card-thumb[data-category="arcade"]      { background: linear-gradient(135deg, rgba(15,98,254,0.12), var(--cds-layer)); }
.card-thumb[data-category="puzzle"]      { background: linear-gradient(135deg, rgba(0,157,154,0.12), var(--cds-layer)); }
.card-thumb[data-category="brain"]       { background: linear-gradient(135deg, rgba(138,63,252,0.12), var(--cds-layer)); }
.card-thumb[data-category="creative"]    { background: linear-gradient(135deg, rgba(238,83,150,0.12), var(--cds-layer)); }
.card-thumb[data-category="physics"]     { background: linear-gradient(135deg, rgba(17,146,232,0.12), var(--cds-layer)); }
.card-thumb[data-category="sports"]      { background: linear-gradient(135deg, rgba(17,146,232,0.12), var(--cds-layer)); }
.card-thumb[data-category="strategy"]    { background: linear-gradient(135deg, rgba(25,128,56,0.12), var(--cds-layer)); }
.card-thumb[data-category="relaxation"]  { background: linear-gradient(135deg, rgba(0,125,121,0.12), var(--cds-layer)); }
.card-thumb[data-category="wellness"]    { background: linear-gradient(135deg, rgba(0,125,121,0.12), var(--cds-layer)); }
.card-thumb[data-category="survival"]    { background: linear-gradient(135deg, rgba(218,30,40,0.12), var(--cds-layer)); }
.card-thumb[data-category="idle"]        { background: linear-gradient(135deg, rgba(111,111,111,0.12), var(--cds-layer)); }
.card-thumb[data-category="sandbox"]     { background: linear-gradient(135deg, rgba(111,111,111,0.12), var(--cds-layer)); }
.card-thumb[data-category="simulation"]  { background: linear-gradient(135deg, rgba(0,114,195,0.12), var(--cds-layer)); }
.card-thumb[data-category="rhythm"]      { background: linear-gradient(135deg, rgba(165,110,255,0.12), var(--cds-layer)); }

/* --- Tags / Chips (Carbon Tag) --- */
.tag {
  display: inline-flex;
  align-items: center;
  padding: 2px var(--space-3);
  font-size: var(--font-xs);
  font-weight: var(--weight-normal);
  letter-spacing: 0.01em;
  border-radius: var(--radius-full);
  background: var(--cds-layer-01);
  color: var(--cds-text-secondary);
  white-space: nowrap;
  text-decoration: none;
}

.tag:hover {
  background: var(--cds-layer-02);
  color: var(--cds-text-primary);
}

/* --- Form / Search (Carbon Field) --- */
.input {
  width: 100%;
  min-height: var(--touch-target);
  padding: var(--space-4) var(--space-5);
  font-family: inherit;
  font-size: var(--font-sm);
  color: var(--cds-text-primary);
  background: var(--cds-field);
  border: none;
  border-bottom: 1px solid var(--cds-border-strong);
  outline: none;
  transition: border-color var(--duration-fast-02) var(--ease-standard);
}

.input:focus {
  border-bottom: 2px solid var(--cds-interactive);
}

.input::placeholder {
  color: var(--cds-text-placeholder);
}

.search-wrapper {
  position: relative;
}

.search-wrapper .search-icon {
  position: absolute;
  left: var(--space-5);
  top: 50%;
  transform: translateY(-50%);
  color: var(--cds-text-placeholder);
  pointer-events: none;
}

.search-wrapper .input {
  padding-left: 2.75rem;
}

/* --- Grid --- */
.game-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-5);
}

@media (min-width: 480px) {
  .game-grid {
    gap: var(--space-5);
  }
}

@media (min-width: 768px) {
  .game-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-6);
  }
}

@media (min-width: 1024px) {
  .game-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* --- Layout --- */
.container {
  width: 100%;
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 var(--space-5);
}

@media (min-width: 768px) {
  .container {
    padding: 0 var(--space-7);
  }
}

/* --- Nav (Carbon Header) --- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  background: var(--cds-background);
  border-bottom: 1px solid var(--cds-border-subtle);
  display: flex;
  align-items: center;
}

.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: var(--font-sm);
  font-weight: var(--weight-semibold);
  color: var(--cds-text-primary);
  text-decoration: none;
  letter-spacing: 0.01em;
}

.nav-logo span {
  color: var(--cds-text-primary);
}

/* --- Game Shell --- */
.game-shell {
  display: flex;
  flex-direction: column;
  min-height: calc(100dvh - var(--nav-height));
}

.game-viewport {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-5);
  background: var(--bg-game);
}

.game-canvas-wrap {
  width: 100%;
  max-width: var(--game-max);
  aspect-ratio: 1 / 1;
  position: relative;
}

.game-canvas-wrap canvas {
  width: 100%;
  height: 100%;
  display: block;
  border-radius: var(--radius-sm);
  touch-action: none;
}

.game-controls {
  padding: var(--space-4) var(--space-5);
  padding-bottom: calc(var(--space-4) + var(--safe-bottom));
  background: var(--cds-layer);
  border-top: 1px solid var(--cds-border-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
}

.game-hud {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-3) var(--space-4);
  pointer-events: none;
}

.hud-slot {
  text-align: center;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  border-radius: var(--radius-sm);
  padding: var(--space-1) var(--space-3);
}

.hud-slot .label {
  font-size: 0.625rem;
  color: rgba(255, 255, 255, 0.6);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: var(--weight-medium);
  display: block;
  line-height: 1;
  margin-bottom: 1px;
}

.hud-slot .value {
  font-size: var(--font-base);
  font-weight: var(--weight-semibold);
  color: #ffffff;
  font-variant-numeric: tabular-nums;
}

/* --- Filter Bar --- */
.filter-bar {
  display: flex;
  gap: var(--space-3);
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
  padding: var(--space-3) 0;
  -webkit-overflow-scrolling: touch;
  mask-image: linear-gradient(to right, transparent 0, black 8px, black calc(100% - 24px), transparent 100%);
  -webkit-mask-image: linear-gradient(to right, transparent 0, black 8px, black calc(100% - 24px), transparent 100%);
}

.filter-bar::-webkit-scrollbar {
  display: none;
}

.filter-chip {
  display: inline-flex;
  align-items: center;
  padding: var(--space-2) var(--space-4);
  font-size: var(--font-xs);
  font-weight: var(--weight-medium);
  letter-spacing: 0.01em;
  border-radius: var(--radius-full);
  background: var(--cds-layer);
  color: var(--cds-text-secondary);
  border: 1px solid var(--cds-border-subtle);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--duration-fast-02) var(--ease-standard);
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
  min-height: 2rem;
}

.filter-chip:hover {
  background: var(--cds-layer-hover);
  color: var(--cds-text-primary);
}

.filter-chip.active {
  background: var(--cds-interactive);
  color: var(--cds-text-on-color);
  border-color: var(--cds-interactive);
}

/* --- Modal / Overlay --- */
.overlay {
  position: fixed;
  inset: 0;
  z-index: 200;
  background: var(--cds-overlay);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: flex-end;
  justify-content: center;
}

@media (min-width: 768px) {
  .overlay {
    align-items: center;
  }
}

.modal {
  background: var(--cds-layer);
  border-top: 1px solid var(--cds-border-subtle);
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  padding: var(--space-7) var(--space-6);
  padding-bottom: calc(var(--space-7) + var(--safe-bottom));
  width: 100%;
  max-width: 420px;
  text-align: center;
}

@media (min-width: 768px) {
  .modal {
    border: 1px solid var(--cds-border-subtle);
    border-radius: var(--radius-sm);
    padding-bottom: var(--space-7);
  }
}

/* --- Utilities --- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.text-center { text-align: center; }
.text-muted { color: var(--cds-text-secondary); }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.mt-4 { margin-top: var(--space-5); }
.mt-8 { margin-top: var(--space-7); }
.mb-4 { margin-bottom: var(--space-5); }
.mb-6 { margin-bottom: var(--space-6); }
.w-full { width: 100%; }

/* --- Animations (Carbon Motion) --- */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

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

.animate-fade { animation: fadeIn var(--duration-moderate-02) var(--ease-entrance); }
.animate-slide { animation: slideUp var(--duration-slow-01) var(--ease-entrance); }
.animate-scale { animation: scaleIn var(--duration-moderate-02) var(--ease-expressive); }

/* --- Skeleton Loading --- */
.skeleton {
  background: linear-gradient(90deg, var(--cds-skeleton-background) 25%, var(--cds-skeleton-element) 50%, var(--cds-skeleton-background) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

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