/* =============================================================
   shared/css/base.css
   Global CSS custom properties, reset, typography, and layout
   utilities shared across all games in kids-math-tools.
   ============================================================= */

/* ── Custom Properties ──────────────────────────────────────── */
:root {
  /* Brand palette */
  --color-bg:            #e8f4fd;
  --color-surface:       #ffffff;
  --color-surface-alt:   #f0f8ff;

  /* Answer button colours (cycled by index) */
  --color-btn-a:         #ff6b6b;  /* coral   */
  --color-btn-b:         #4ecdc4;  /* teal    */
  --color-btn-c:         #ffe66d;  /* yellow  */

  /* Semantic colours */
  --color-primary:       #5c7cfa;  /* blue-purple */
  --color-success:       #51cf66;  /* green  */
  --color-danger:        #ff6b6b;  /* red    */
  --color-warning:       #fcc419;  /* amber  */
  --color-text:          #2d3436;
  --color-text-light:    #636e72;

  /* Timer ring colours */
  --timer-color-safe:    #51cf66;
  --timer-color-warn:    #fcc419;
  --timer-color-alert:   #ff922b;
  --timer-color-danger:  #ff6b6b;

  /* Typography */
  --font-family:         'Nunito', system-ui, sans-serif;
  --font-size-xs:        0.85rem;
  --font-size-sm:        1rem;
  --font-size-md:        1.25rem;
  --font-size-lg:        1.75rem;
  --font-size-xl:        2.5rem;
  --font-size-xxl:       3.5rem;
  --font-weight-regular: 600;
  --font-weight-bold:    800;

  /* Spacing */
  --space-xs:  0.35rem;
  --space-sm:  0.75rem;
  --space-md:  1.25rem;
  --space-lg:  2rem;
  --space-xl:  3rem;

  /* Radii */
  --radius-sm:   0.75rem;
  --radius-md:   1.25rem;
  --radius-lg:   2rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.10);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.14);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.18);

  /* Transitions */
  --transition-fast:   0.15s ease;
  --transition-normal: 0.25s ease;
  --transition-slow:   0.4s ease;

  /* Touch target minimum (Apple HIG) */
  --touch-min: 56px;

  /* Layout */
  --content-max-width: 860px;
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  touch-action: manipulation;   /* disables 300ms tap delay on mobile */
}

body {
  font-family:      var(--font-family);
  font-weight:      var(--font-weight-regular);
  background-color: var(--color-bg);
  color:            var(--color-text);
  min-height:       100dvh;
  overflow-x:       hidden;
  -webkit-font-smoothing: antialiased;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

/* ── Layout Utilities ────────────────────────────────────────── */
.kmg-container {
  width: 100%;
  max-width: var(--content-max-width);
  margin-inline: auto;
  padding-inline: var(--space-md);
}

.kmg-center {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.kmg-screen {
  min-height: 100dvh;
  padding: var(--space-lg) var(--space-md);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
}

/* ── Card ────────────────────────────────────────────────────── */
.kmg-card {
  background:    var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow:    var(--shadow-md);
  padding:       var(--space-lg);
}

/* ── Buttons ─────────────────────────────────────────────────── */
.kmg-btn {
  display:         inline-flex;
  align-items:     center;
  justify-content: center;
  min-height:      var(--touch-min);
  padding:         var(--space-sm) var(--space-lg);
  border-radius:   var(--radius-full);
  font-size:       var(--font-size-md);
  font-weight:     var(--font-weight-bold);
  color:           var(--color-text);
  box-shadow:      var(--shadow-sm);
  transition:      transform var(--transition-fast),
                   box-shadow var(--transition-fast),
                   opacity var(--transition-fast);
}

.kmg-btn:active {
  transform:   scale(0.95);
  box-shadow:  none;
}

.kmg-btn--primary {
  background: var(--color-primary);
  color:      #ffffff;
  font-size:  var(--font-size-lg);
  min-width:  240px;
  box-shadow: var(--shadow-md);
}

.kmg-btn--primary:active {
  background: #4263eb;
}

/* ── Screen visibility ───────────────────────────────────────── */
.kmg-hidden {
  display: none !important;
}

/* ── Animations ──────────────────────────────────────────────── */
@keyframes kmg-pulse {
  0%, 100% { transform: scale(1);    }
  50%       { transform: scale(1.08); }
}

@keyframes kmg-blink {
  0%, 49% { opacity: 1; }
  50%, 100% { opacity: 0.2; }
}

@keyframes kmg-pop-in {
  0%   { transform: scale(0.7); opacity: 0; }
  70%  { transform: scale(1.06); }
  100% { transform: scale(1);   opacity: 1; }
}

@keyframes kmg-shake {
  0%, 100% { transform: translateX(0); }
  20%       { transform: translateX(-8px); }
  40%       { transform: translateX(8px); }
  60%       { transform: translateX(-5px); }
  80%       { transform: translateX(5px); }
}

@keyframes kmg-flash-correct {
  0%   { background: var(--color-success); transform: scale(1.04); }
  100% { background: var(--color-success); }
}

@keyframes kmg-flash-wrong {
  0%   { background: var(--color-danger); }
  100% { background: var(--color-danger); }
}

/* ── Hub / Game Card Grid ────────────────────────────────────── */
.kmg-hub {
  background: linear-gradient(160deg, #a8d8ea 0%, #e8f4fd 60%, #ffcbcb 100%);
}

.kmg-hub__title {
  font-size:   var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  text-align:  center;
  color:       var(--color-primary);
  text-shadow: 0 2px 8px rgba(92, 124, 250, 0.18);
}

.kmg-hub__subtitle {
  font-size:  var(--font-size-md);
  color:      var(--color-text-light);
  text-align: center;
}

.kmg-game-grid {
  display:               grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap:                   var(--space-lg);
  width:                 100%;
}

.kmg-game-card {
  background:     var(--color-surface);
  border-radius:  var(--radius-lg);
  box-shadow:     var(--shadow-md);
  padding:        var(--space-lg);
  display:        flex;
  flex-direction: column;
  align-items:    center;
  gap:            var(--space-md);
  text-decoration: none;
  color:          inherit;
  transition:     transform var(--transition-normal),
                  box-shadow var(--transition-normal);
}

.kmg-game-card:hover,
.kmg-game-card:focus-visible {
  transform:  translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.kmg-game-card:active {
  transform: scale(0.97);
}

.kmg-game-card__icon {
  font-size: 4rem;
  line-height: 1;
}

.kmg-game-card__title {
  font-size:   var(--font-size-lg);
  font-weight: var(--font-weight-bold);
  text-align:  center;
}

.kmg-game-card__desc {
  font-size:  var(--font-size-sm);
  color:      var(--color-text-light);
  text-align: center;
}

.kmg-game-card__badge {
  background:    var(--color-primary);
  color:         #fff;
  border-radius: var(--radius-full);
  padding:       var(--space-xs) var(--space-sm);
  font-size:     var(--font-size-xs);
  font-weight:   var(--font-weight-bold);
}

/* ── Range / Slider ──────────────────────────────────────────── */
.kmg-slider {
  -webkit-appearance: none;
  appearance:         none;
  width:              100%;
  height:             12px;
  border-radius:      var(--radius-full);
  background:         #d0e8ff;
  outline:            none;
  cursor:             pointer;
}

.kmg-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance:         none;
  width:              44px;
  height:             44px;
  border-radius:      50%;
  background:         var(--color-primary);
  box-shadow:         var(--shadow-sm);
  cursor:             pointer;
  transition:         transform var(--transition-fast);
}

.kmg-slider::-webkit-slider-thumb:active {
  transform: scale(1.2);
}

.kmg-slider::-moz-range-thumb {
  width:         44px;
  height:        44px;
  border-radius: 50%;
  background:    var(--color-primary);
  box-shadow:    var(--shadow-sm);
  border:        none;
  cursor:        pointer;
}