/* ==========================================================================
   Spotifaux — styles.css
   Clean, accessible UI for ABX testing with zero-network trial flow
   ========================================================================== */

/* Design tokens */
:root {
  --bg: #0c0f14;
  --panel: #121824;
  --panel-2: #0f1420;
  --text: #e7edf5;
  --muted: #a1a9b6;
  --accent: #18c37e;        /* friendly green-teal, not Spotify green */
  --accent-600: #10a26a;
  --accent-700: #0e8f5e;
  --accent-800: #0b7a51;
  --danger: #ff5470;
  --ok: #6ae38c;
  --warning: #ffd166;
  --border: #223049;
  --radius: 16px;
  --radius-sm: 10px;
  --gap: 16px;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
  --shadow-soft: 0 6px 20px rgba(0,0,0,.25);
  --font: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Inter, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji";
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  --maxw: 1040px;
  --trans: 180ms cubic-bezier(.2,.7,.2,1);
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f7f9fc;
    --panel: #ffffff;
    --panel-2: #f1f4f9;
    --text: #0e1525;
    --muted: #4a5465;
    --border: #d9e1ef;
    --shadow: 0 10px 24px rgba(15, 23, 42, .08);
    --shadow-soft: 0 6px 16px rgba(15, 23, 42, .06);
  }
}

/* Base reset (minimal) */
*,
*::before,
*::after { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  background: radial-gradient(1200px 700px at 10% -10%, rgba(24,195,126,.08), transparent 50%),
              radial-gradient(900px 600px at 90% 10%, rgba(80,160,255,.07), transparent 40%),
              var(--bg);
  color: var(--text);
  font: 16px/1.5 var(--font);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, svg, video { display: block; max-width: 100%; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

:focus-visible {
  outline: 2px solid color-mix(in oklab, var(--accent) 80%, white 20%);
  outline-offset: 2px;
  border-radius: 6px;
}

/* Layout */
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 24px clamp(16px, 4vw, 32px);
}

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 20px;
}

.brand {
  display: flex; align-items: center; gap: 12px;
  font-weight: 800; letter-spacing: .2px;
}
.brand .logo {
  width: 36px; height: 36px; border-radius: 50%;
  background: linear-gradient(145deg, var(--accent), #39ffd0);
  box-shadow: 0 0 0 6px color-mix(in oklab, var(--accent) 35%, transparent);
}
.brand .name { font-size: 1.15rem; }
.tagline { color: var(--muted); font-size: .95rem; }

.main {
  display: grid;
  gap: 20px;
}

.section {
  background: linear-gradient(180deg, color-mix(in oklab, var(--panel) 90%, transparent), var(--panel));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
  padding: clamp(16px, 3vw, 24px);
}

/* Loader */
.loader {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  background: var(--bg);
  z-index: 1000;
}

.loader-card {
  width: min(500px, 92vw);
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.loader h1 {
  margin: 0 0 6px 0;
  font-size: 1.25rem;
}

.progress-wrap {
  width: 100%;
  height: 10px;
  background: color-mix(in oklab, var(--panel-2) 80%, black 20%);
  border-radius: 999px;
  border: 1px solid var(--border);
  overflow: hidden;
  margin: 12px 0 8px 0;
}

#progress.bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), #3ee2b0 50%, var(--accent));
  background-size: 200% 100%;
  animation: shimmer 1.4s linear infinite;
  border-radius: 999px;
}
@keyframes shimmer {
  to { background-position: -200% 0; }
}

.loader .hint {
  color: var(--muted);
  font-size: .9rem;
}

/* Reveal app when ready */
.app { display: none; }
body.ready .app { display: block; }
body.ready .loader { display: none; }

/* Cards / panels */
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
  padding: 16px;
}
.card + .card { margin-top: 12px; }

.card-header { display:flex; align-items:center; justify-content:space-between; gap:12px; margin-bottom:8px; }
.card-title { font-weight: 700; font-size: 1.05rem; }
.card-subtle { color: var(--muted); font-size: .92rem; }

/* ABX Controls */
.abx-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}
@media (min-width: 720px) {
  .abx-grid { grid-template-columns: 1.2fr .8fr; }
}

.playpad {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(3, minmax(0,1fr));
}

.playpad .btn {
  padding-block: 14px;
  font-size: 1.05rem;
}

.play-labels {
  display: flex; align-items: center; justify-content: space-between;
  color: var(--muted); font-size: .92rem;
  margin-top: 4px;
}

.choice {
  display: grid;
  gap: 12px;
  align-content: start;
}

.segmented {
  display: grid;
  grid-template-columns: 1fr 1fr;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 4px;
}

.segmented .seg {
  border: 0;
  background: transparent;
  color: var(--text);
  padding: 10px 14px;
  border-radius: 999px;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--trans), transform var(--trans), box-shadow var(--trans);
}
.segmented .seg[aria-pressed="true"] {
  background: linear-gradient(180deg, color-mix(in oklab, var(--accent) 20%, var(--panel) 80%), var(--panel));
  box-shadow: inset 0 0 0 1px color-mix(in oklab, var(--accent) 40%, var(--panel)), 0 4px 12px rgba(0,0,0,.25);
}
.segmented .seg:active { transform: translateY(1px); }

.confidence {
  display: grid;
  gap: 8px;
}
.confidence label { color: var(--muted); font-size: .92rem; }

input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 18px;
  background: transparent;
}
input[type="range"]::-webkit-slider-runnable-track {
  height: 8px;
  background: linear-gradient(180deg, var(--panel-2), color-mix(in oklab, var(--panel-2) 70%, black 30%));
  border-radius: 999px;
  border: 1px solid var(--border);
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  margin-top: -6px; /* centers thumb on track */
  width: 20px; height: 20px; border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, #fff, #bbb);
  border: 2px solid color-mix(in oklab, var(--accent) 70%, black 30%);
  box-shadow: 0 2px 8px rgba(0,0,0,.25);
}
input[type="range"]::-moz-range-track {
  height: 8px;
  background: linear-gradient(180deg, var(--panel-2), color-mix(in oklab, var(--panel-2) 70%, black 30%));
  border-radius: 999px;
  border: 1px solid var(--border);
}
input[type="range"]::-moz-range-thumb {
  width: 20px; height: 20px; border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, #fff, #bbb);
  border: 2px solid color-mix(in oklab, var(--accent) 70%, black 30%);
  box-shadow: 0 2px 8px rgba(0,0,0,.25);
}

/* Buttons */
.btn {
  --btn-bg: var(--panel-2);
  --btn-fg: var(--text);
  --btn-bd: var(--border);
  display: inline-flex; align-items: center; justify-content: center;
  gap: 8px;
  height: 44px;
  padding: 0 14px;
  border-radius: 12px;
  border: 1px solid var(--btn-bd);
  background: var(--btn-bg);
  color: var(--btn-fg);
  font-weight: 700;
  letter-spacing: .2px;
  cursor: pointer;
  transition: transform var(--trans), box-shadow var(--trans), background var(--trans), border-color var(--trans), color var(--trans), opacity var(--trans);
  user-select: none;
  text-align: center;
  white-space: nowrap;
}
.btn:hover { box-shadow: 0 6px 14px rgba(0,0,0,.18); transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn[disabled], .btn[aria-disabled="true"] { opacity: .6; cursor: not-allowed; box-shadow: none; }

.btn--primary {
  --btn-bg: linear-gradient(180deg, color-mix(in oklab, var(--accent) 40%, #fff 0%), var(--accent-600));
  --btn-bd: color-mix(in oklab, var(--accent) 65%, black 35%);
  color: #072012;
}
.btn--ghost {
  --btn-bg: transparent;
  --btn-bd: var(--border);
}
.btn--outline {
  --btn-bg: transparent;
  --btn-bd: color-mix(in oklab, var(--accent) 60%, var(--border));
  color: var(--accent);
}
.btn--danger {
  --btn-bg: linear-gradient(180deg, color-mix(in oklab, var(--danger) 40%, #fff 0%), #e04560);
  --btn-bd: color-mix(in oklab, var(--danger) 65%, black 35%);
  color: #2a0a12;
}

.btn--xl { height: 52px; padding-inline: 18px; font-size: 1.1rem; border-radius: 14px; }
.btn--icon { width: 44px; padding: 0; }

/* Pills & badges */
.badge {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: .85rem; padding: 6px 10px; border-radius: 999px;
  background: var(--panel-2); border: 1px solid var(--border);
  color: var(--muted);
}

/* Stats */
.stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}
@media (min-width: 720px) {
  .stats { grid-template-columns: repeat(4, 1fr); }
}
.stat {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px;
  box-shadow: var(--shadow-soft);
}
.stat .label { color: var(--muted); font-size: .85rem; }
.stat .value { font-weight: 800; font-size: 1.35rem; margin-top: 2px; }

/* Tables (for per-song stats) */
.table {
  width: 100%;
  border-collapse: collapse;
  overflow: hidden;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--panel);
}
.table th, .table td {
  padding: 12px 14px; text-align: left; border-bottom: 1px solid var(--border);
}
.table th { color: var(--muted); font-weight: 700; font-size: .9rem; }
.table tr:last-child td { border-bottom: 0; }
.table tr:hover td { background: color-mix(in oklab, var(--panel) 85%, black 15%); }

/* Footnotes / helper text */
.help { color: var(--muted); font-size: .9rem; }
.kbd {
  font-family: var(--mono);
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-bottom-width: 3px;
  padding: 0 6px; border-radius: 6px; font-size: .85rem;
}

/* Alerts */
.alert {
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  background: color-mix(in oklab, var(--panel) 92%, var(--accent) 8%);
  border-radius: 10px;
  padding: 12px 14px;
}
.alert--warn { border-left-color: var(--warning); }
.alert--danger { border-left-color: var(--danger); }

/* Footer */
.footer {
  margin-top: 32px;
  color: var(--muted);
  font-size: .9rem;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
}

/* Utilities */
.hidden { display: none !important; }
.center { text-align: center; }
.right { text-align: right; }
.stack { display: grid; gap: var(--gap); }
.row { display:flex; flex-wrap:wrap; gap:12px; align-items:center; }
.spacer { height: 20px; }
.hr { height: 1px; background: var(--border); border: 0; margin: 8px 0; }

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

/* Animations & motion preferences */
.fade-in {
  animation: fadeIn .4s var(--trans);
}
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}

/* Safe area for mobile */
@supports (padding: max(0px)) {
  .container { padding-left: max(16px, env(safe-area-inset-left)); padding-right: max(16px, env(safe-area-inset-right)); }
}

/* Example header hero (optional) */
.hero {
  background: linear-gradient(180deg, color-mix(in oklab, var(--panel) 70%, transparent), transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: clamp(20px, 4vw, 32px);
  display: grid; gap: 12px;
  box-shadow: var(--shadow-soft);
}
.hero h1 { margin: 0; font-size: clamp(1.4rem, 2vw + 1rem, 2rem); letter-spacing: .2px; }
.hero p { margin: 0; color: var(--muted); }

/* Toast (optional feedback) */
.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%);
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  padding: 10px 14px;
  display: none;
}
.toast.show { display: block; }

/* =======================================================================
   Example wiring suggestions (HTML classes this CSS expects)
   - .loader .loader-card -> #progress.bar (width set via JS)
   - .abx-grid -> .playpad (three play buttons) + .choice (segmented A/B + Submit)
   - .confidence -> input[type=range] for “How sure are you?”
   ======================================================================= */