:root {
  /* surfaces: violet-blue near-black ramp, depth = lightness */
  --bg: oklch(0.148 0.018 285);
  --surface: oklch(0.192 0.02 285);
  --surface-2: oklch(0.24 0.022 285);
  --hairline: oklch(0.32 0.02 285);
  /* ink */
  --ink: oklch(0.93 0.006 285);
  --ink-muted: oklch(0.72 0.012 285);
  --ink-faint: oklch(0.56 0.014 285);
  /* accent: volt — energy, positives, the score */
  --volt: oklch(0.87 0.21 128);
  --volt-dim: oklch(0.62 0.14 128);
  --volt-wash: oklch(0.87 0.21 128 / 0.09);
  /* sleep stages */
  --stage-deep: oklch(0.56 0.19 293);
  --stage-light: oklch(0.66 0.13 255);
  --stage-rem: oklch(0.76 0.13 195);
  --stage-awake: oklch(0.72 0.17 42);
  /* semantic */
  --warn: oklch(0.78 0.16 75);
  --bad: oklch(0.68 0.19 25);
  /* type scale, fixed rem, ratio 1.2 */
  --text-xs: 0.694rem;
  --text-sm: 0.833rem;
  --text-base: 1rem;
  --text-lg: 1.2rem;
  --text-xl: 1.44rem;
  --text-2xl: 2.074rem;
  --text-display: 4.3rem;
  /* spacing, 4pt scale */
  --sp-1: 0.25rem; --sp-2: 0.5rem; --sp-3: 0.75rem; --sp-4: 1rem;
  --sp-6: 1.5rem; --sp-8: 2rem; --sp-12: 3rem;
  --font-ui: 'Barlow', -apple-system, 'Segoe UI', system-ui, sans-serif;
  --font-display: 'Barlow Semi Condensed', 'Barlow', 'Arial Narrow', sans-serif;
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { color-scheme: dark; }
body {
  margin: 0;
  background: var(--bg);
  background-image: radial-gradient(ellipse 900px 600px at 50% -80px, oklch(0.87 0.21 128 / 0.04) 0%, transparent 70%);
  color: var(--ink);
  font-family: var(--font-ui);
  font-size: var(--text-base);
  line-height: 1.55;
  letter-spacing: 0.012em;
  -webkit-font-smoothing: antialiased;
}

/* ---------- shell ---------- */
body::before {
  content: '';
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent 0%, var(--volt) 40%, var(--volt) 60%, transparent 100%);
  opacity: 0.7;
  z-index: 10;
  pointer-events: none;
}

.top {
  display: flex;
  align-items: center;
  gap: var(--sp-8);
  max-width: 1180px;
  margin-inline: auto;
  padding: var(--sp-4) max(var(--sp-4), env(safe-area-inset-left), env(safe-area-inset-right));
  border-bottom: 1px solid var(--hairline);
}
.brand {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  display: flex;
  align-items: center;
  gap: var(--sp-2);
}
.brand::after {
  content: '';
  display: block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--volt);
  box-shadow: 0 0 8px var(--volt);
  flex-shrink: 0;
}
.top nav { display: flex; gap: var(--sp-4); }
.top nav a {
  color: var(--ink-muted);
  text-decoration: none;
  font-weight: 600;
  font-size: var(--text-sm);
  padding: var(--sp-2) var(--sp-1);
  border-bottom: 2px solid transparent;
}
.top nav a.active {
  color: var(--volt);
  border-bottom-color: var(--volt);
}
.top nav a:focus-visible { outline: 2px solid var(--volt); outline-offset: 3px; border-radius: 2px; }

main {
  max-width: 1180px;
  margin-inline: auto;
  padding-inline: max(var(--sp-4), env(safe-area-inset-left), env(safe-area-inset-right));
  padding-bottom: var(--sp-8);
}
footer {
  max-width: 1180px;
  margin-inline: auto;
  padding: 0 var(--sp-4) max(var(--sp-8), env(safe-area-inset-bottom));
  font-size: var(--text-xs);
  color: var(--ink-faint);
}

/* ---------- section heads ---------- */
.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--sp-4);
  margin-bottom: var(--sp-3);
}
h2 {
  font-family: var(--font-display);
  font-size: var(--text-base);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
  margin: 0;
  text-wrap: balance;
}
.hint { margin: 0; font-size: var(--text-xs); color: var(--ink-faint); }

/* ---------- error ---------- */
.error {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  margin-top: var(--sp-6);
  padding: var(--sp-4);
  border: 1px solid var(--bad);
  border-radius: 10px;
  background: oklch(0.68 0.19 25 / 0.08);
}
.error p { margin: 0; }
.error button {
  font: inherit; font-weight: 600;
  color: var(--bg);
  background: var(--ink);
  border: 0; border-radius: 8px;
  padding: var(--sp-2) var(--sp-4);
  cursor: pointer;
}

/* ---------- trend ---------- */
.trend { margin-top: var(--sp-6); }
#trend-chart { width: 100%; height: 230px; }

/* ---------- day ---------- */
.day { margin-top: var(--sp-8); }
.day-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
  margin-bottom: var(--sp-4);
}
h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  text-wrap: balance;
}
h1 .weekday { color: var(--ink-muted); font-size: var(--text-lg); font-weight: 700; margin-left: var(--sp-2); }
.day-nav { display: flex; gap: var(--sp-2); }
.day-nav button {
  font: inherit;
  width: 44px; height: 44px;
  display: grid; place-items: center;
  color: var(--ink);
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: 10px;
  cursor: pointer;
  transition: background 150ms var(--ease-out), border-color 150ms var(--ease-out), color 150ms var(--ease-out);
}
.day-nav button:hover:not(:disabled) { background: var(--surface-2); border-color: var(--ink-faint); color: var(--volt); }
.day-nav button:active:not(:disabled) { transform: scale(0.94); }
.day-nav button:focus-visible { outline: 2px solid var(--volt); outline-offset: 2px; }
.day-nav button:disabled { color: var(--ink-faint); cursor: default; opacity: 0.4; }

/* ---------- hero ---------- */
.hero {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--sp-6) var(--sp-12);
  align-items: center;
  padding: var(--sp-6);
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: 14px;
  box-shadow:
    0 4px 32px oklch(0 0 0 / 0.35),
    inset 0 1px 0 oklch(0.87 0.21 128 / 0.12);
}
.score {
  display: grid;
  grid-template-columns: auto auto;
  align-items: center;
  gap: var(--sp-4);
}
.score svg {
  display: block;
  filter: drop-shadow(0 0 14px oklch(0.87 0.21 128 / 0.4));
}
.score .num {
  font-family: var(--font-display);
  font-size: var(--text-display);
  font-weight: 800;
  line-height: 0.9;
  color: var(--volt);
  font-variant-numeric: tabular-nums;
  text-shadow: 0 0 40px oklch(0.87 0.21 128 / 0.5);
}
.score .meta { display: grid; gap: var(--sp-1); justify-items: start; }
.score .label { font-size: var(--text-sm); color: var(--ink-muted); }
.qualifier {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--volt);
  background: var(--volt-wash);
  border: 1px solid var(--volt-dim);
  border-radius: 999px;
  padding: 0.1rem 0.7rem;
  display: inline-block;
}
@keyframes popIn {
  0%   { transform: scale(0.7); opacity: 0; }
  70%  { transform: scale(1.06); }
  100% { transform: scale(1); opacity: 1; }
}
.qualifier:not([hidden]) { animation: popIn 300ms var(--ease-out) both; }
#ring-arc { transition: stroke-dashoffset 600ms var(--ease-out); }

.stages { display: grid; gap: var(--sp-3); min-width: 0; }
.duration-line {
  font-size: var(--text-lg);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}
.duration-line small { color: var(--ink-muted); font-size: var(--text-sm); font-weight: 400; }
.window { font-size: var(--text-sm); color: var(--ink-muted); font-variant-numeric: tabular-nums; }
.stage-bar {
  display: flex;
  height: 18px;
  border-radius: 9px;
  overflow: hidden;
  gap: 2px;
}
.stage-bar span { min-width: 3px; }
.stage-legend {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-6);
  font-size: var(--text-sm);
  font-variant-numeric: tabular-nums;
}
.stage-legend .item { display: flex; align-items: baseline; gap: var(--sp-2); }
.stage-legend .dot { width: 9px; height: 9px; border-radius: 3px; align-self: center; }
.stage-legend .name { color: var(--ink-muted); }
.stage-legend .val { font-weight: 600; }
.stage-legend .pct { color: var(--ink-faint); }

/* ---------- timeline ---------- */
.timeline { margin-top: var(--sp-8); }

.stage-viz {
  display: grid;
  grid-template-columns: 64px 1fr;
  padding-right: 16px;
  margin-bottom: var(--sp-3);
}
.sv-labels { position: relative; }
.sv-bars { position: relative; }

#day-chart { width: 100%; height: 420px; }

.sleep-need {
  margin: var(--sp-2) 0 0;
  font-size: var(--text-sm);
  color: var(--ink-muted);
}
.sleep-need strong { color: var(--ink); font-weight: 600; }

/* ---------- vitals ---------- */
.vitals { margin-top: var(--sp-8); }
.vitals-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  column-gap: var(--sp-12);
  position: relative;
}
.vitals-grid::before {
  content: '';
  position: absolute;
  left: 50%;
  top: 0; bottom: 0;
  width: 1px;
  background: var(--hairline);
  transform: translateX(-50%);
}
@media (max-width: 760px) { .vitals-grid::before { display: none; } }
.vitals-grid dl {
  margin: 0;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: baseline;
  align-content: start;
}
.vitals-grid .row {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: subgrid;
  padding-block: var(--sp-3);
  padding-inline: var(--sp-2);
  border-bottom: 1px solid var(--hairline);
  margin-inline: calc(-1 * var(--sp-2));
  border-radius: 6px;
  transition: background 140ms var(--ease-out);
}
.vitals-grid .row:hover { background: var(--surface-2); }
.vitals-grid .row:last-child { border-bottom: none; }
.vitals-grid dt { font-size: var(--text-sm); color: var(--ink-muted); }
.vitals-grid dt .tag {
  margin-left: var(--sp-2);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--volt);
}
.vitals-grid dd {
  margin: 0;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  font-size: var(--text-lg);
  text-align: right;
}
.vitals-grid dd small { color: var(--ink-faint); font-size: var(--text-sm); font-weight: 400; margin-left: 2px; }
.vitals-grid dd .extra { color: var(--warn); font-size: var(--text-sm); font-weight: 500; margin-left: var(--sp-2); }
.vitals-grid dd .delta { font-size: var(--text-sm); font-weight: 500; margin-left: var(--sp-2); color: var(--ink-faint); }
.vitals-grid dd .delta.up { color: var(--volt); }
.vitals-grid dd .delta.down { color: var(--warn); }

/* ---------- transitions ---------- */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
.hero.loaded { animation: fadeUp 380ms var(--ease-out) both; }

@keyframes slideIn {
  from { opacity: 0; transform: translateX(-8px); }
  to   { opacity: 1; transform: translateX(0); }
}
.row-anim { animation: slideIn 240ms var(--ease-out) both; }

/* ---------- skeleton ---------- */
.skeleton { position: relative; overflow: hidden; background: var(--surface); border-radius: 10px; }
.skeleton::after {
  content: '';
  position: absolute; inset: 0;
  background: linear-gradient(100deg, transparent 30%, oklch(0.3 0.02 285 / 0.5) 50%, transparent 70%);
  animation: shimmer 1.4s infinite;
}
.skeleton-text { color: transparent; }
@keyframes shimmer { from { transform: translateX(-100%); } to { transform: translateX(100%); } }

/* ---------- responsive ---------- */
@media (min-width: 761px) {
  .score svg { width: 152px; height: 152px; }
}

@media (max-width: 760px) {
  :root { --text-display: 3.2rem; --text-2xl: 1.6rem; }
  .top { gap: var(--sp-4); }
  .hero { grid-template-columns: 1fr; padding: var(--sp-4); }
  #trend-chart { height: 190px; }
  #day-chart { height: 320px; }
  .vitals-grid { column-gap: var(--sp-6); }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  .skeleton::after { animation: none; }
  .hero.loaded { animation: none; opacity: 1; transform: none; }
  .row-anim { animation: none; opacity: 1; transform: none; }
}