:root {
  --ink: #1C2321;
  --panel: #262E2B;
  --panel-raised: #2E3733;
  --paper: #F4F1E8;
  --paper-dim: #B7C0B8;
  --amber: #F2A65A;
  --amber-dim: #8A6238;
  --teal: #5FB3A3;
  --line: #3A443F;
  --radius: 14px;
  --mono: 'JetBrains Mono', ui-monospace, monospace;
  --sans: 'Inter', system-ui, sans-serif;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--sans);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.grain {
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.035;
  z-index: 1;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

.wrap {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.top {
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  background: rgba(28, 35, 33, 0.9);
  backdrop-filter: blur(8px);
  z-index: 10;
}

.top-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 18px;
  padding-bottom: 18px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--mono);
  font-weight: 700;
  letter-spacing: 0.08em;
  font-size: 15px;
}

.brand-mark {
  color: var(--amber);
  font-size: 18px;
}

.top-nav {
  display: flex;
  align-items: center;
  gap: 24px;
}

.top-nav a {
  color: var(--paper-dim);
  text-decoration: none;
  font-size: 14px;
}

.top-nav a:hover, .top-nav a:focus-visible {
  color: var(--amber);
}

.lang-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  line-height: 1;
  background: transparent;
  border: 1px solid var(--line);
  padding: 4px 7px;
  border-radius: 6px;
  cursor: pointer;
  transition: border-color 0.15s ease;
}

.lang-toggle:hover, .lang-toggle:focus-visible {
  border-color: var(--teal);
  color: var(--paper);
}

/* Hero */
.hero {
  padding-top: 56px;
  padding-bottom: 28px;
  text-align: center;
}

.eyebrow {
  font-family: var(--mono);
  color: var(--teal);
  text-transform: uppercase;
  letter-spacing: 0.14em;
  font-size: 12px;
  margin: 0 0 14px;
}

.hero h1 {
  font-size: clamp(32px, 6vw, 46px);
  margin: 0 0 12px;
  letter-spacing: -0.01em;
}

.hero .sub {
  color: var(--paper-dim);
  max-width: 44ch;
  margin: 0 auto;
  font-size: 16px;
}

/* Tabs */
.tabs {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 20px;
}

.tab {
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.02em;
  background: transparent;
  border: 1px solid var(--line);
  color: var(--paper-dim);
  padding: 9px 18px;
  border-radius: 999px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease, background 0.15s ease;
}

.tab:hover { color: var(--paper); }

.tab.active {
  background: var(--amber);
  border-color: var(--amber);
  color: var(--ink);
  font-weight: 700;
}

/* Card */
.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 64px;
  box-shadow: 0 30px 60px -30px rgba(0,0,0,0.6);
}

.times {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 16px;
  align-items: end;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-width:0;
}

.field label {
  font-family: var(--mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--paper-dim);
}

.field input[type="time"],
.field input[type="datetime-local"] {
  background: var(--panel-raised);
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--paper);
  font-family: var(--mono);
  font-size: 22px;
  padding: 12px 14px;
  width: 100%;
  color-scheme: dark;
  text-align: left;
}

/* iOS/Safari ignores author padding on the right edge of native date/time
   inputs unless the default appearance is stripped first. Scoped to iOS
   WebKit only (via -webkit-touch-callout, unsupported elsewhere) so
   Chrome/Android keep their native calendar/clock icon. */
@supports (-webkit-touch-callout: none) {
  .field input[type="time"],
  .field input[type="datetime-local"] {
    -webkit-appearance: none;
    appearance: none;
  }
}

.field input[type="time"]:focus-visible,
.field input[type="datetime-local"]:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 2px;
}

.field input[type="datetime-local"] {
  font-size: clamp(13px, 4.2vw, 22px);
}

.swap {
  background: var(--panel-raised);
  border: 1px solid var(--line);
  color: var(--amber);
  width: 42px;
  height: 42px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.2s ease, background 0.2s ease;
  margin-bottom: 2px;
}

.swap:hover { background: var(--amber-dim); }
.swap:active { transform: rotate(180deg); }
.swap:focus-visible { outline: 2px solid var(--amber); outline-offset: 2px; }

.quickrow {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 18px;
}

.chip {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--paper-dim);
  font-family: var(--sans);
  font-size: 13px;
  padding: 7px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.chip:hover { border-color: var(--amber); color: var(--paper); }

.chip.toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
}

.chip.toggle input { accent-color: var(--amber); }

/* Result / flipboard */
.result {
  margin-top: 36px;
  text-align: center;
}

.flipboard {
  display: inline-flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
}

.flip-group {
  display: flex;
  align-items: baseline;
  gap: 8px;
  background: var(--ink);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 20px;
}

.flip-value {
  font-family: var(--mono);
  font-weight: 800;
  font-size: clamp(34px, 8vw, 56px);
  color: var(--amber);
  transition: transform 0.18s ease, opacity 0.18s ease;
}

.flip-value.updating {
  animation: flap 0.32s ease;
}

@keyframes flap {
  0%   { transform: rotateX(0deg); opacity: 1; }
  40%  { transform: rotateX(90deg); opacity: 0.2; }
  55%  { transform: rotateX(90deg); opacity: 0.2; }
  100% { transform: rotateX(0deg); opacity: 1; }
}

.flip-unit {
  font-family: var(--mono);
  font-size: 16px;
  color: var(--paper-dim);
}

.overnight-note {
  margin-top: 14px;
  font-size: 13px;
  color: var(--teal);
  font-family: var(--mono);
}

.overnight-note.leap {
  color: var(--amber);
}

.overnight-note.error {
  color: #E88585;
}

.calendar-line {
  margin-top: 16px;
  font-size: 15px;
  color: var(--paper);
  font-family: var(--sans);
}

/* Sub stats */
.substats {
  margin-top: 28px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  border-top: 1px solid var(--line);
  padding-top: 24px;
}

.stat {
  text-align: center;
}

.stat-value {
  display: block;
  font-family: var(--mono);
  font-size: 20px;
  color: var(--teal);
  font-weight: 600;
}

.stat-label {
  display: block;
  font-size: 12px;
  color: var(--paper-dim);
  margin-top: 4px;
}

/* Actions */
.actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-top: 28px;
  flex-wrap: wrap;
}

.btn {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 14px;
  padding: 12px 22px;
  border-radius: 10px;
  border: 1px solid var(--amber);
  background: var(--amber);
  color: var(--ink);
  cursor: pointer;
  transition: transform 0.12s ease, background 0.15s ease;
}

.btn:hover { transform: translateY(-1px); }
.btn.ghost {
  background: transparent;
  color: var(--paper);
  border-color: var(--line);
}
.btn.ghost:hover { border-color: var(--amber); color: var(--amber); }

.copy-feedback {
  text-align: center;
  min-height: 20px;
  font-size: 13px;
  color: var(--teal);
  margin-top: 10px;
  font-family: var(--mono);
}

/* Info sections */
.info {
  padding: 20px 0 44px;
  border-top: 1px solid var(--line);
}

.info h2 {
  font-size: 22px;
  margin-bottom: 14px;
}

.info h3 {
  font-size: 17px;
  margin-top: 26px;
  margin-bottom: 8px;
}

.info p {
  color: var(--paper-dim);
  font-size: 15px;
}

.mono { font-family: var(--mono); color: var(--paper); }
.muted { color: var(--paper-dim); }

.example {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px 20px;
  margin-top: 16px;
}

.example-label {
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--teal);
  margin: 0 0 8px;
}

.example p { color: var(--paper); margin: 0; }

details {
  border-bottom: 1px solid var(--line);
  padding: 14px 0;
}

summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--paper);
  list-style: none;
}

summary::-webkit-details-marker { display: none; }

summary::before {
  content: "+";
  color: var(--amber);
  font-family: var(--mono);
  margin-right: 10px;
}

details[open] summary::before {
  content: "–";
}

details p {
  margin-top: 10px;
  margin-bottom: 0;
}

/* Footer */
.foot {
  border-top: 1px solid var(--line);
  padding: 28px 0 40px;
}

.foot p {
  color: var(--paper-dim);
  font-size: 13px;
  margin: 0;
}
#panel-date .times {
  gap: 10px;
}

#panel-date .swap {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
}

#panel-date {
  padding-left: 20px;
  padding-right: 20px;
}

#panel-date .field input[type="datetime-local"] {
  padding-left: 10px;
  padding-right: 6px;
}
/* Responsive */
@media (max-width: 560px) {
  .top-inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding-top: 14px;
    padding-bottom: 14px;
  }
  .top-nav {
    gap: 16px;
  }
  .top-nav a {
    font-size: 13px;
    white-space: nowrap;
  }
  .times {
    grid-template-columns: 1fr;
  }
  .swap {
    justify-self: center;
    margin: 4px 0;
  }
  .substats {
    grid-template-columns: 1fr;
    gap: 18px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .flip-value.updating { animation: none; }
  .swap:active { transform: none; }
  html { scroll-behavior: auto; }
}