:root {
  color-scheme: dark;
  --ink: #080d18;
  --panel: #101827;
  --panel-hover: #141e30;
  --line: rgba(255, 255, 255, 0.11);
  --text: #f4f7fb;
  --muted: #9ba8ba;
  --accent: #e0bb61;
  --radius: 1.5rem;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }

html { background: var(--ink); }

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  color: var(--text);
  background:
    radial-gradient(circle at 12% -10%, rgba(42, 76, 129, 0.28), transparent 35rem),
    radial-gradient(circle at 92% 110%, rgba(187, 52, 57, 0.16), transparent 34rem),
    var(--ink);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.16;
  background-image: linear-gradient(rgba(255,255,255,.035) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,.035) 1px, transparent 1px);
  background-size: 3rem 3rem;
  mask-image: linear-gradient(to bottom, black, transparent 78%);
}

.page {
  width: min(92rem, 100%);
  margin: 0 auto;
  padding: clamp(2rem, 5vw, 4.75rem) clamp(1rem, 4vw, 3.5rem) 2.25rem;
  position: relative;
}

header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 2rem;
  align-items: end;
  margin-bottom: clamp(2rem, 4vw, 3.5rem);
}

.eyebrow {
  margin: 0 0 .8rem;
  color: var(--accent);
  font-size: .79rem;
  font-weight: 700;
  letter-spacing: .22em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-family: Georgia, "Noto Serif SC", "Songti SC", serif;
  font-size: clamp(2.9rem, 7vw, 6.7rem);
  font-weight: 500;
  line-height: .94;
  letter-spacing: -.055em;
}

.intro {
  max-width: 25rem;
  margin: 0 0 .35rem;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.7;
  text-align: right;
}

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

.flag-item {
  display: grid;
  grid-row: span 2;
  grid-template-rows: subgrid;
  min-width: 0;
}

.flag-card {
  min-width: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgba(255,255,255,.025), transparent 40%), var(--panel);
  box-shadow: 0 1.4rem 4rem rgba(0, 0, 0, .2);
  transition: transform .25s ease, border-color .25s ease, background-color .25s ease;
}

.flag-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, .2);
  background-color: var(--panel-hover);
}

.flag-button {
  appearance: none;
  width: 100%;
  min-height: 18rem;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: clamp(1.1rem, 3vw, 2rem);
  border: 0;
  border-bottom: 1px solid var(--line);
  color: inherit;
  background:
    radial-gradient(circle at 50% 35%, rgba(255,255,255,.08), transparent 46%),
    rgba(2, 7, 14, .34);
  cursor: zoom-in;
}

.flag-button:focus-visible,
.close-button:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: -5px;
}

.flag-visual {
  display: block;
  width: 100%;
  height: auto;
  max-height: 16.5rem;
  filter: drop-shadow(0 .8rem 1.1rem rgba(0, 0, 0, .32));
}

.flag-visual[data-ratio="2:1"] { aspect-ratio: 2 / 1; }
.flag-visual[data-ratio="3:2"] { aspect-ratio: 3 / 2; }

.card-copy {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 1rem;
  align-items: end;
  padding: 1.25rem 1.35rem 1.35rem;
}

.index {
  display: block;
  margin-bottom: .5rem;
  color: var(--muted);
  font-size: .76rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: .16em;
}

h2 {
  margin: 0;
  font-size: clamp(1.1rem, 2vw, 1.35rem);
  font-weight: 650;
  letter-spacing: -.02em;
}

.ratio {
  display: inline-flex;
  align-items: center;
  min-height: 2rem;
  padding: .35rem .7rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: #cbd3df;
  font-size: .78rem;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.footnote {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 1.25rem .2rem 0;
  color: var(--muted);
  font-size: .78rem;
  line-height: 1.5;
}

dialog {
  width: min(70rem, calc(100% - 2rem));
  padding: 0;
  border: 1px solid rgba(255,255,255,.16);
  border-radius: 1.6rem;
  color: var(--text);
  background: #0d1522;
  box-shadow: 0 2rem 7rem rgba(0,0,0,.65);
}

dialog::backdrop {
  background: rgba(1, 4, 10, .82);
  backdrop-filter: blur(12px);
}

.dialog-stage {
  min-height: min(65vh, 38rem);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: clamp(1.25rem, 5vw, 4rem);
  background: radial-gradient(circle at center, rgba(255,255,255,.07), transparent 58%);
}

.dialog-stage .flag-visual {
  width: min(100%, 58rem);
  max-height: 65vh;
}

.dialog-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 1.15rem 1rem 1.4rem;
  border-top: 1px solid var(--line);
}

.dialog-name { font-size: 1rem; font-weight: 650; }

.close-button {
  min-width: 5.25rem;
  min-height: 2.65rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  background: rgba(255,255,255,.06);
  font: inherit;
  cursor: pointer;
}

.close-button:hover { background: rgba(255,255,255,.11); }

.music-card {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(16rem, 28rem);
  gap: 1.25rem 2rem;
  align-items: center;
  margin-bottom: 1.5rem;
  padding: clamp(1.25rem, 3vw, 2rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(120deg, rgba(224,187,97,.07), transparent 65%), var(--panel);
}

.music-card[hidden] { display: none; }
.music-card h2 { font-size: clamp(1.35rem, 3vw, 1.9rem); }
.music-credit { margin: .65rem 0 0; color: var(--muted); font-size: .9rem; }
.music-player { min-width: 0; }
.music-player audio { display: block; width: 100%; }
.music-status { margin: .75rem 0 0; color: var(--muted); font-size: .85rem; line-height: 1.6; }
.music-start {
  margin-top: .75rem;
  padding: .65rem 1.15rem;
  border: 1px solid var(--accent);
  border-radius: 999px;
  color: var(--ink);
  background: var(--accent);
  font: inherit;
  font-weight: 650;
  cursor: pointer;
}
.music-start[hidden] { display: none; }
.music-source { grid-column: 1 / -1; margin: 0; color: var(--muted); font-size: .75rem; line-height: 1.7; }
.music-source summary { width: fit-content; cursor: pointer; }
.music-source p { margin: .65rem 0 0; }
.music-source summary:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }
.music-source a { color: #cbd3df; text-underline-offset: .2em; }
.music-start:focus-visible,
.music-source a:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }

.mini-player {
  grid-column: auto;
  min-width: 0;
  padding: .85rem 1rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: var(--panel);
}

.mini-player h3 {
  margin: 0 0 .6rem;
  color: var(--accent);
  font-size: .85rem;
  font-weight: 650;
}

.mini-player audio { display: block; width: 100%; height: 2.5rem; }

.letter-section {
  margin-top: clamp(2.5rem, 5vw, 4.5rem);
  padding-top: clamp(2rem, 4vw, 3rem);
  border-top: 1px solid var(--line);
}

.letter-heading { margin-bottom: 1.5rem; }

.letter-heading h2 {
  font-family: Georgia, "Noto Serif TC", "Songti TC", serif;
  font-size: clamp(1.8rem, 4vw, 3rem);
  font-weight: 500;
}

.letter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  column-gap: 1rem;
  row-gap: 0;
}

.letter-card {
  display: grid;
  grid-row: span 13;
  grid-template-rows: subgrid;
  min-width: 0;
  padding: clamp(1.25rem, 3vw, 2.25rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgba(255,255,255,.025), transparent 40%), var(--panel);
  box-shadow: 0 1.4rem 4rem rgba(0, 0, 0, .16);
  font-size: 1rem;
  line-height: 1.85;
  overflow-wrap: anywhere;
}

.letter-language {
  margin: 0 0 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--line);
  color: var(--accent);
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .14em;
}

.letter-card p { margin: 0 0 1.25rem; }
.letter-card p:last-child { margin-bottom: 0; }
.letter-card .letter-salutation { font-weight: 650; }
.letter-card ol {
  display: grid;
  grid-row: span 7;
  grid-template-rows: subgrid;
  margin: 1.5rem 0;
  padding-left: 1.6rem;
}
.letter-card li { margin-bottom: .9rem; padding-left: .25rem; }
.letter-card li:last-child { margin-bottom: 0; }
.letter-card li::marker { color: var(--accent); font-weight: 650; }
.letter-card strong { font-weight: 650; }

@media (max-width: 900px) {
  .flag-item { grid-row: auto; grid-template-rows: auto; gap: 1rem; }
  .mini-player { grid-column: 1; }
  .music-card { grid-template-columns: 1fr; }
  .letter-grid { grid-template-columns: 1fr; gap: 1rem; }
  .letter-card,
  .letter-card ol { display: block; grid-row: auto; }
  header { grid-template-columns: 1fr; gap: 1rem; }
  .intro { text-align: left; }
  .gallery { grid-template-columns: 1fr; }
  .flag-button { min-height: 15rem; }
  .flag-visual { max-width: 42rem; max-height: 22rem; }
}

@media (max-width: 480px) {
  .page { padding-inline: .75rem; }
  .flag-button { min-height: 12rem; padding: 1rem; }
  .card-copy { padding: 1rem; }
  .footnote { flex-direction: column; gap: .25rem; margin-inline: .25rem; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}