:root {
  --bg: #0b0d10;
  --card: #14171c;
  --card-hi: #1a1e25;
  --line: #232830;
  --text: #e9ecf1;
  --muted: #868e9c;
  --dim: #5b626e;
  --free: #3ddc84;
  --free-dim: #1e6b43;
  --busy: #f0865a;
  --radius: 14px;
  --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f4f5f7;
    --card: #ffffff;
    --card-hi: #f7f8fa;
    --line: #e3e6eb;
    --text: #14171c;
    --muted: #5f6673;
    --dim: #9aa1ad;
    --free: #0f9d58;
    --free-dim: #8fd3ae;
    --busy: #c2542a;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  padding: 0 0 env(safe-area-inset-bottom);
  background: var(--bg);
  color: var(--text);
  font: 16px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC",
        "Hiragino Sans", "Microsoft JhengHei", sans-serif;
  -webkit-font-smoothing: antialiased;
}

/* ---------- 顶部 ---------- */

.top {
  position: sticky;
  top: 0;
  z-index: 10;
  padding: calc(env(safe-area-inset-top) + 14px) 18px 12px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}

.top-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
}

h1 {
  margin: 0;
  font-size: 21px;
  font-weight: 650;
  letter-spacing: -0.01em;
}

.clock {
  font: 600 20px/1 var(--mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

.sub {
  margin-top: 5px;
  font-size: 13px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

/* ---------- 提示条 ---------- */

.notice {
  margin: 12px 18px 0;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid color-mix(in srgb, var(--busy) 40%, var(--line));
  background: color-mix(in srgb, var(--busy) 10%, transparent);
  color: var(--text);
  font-size: 13px;
  line-height: 1.45;
}

.notice.holiday {
  border-color: color-mix(in srgb, var(--free) 40%, var(--line));
  background: color-mix(in srgb, var(--free) 8%, transparent);
}

/* ---------- 楼栋卡片 ---------- */

main {
  padding: 14px 18px 8px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.bld {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--card);
  overflow: hidden;
}

.bld-head {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 15px;
  background: none;
  border: 0;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.bld-head:active { background: var(--card-hi); }

.code {
  font: 600 12px/1 var(--mono);
  color: var(--muted);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 4px 6px;
  min-width: 26px;
  text-align: center;
}

.bld-name {
  flex: 1;
  font-size: 16px;
  font-weight: 550;
}

.free-count {
  font: 650 19px/1 var(--mono);
  font-variant-numeric: tabular-nums;
  color: var(--free);
}

.free-count .unit {
  font: 400 12px/1 system-ui, sans-serif;
  color: var(--muted);
  margin-left: 3px;
}

.chev {
  width: 0;
  height: 0;
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  border-top: 6px solid var(--dim);
  transition: transform .18s ease;
}

.bld.open .chev { transform: rotate(180deg); }

/* ---------- 教室列表 ---------- */

.rooms {
  list-style: none;
  margin: 0;
  padding: 0 15px;
  border-top: 1px solid var(--line);
  display: none;
}

.bld.open .rooms { display: block; }

.room {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 10px 0;
  border-bottom: 1px solid color-mix(in srgb, var(--line) 60%, transparent);
  font-size: 14px;
}

.room:last-child { border-bottom: 0; }

.room .rn {
  font: 600 14px/1.3 var(--mono);
  min-width: 62px;
  color: var(--text);
}

.room .rs {
  flex: 1;
  color: var(--muted);
  font-size: 13px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.room.is-free .rs { color: var(--free); }
.room.is-free .rs b { font-weight: 600; }

.room.is-busy .rn { color: var(--dim); }
.room.is-busy .rs { color: var(--dim); }

.room .tag {
  font: 500 11px/1 var(--mono);
  padding: 3px 6px;
  border-radius: 4px;
  border: 1px solid color-mix(in srgb, var(--free) 35%, var(--line));
  color: var(--free);
  white-space: nowrap;
}

.room.is-busy .tag {
  border-color: var(--line);
  color: var(--dim);
}

.empty-line {
  padding: 12px 0;
  font-size: 13px;
  color: var(--dim);
}

/* ---------- 页脚 ---------- */

footer {
  padding: 18px 18px 30px;
  font-size: 12px;
  line-height: 1.6;
  color: var(--dim);
}

footer p { margin: 0 0 3px; }
footer .dim { color: var(--dim); font-variant-numeric: tabular-nums; }

/* ---------- 宽屏 ---------- */

@media (min-width: 720px) {
  main {
    max-width: 720px;
    margin: 0 auto;
    padding: 20px 24px 8px;
  }
  .top { padding-left: max(18px, calc(50vw - 336px)); padding-right: max(18px, calc(50vw - 336px)); }
  footer { max-width: 720px; margin: 0 auto; }
  .notice { max-width: 684px; margin-left: auto; margin-right: auto; }
  .rooms {
    display: grid;
    grid-template-columns: 1fr 1fr;
    column-gap: 22px;
  }
  .bld.open .rooms { display: grid; }
  .room:nth-last-child(2):nth-child(odd),
  .room:nth-last-child(1):nth-child(even) { border-bottom: 0; }
}