:root {
  --bg: #F6F7F8;
  --surface: #FFFFFF;
  --ink: #1B2430;
  --muted: #66707C;
  --accent: #0E7C72;
  --accent-ink: #0A5F58;
  --accent-weak: rgba(14, 124, 114, 0.09);
  --good: #17804C;
  --good-bg: rgba(23, 128, 76, 0.08);
  --warn: #9A6B1F;
  --warn-bg: rgba(154, 107, 31, 0.10);
  --bad: #B8433A;
  --bad-bg: rgba(184, 67, 58, 0.07);
  --border: #E3E7EA;
  --code-bg: #EDF0F2;
  --shadow: 0 1px 3px rgba(27, 36, 48, 0.06);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12161B;
    --surface: #1A2027;
    --ink: #E6EAEE;
    --muted: #93A0AB;
    --accent: #3FB9AC;
    --accent-ink: #5ECABE;
    --accent-weak: rgba(63, 185, 172, 0.11);
    --good: #4CC38A;
    --good-bg: rgba(76, 195, 138, 0.10);
    --warn: #D9A85C;
    --warn-bg: rgba(217, 168, 92, 0.12);
    --bad: #F08B83;
    --bad-bg: rgba(229, 115, 106, 0.12);
    --border: #2A323B;
    --code-bg: #232B33;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  }
}
/* Android 平台强调色 */
body[data-platform="android"] {
  --accent: #2E8B57;
  --accent-ink: #1F6B41;
  --accent-weak: rgba(46, 139, 87, 0.10);
}
@media (prefers-color-scheme: dark) {
  body[data-platform="android"] {
    --accent: #5BC98A;
    --accent-ink: #7AD6A2;
    --accent-weak: rgba(91, 201, 138, 0.12);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 15.5px;
  line-height: 1.7;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
button { font-family: inherit; cursor: pointer; }
code {
  font-family: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.86em;
  background: var(--code-bg);
  padding: 1px 5px;
  border-radius: 4px;
}
pre {
  background: var(--code-bg);
  padding: 12px 14px;
  border-radius: 8px;
  overflow-x: auto;
  line-height: 1.55;
}
pre code { background: none; padding: 0; }

/* ---------- header ---------- */
.site-head {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 20;
}
.head-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.brand { display: flex; align-items: baseline; gap: 10px; }
.brand-mark {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 22px;
  font-weight: 800;
  color: var(--accent);
  letter-spacing: 0.02em;
}
.brand-sub { font-size: 13px; color: var(--muted); }

.platform-tabs {
  display: flex;
  gap: 4px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 3px;
}
.ptab {
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
  padding: 6px 22px;
  border-radius: 7px;
  transition: background 0.15s, color 0.15s;
}
.ptab.on { background: var(--accent); color: #fff; }
.ptab:not(.on):hover { color: var(--ink); }
.head-link {
  color: var(--accent);
  text-decoration: none;
  font-size: 13.5px;
  font-weight: 650;
  white-space: nowrap;
}
.head-link:hover { text-decoration: underline; }

/* ---------- subnav ---------- */
.subnav { background: var(--surface); border-bottom: 1px solid var(--border); }
.subnav-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  gap: 4px;
}
.vtab {
  border: none;
  background: none;
  color: var(--muted);
  font-size: 14.5px;
  font-weight: 600;
  padding: 12px 16px 10px;
  border-bottom: 2.5px solid transparent;
  margin-bottom: -1px;
}
.vtab.on { color: var(--accent); border-bottom-color: var(--accent); }
.vtab:not(.on):hover { color: var(--ink); }

/* ---------- main ---------- */
.main { flex: 1; max-width: 960px; width: 100%; margin: 0 auto; padding: 28px 20px 60px; }
.view h2 { margin: 0 0 6px; font-size: 22px; }
.hint { color: var(--muted); font-size: 13.5px; margin: 0; max-width: 40em; }
.hint strong { color: var(--accent); }

/* ---------- checkin ---------- */
.checkin-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 18px;
}
.streak-box {
  display: flex;
  gap: 10px;
  flex-shrink: 0;
}
.streak-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  box-shadow: var(--shadow);
}
.streak-num {
  font-size: 24px;
  font-weight: 800;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  line-height: 1.2;
}
.streak-label { font-size: 12px; color: var(--muted); }

.progress-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}
.progress-track {
  flex: 1;
  height: 8px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  width: 0;
  background: var(--accent);
  border-radius: 99px;
  transition: width 0.3s ease;
}
.progress-text {
  font-size: 13.5px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.btn {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--ink);
  border-radius: 8px;
  padding: 6px 14px;
  font-size: 13.5px;
  font-weight: 600;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn.ghost { background: transparent; }

.done-banner {
  background: var(--good-bg);
  color: var(--good);
  font-weight: 650;
  padding: 12px 18px;
  border-radius: 10px;
  margin-bottom: 18px;
}

/* ---------- question cards ---------- */
.q-list { display: flex; flex-direction: column; gap: 14px; }
.qcard {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  overflow: hidden;
}
.qcard.done { opacity: 0.75; }
.qcard-head {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 16px 18px 0;
}
.qcard-idx {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  color: var(--accent);
  font-weight: 700;
  font-size: 14px;
  padding-top: 2px;
  flex-shrink: 0;
  font-variant-numeric: tabular-nums;
}
.qcard-title { font-size: 15.5px; font-weight: 650; line-height: 1.55; flex: 1; margin: 0; }
.qcard-meta {
  display: flex;
  gap: 6px;
  align-items: center;
  padding: 8px 18px 0 44px;
  flex-wrap: wrap;
}
.badge {
  font-size: 11.5px;
  font-weight: 700;
  border-radius: 99px;
  padding: 1px 9px;
}
.badge.basic { background: var(--good-bg); color: var(--good); }
.badge.advanced { background: var(--warn-bg); color: var(--warn); }
.badge.topic { background: var(--accent-weak); color: var(--accent-ink); font-weight: 600; }

.qcard details { margin: 10px 18px 0 44px; }
.qcard summary {
  cursor: pointer;
  color: var(--accent);
  font-size: 13.5px;
  font-weight: 650;
  user-select: none;
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 5px;
}
.qcard summary::-webkit-details-marker { display: none; }
.qcard summary::before { content: "▸"; transition: transform 0.15s; }
.qcard details[open] summary::before { transform: rotate(90deg); }
.answer {
  margin-top: 8px;
  padding: 14px 16px;
  background: var(--accent-weak);
  border-radius: 8px;
  font-size: 14.5px;
}
.answer p { margin: 0 0 8px; }
.answer p:last-child { margin-bottom: 0; }
.answer ul, .answer ol { margin: 4px 0 8px; padding-left: 1.4em; }
.answer li { margin-bottom: 4px; }
.qcard-foot {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 18px 14px 44px;
}
.master-check {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 13.5px;
  color: var(--muted);
  cursor: pointer;
  user-select: none;
}
.master-check input {
  width: 17px;
  height: 17px;
  accent-color: var(--accent);
  cursor: pointer;
}
.qcard.done .master-check { color: var(--good); font-weight: 650; }
.qcard-src { font-size: 12px; color: var(--muted); }

/* ---------- browse ---------- */
.browse-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 18px;
}
.seg {
  display: flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 2px;
}
.seg button {
  border: none;
  background: none;
  color: var(--muted);
  font-size: 13.5px;
  font-weight: 600;
  padding: 5px 14px;
  border-radius: 6px;
}
.seg button.on { background: var(--accent); color: #fff; }
#topic-filter, #search-input {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--ink);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 13.5px;
  font-family: inherit;
}
#search-input { flex: 1; min-width: 140px; }
.browse-count { font-size: 13px; color: var(--muted); white-space: nowrap; }

/* ---------- manual ---------- */
.manual-view { padding: 0; max-width: none; }
#manual-frame {
  width: 100%;
  height: calc(100vh - 110px);
  border: none;
  display: block;
  background: var(--bg);
}
/* manual 视图占满宽度 */
.main:has(#view-manual:not([hidden])) { max-width: none; padding: 0; }

/* ---------- footer ---------- */
.site-foot {
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 12.5px;
  text-align: center;
  padding: 18px 20px;
}
.site-foot a { color: var(--accent); text-decoration: none; }

@media (max-width: 560px) {
  .head-inner { padding: 10px 14px; }
  .brand-sub { display: none; }
  .main { padding: 20px 14px 48px; }
  .qcard-meta, .qcard details, .qcard-foot { padding-left: 18px; }
}