:root {
  --red: #D52B1E; --red-soft: #FDECEA; --green: #1A7F4B; --green-soft: #E6F4EC;
  --blue: #0B5CAD; --blue-soft: #EEF5FC;
  --ink: #1C1C1E; --ink-2: #5B5B60; --ink-3: #8E8E93; --line: #E5E5EA;
  --bg: #F5F5F7; --card: #FFFFFF; --shadow: 0 1px 8px rgba(0,0,0,.05);
}
@media (prefers-color-scheme: dark) {
  :root {
    --red: #FF5A4E; --red-soft: #3A1E1C; --green: #3CC27A; --green-soft: #17301F;
    --blue: #5AA4F0; --blue-soft: #16273A;
    --ink: #F2F2F7; --ink-2: #C7C7CC; --ink-3: #8E8E93; --line: #38383A;
    --bg: #111113; --card: #1C1C1E; --shadow: none;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; background: var(--bg); color: var(--ink); }
body { font: 16px/1.55 -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif; -webkit-font-smoothing: antialiased; }
a { color: var(--blue); text-decoration: none; }
button { font: inherit; color: inherit; cursor: pointer; }
.container { max-width: 760px; margin: 0 auto; padding: 16px 16px 64px; }
.en { color: var(--ink-3); font-size: .85em; font-weight: 400; }
.muted { color: var(--ink-2); font-size: .9em; }
.row { display: flex; align-items: center; gap: 12px; }
.between { justify-content: space-between; }
.grow { flex: 1; min-width: 0; }
.center { text-align: center; }
.empty { text-align: center; padding: 80px 0; color: var(--ink-3); }

/* 顶栏 */
.bar { position: sticky; top: 0; z-index: 5; display: flex; align-items: center; gap: 12px; padding: 10px 16px;
  background: var(--red); color: #fff; }
.bar a { color: #fff; }
.brand { font-weight: 700; font-size: 18px; }
.brand span { font-weight: 500; opacity: .85; font-size: 15px; }
.back { font-size: 28px; line-height: 1; padding: 0 6px; }
.bar-title { flex: 1; font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lang { display: flex; background: rgba(255,255,255,.18); border-radius: 999px; padding: 3px; }
.lang button { border: 0; background: none; color: #fff; font-size: 12px; padding: 4px 10px; border-radius: 999px; }
.lang .on { background: #fff; color: var(--red); }

.hero { text-align: center; padding: 28px 8px 8px; }
.hero h1 { margin: 0; font-size: 34px; color: var(--red); }
.hero h1 span { font-size: 22px; font-weight: 500; }
.hero p { margin: 6px 0 0; color: var(--ink-2); }
.group { margin: 24px 4px 10px; font-size: 15px; color: var(--ink-2); }

.card { display: block; background: var(--card); border-radius: 16px; padding: 18px; margin-bottom: 14px; box-shadow: var(--shadow); color: inherit; border: 0; width: 100%; text-align: left; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 0 14px; }
@media (max-width: 400px) { .grid { grid-template-columns: 1fr; } }
.exam .icon { width: 48px; height: 48px; border-radius: 12px; display: grid; place-items: center; font-size: 26px; flex-shrink: 0; }
.exam .arrow { color: var(--ink-3); font-size: 24px; }
.exam .meta { margin-top: 12px; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.exam:hover { transform: translateY(-1px); }
.h2 { font-size: 17px; font-weight: 600; }
.title { font-size: 21px; font-weight: 700; }
.tag { display: inline-block; font-size: 12px; padding: 2px 9px; border-radius: 999px; margin-right: 6px; }
.tag.gray { background: var(--line); color: var(--ink-2); }
.tag.red { background: var(--red-soft); color: var(--red); }
.tag.green { background: var(--green-soft); color: var(--green); }
.promo { border: 2px solid var(--red); background: var(--red-soft); margin-top: 18px; }
.price { font-size: 24px; font-weight: 800; color: var(--red); white-space: nowrap; }
footer { text-align: center; color: var(--ink-3); font-size: 13px; margin-top: 30px; line-height: 2; }

.big-icon { font-size: 40px; }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); text-align: center; margin-top: 14px; }
.stats b { display: block; font-size: 20px; }
.stats span { font-size: 12px; color: var(--ink-3); }
.lockbar { background: var(--red-soft); display: flex; }
.tiles { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-bottom: 14px; }
.tile { background: var(--card); border-radius: 16px; padding: 18px; color: var(--ink); font-weight: 600; box-shadow: var(--shadow); }
.tile span:first-child { display: block; font-size: 26px; margin-bottom: 4px; }
.chapter { display: flex; align-items: center; padding: 12px 0; border-bottom: 1px solid var(--line); color: var(--ink); }
.chapter:last-child { border-bottom: 0; }
.source a { word-break: break-all; font-size: 13px; }

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; flex-wrap: wrap; min-height: 48px; padding: 10px 18px;
  border-radius: 12px; border: 0; background: var(--red); color: #fff; font-weight: 600; text-align: center; }
.btn .en { color: rgba(255,255,255,.8); }
.btn.ghost { background: var(--card); color: var(--red); border: 1.5px solid var(--red); }
.btn.ghost .en { color: var(--red); opacity: .7; }
.btn[disabled] { opacity: .45; cursor: default; }
.btn.small { min-height: 40px; padding: 8px 14px; }
.btn.wide { display: flex; width: 100%; margin-top: 12px; }
.nav { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 14px; }
.nav.three { grid-template-columns: 1fr 1fr 1fr; }
.scorebar { margin-bottom: 10px; display: flex; gap: 6px; align-items: center; }
.timer { color: var(--red); font-weight: 700; }

/* 题目 */
.stem { margin: 14px 0 16px; }
.stem .zh { font-size: 19px; font-weight: 600; line-height: 1.5; }
.en-sub { display: block; color: var(--ink-2); font-size: 14px; margin-top: 3px; }
.stem .en-sub { font-size: 15px; }
.opt { display: flex; align-items: flex-start; gap: 12px; width: 100%; text-align: left; padding: 13px; margin-bottom: 10px;
  background: var(--card); border: 1.5px solid var(--line); border-radius: 12px; }
.opt .zh { display: block; }
.opt:not([disabled]):hover { border-color: var(--blue); }
.letter { flex-shrink: 0; width: 26px; height: 26px; border-radius: 50%; background: var(--line); display: grid; place-items: center; font-size: 13px; font-weight: 700; }
.opt.sel { border-color: var(--blue); background: var(--blue-soft); } .opt.sel .letter { background: var(--blue); color: #fff; }
.opt.ok { border-color: var(--green); background: var(--green-soft); } .opt.ok .letter { background: var(--green); color: #fff; }
.opt.bad { border-color: var(--red); background: var(--red-soft); } .opt.bad .letter { background: var(--red); color: #fff; }
.opt[disabled] { cursor: default; color: var(--ink); }
.explain { border-top: 1px dashed var(--line); margin-top: 6px; padding-top: 12px; font-size: 15px; }
.verdict { font-weight: 700; margin-bottom: 8px; }
.v-ok { color: var(--green); } .v-bad { color: var(--red); }
.label { font-size: 12px; color: var(--ink-3); margin: 6px 0 2px; }
.src { margin-top: 12px; background: var(--bg); border-radius: 10px; padding: 10px 12px; font-size: 14px; }
.src summary { cursor: pointer; color: var(--ink-2); }
.src blockquote { margin: 8px 0; font-style: italic; color: var(--ink-2); }
.src a { word-break: break-all; font-size: 12px; }

.sheet { background: var(--card); border-radius: 16px; padding: 16px; margin-top: 14px; box-shadow: var(--shadow); }
.cells { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 10px; }
.cell { width: 42px; height: 42px; border-radius: 10px; border: 0; background: var(--line); }
.cell.done { background: var(--blue-soft); color: var(--blue); }
.cell.cur { outline: 2px solid var(--red); }

.result { text-align: center; padding: 32px 16px; }
.result.ok { background: var(--green-soft); } .result.bad { background: var(--red-soft); }
.result .verdict { font-size: 24px; }
.result.ok .verdict { color: var(--green); } .result.bad .verdict { color: var(--red); }
.score { font-size: 64px; font-weight: 800; } .score small { font-size: 24px; color: var(--ink-3); }
.finish { text-align: center; display: grid; gap: 12px; padding: 32px 18px; }
.finish .big { font-size: 56px; }

.perks ul { list-style: none; padding: 0; margin: 10px 0 0; }
.perks li { margin: 8px 0; }
.perks li .en { display: block; margin-left: 26px; }
.plan { display: flex; align-items: center; gap: 12px; position: relative; border: 2px solid transparent; cursor: pointer; }
.plan.on { border-color: var(--red); }
.badge { position: absolute; top: -10px; right: 14px; background: var(--red); color: #fff; font-size: 11px; padding: 2px 10px; border-radius: 999px; }
.fine { font-size: 12px; color: var(--ink-3); margin-top: 16px; }
.form { display: flex; gap: 10px; margin-top: 12px; flex-wrap: wrap; }
.form input { flex: 1; min-width: 200px; min-height: 48px; padding: 0 14px; border-radius: 12px; border: 1.5px solid var(--line); background: var(--card); color: var(--ink); font: inherit; }
.prose h2 { font-size: 18px; margin: 0 0 8px; }
.prose p { margin: 8px 0; }
.toast { position: fixed; left: 50%; bottom: 40px; transform: translateX(-50%); background: rgba(0,0,0,.85); color: #fff; padding: 10px 18px; border-radius: 10px; z-index: 50; max-width: 90vw; }

/* 政策页面与全站页脚 */
.legal h1 { font-size: 24px; margin: 0 0 4px; }
.legal h2 { font-size: 18px; margin: 22px 0 6px; }
.legal li { margin: 8px 0; }
.legal li .en { display: block; }
.en-p { color: var(--ink-2); font-size: 14px; }
.site-footer { text-align: center; color: var(--ink-3); font-size: 13px; padding: 8px 16px 32px; line-height: 2; }
.site-footer a { color: var(--ink-2); }
.static-intro ul { padding-left: 20px; }