:root {
  --bg: #f5f3ee;
  --card: #ffffff;
  --ink: #1d2433;
  --muted: #667085;
  --line: #e4e0d6;
  --brand: #1f3a5f;
  --brand-2: #2f5d8f;
  --accent: #f6c453;
  --ok: #2e8b57;
  --bad: #c2453d;
  --focus: #2f5d8f33;
  --lv-a1: #9ec5e8; --lv-a2: #5fa8d3;
  --lv-b1: #7cc59a; --lv-b2: #3f9e6b;
  --lv-c1: #f2b45a; --lv-c2: #e07b39;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(16,24,40,.05), 0 4px 16px rgba(16,24,40,.06);
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, "Songti SC", serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12161d; --card: #1b212b; --ink: #e8ebf0; --muted: #98a2b3; --line: #2c3442;
    --brand: #8fb4e3; --brand-2: #a9c6ec; --focus: #8fb4e333;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.25);
    color-scheme: dark;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg); color: var(--ink);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}
a { color: var(--brand-2); }
button { font: inherit; }
.topbar {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
  padding: 10px max(16px, env(safe-area-inset-left)); padding-top: max(10px, env(safe-area-inset-top));
  background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); font-weight: 650; }
.logo { display: inline-grid; place-items: center; width: 32px; height: 32px; border-radius: 9px; background: #1f3a5f; color: var(--accent); font-family: Georgia, serif; font-weight: 700; font-size: 15px; }
#nav { display: flex; align-items: center; gap: 4px; font-size: 14px; }
#nav a, #nav button { color: var(--muted); text-decoration: none; padding: 6px 10px; border-radius: 8px; background: none; border: 0; cursor: pointer; }
#nav a:hover, #nav button:hover { background: var(--card); color: var(--ink); }
#nav .who { color: var(--ink); font-weight: 550; }

main { max-width: 920px; margin: 0 auto; padding: 24px 16px 80px; }
.loading { color: var(--muted); padding: 60px 0; text-align: center; }
h1 { font-size: 28px; line-height: 1.25; margin: 0 0 8px; letter-spacing: -.01em; }
h2 { font-size: 20px; margin: 0 0 12px; }
h3 { font-size: 16px; margin: 0 0 8px; }
p { margin: 0 0 12px; }
.muted { color: var(--muted); }
.small { font-size: 14px; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); padding: 22px; margin-bottom: 18px; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
@media (max-width: 720px) { .grid2 { grid-template-columns: 1fr; } }
.row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; }
.spacer { flex: 1; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 11px 20px; border-radius: 11px; border: 1px solid transparent;
  background: var(--brand); color: #fff; font-weight: 600; cursor: pointer; text-decoration: none;
  transition: transform .05s ease, background .15s;
}
@media (prefers-color-scheme: dark) { .btn { color: #0f1520; } }
.btn:hover { background: var(--brand-2); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn.ghost:hover { background: var(--bg); }
.btn.big { padding: 14px 28px; font-size: 17px; }
.btn.link { background: none; color: var(--muted); padding: 8px 10px; font-weight: 500; }

/* forms */
.auth { max-width: 400px; margin: 4vh auto 0; }
.tabs { display: flex; background: var(--bg); border-radius: 10px; padding: 4px; margin-bottom: 18px; }
.tabs button { flex: 1; padding: 8px; border: 0; border-radius: 8px; background: none; color: var(--muted); cursor: pointer; font-weight: 550; }
.tabs button.on { background: var(--card); color: var(--ink); box-shadow: var(--shadow); }
label.f { display: block; margin-bottom: 14px; font-size: 14px; color: var(--muted); }
label.f input {
  display: block; width: 100%; margin-top: 6px; padding: 11px 12px; font: inherit; color: var(--ink);
  background: var(--bg); border: 1px solid var(--line); border-radius: 10px; outline: none;
}
label.f input:focus { border-color: var(--brand-2); box-shadow: 0 0 0 3px var(--focus); }
.err { color: var(--bad); font-size: 14px; min-height: 20px; margin-bottom: 8px; }

/* hero */
.hero { padding: 28px; background: linear-gradient(135deg, #1f3a5f, #2f5d8f); color: #fff; border: 0; }
.hero p { color: #dbe6f3; }
.hero .btn { background: var(--accent); color: #1d2433; }
.hero .btn:hover { background: #ffd57a; }
.hero .btn.ghost { background: transparent; color: #fff; border-color: #ffffff55; }
.facts { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin: 18px 0 20px; }
.facts div { background: #ffffff14; border-radius: 10px; padding: 10px 12px; font-size: 13px; color: #dbe6f3; }
.facts b { display: block; color: #fff; font-size: 15px; }
@media (max-width: 600px) { .facts { grid-template-columns: 1fr 1fr; } }

/* level badge */
.lv { display: inline-grid; place-items: center; min-width: 46px; height: 30px; padding: 0 9px; border-radius: 8px; font-weight: 700; font-size: 15px; color: #1d2433; background: var(--line); }
.lv.big { min-width: 104px; height: 82px; font-size: 40px; border-radius: 18px; letter-spacing: -.02em; }
.lv-A1 { background: var(--lv-a1); } .lv-A2 { background: var(--lv-a2); }
.lv-B1 { background: var(--lv-b1); } .lv-B2 { background: var(--lv-b2); color: #fff; }
.lv-C1 { background: var(--lv-c1); } .lv-C2 { background: var(--lv-c2); color: #fff; }
.lv-Pre-A1 { background: #d0d5dd; }

/* history */
.hist { list-style: none; padding: 0; margin: 0; }
.hist li { display: flex; align-items: center; gap: 14px; padding: 12px 0; border-top: 1px solid var(--line); }
.hist li:first-child { border-top: 0; }
.hist .when { color: var(--muted); font-size: 14px; }
.hist .secs { display: flex; gap: 6px; flex-wrap: wrap; font-size: 13px; color: var(--muted); }

/* self-level picker */
.picker { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 10px; margin: 14px 0 20px; }
.picker button {
  text-align: left; padding: 12px 14px; border-radius: 12px; border: 1.5px solid var(--line); background: var(--card);
  color: var(--ink); cursor: pointer; line-height: 1.45;
}
.picker button:hover { border-color: var(--brand-2); }
.picker button.on { border-color: var(--brand); box-shadow: 0 0 0 3px var(--focus); }
.picker small { display: block; color: var(--muted); font-size: 13px; }

/* test */
.tbar { position: sticky; top: 53px; z-index: 5; background: var(--bg); padding: 8px 0 12px; margin-bottom: 8px; }
.steps { display: flex; gap: 6px; margin-bottom: 8px; }
.steps div { flex: 1; font-size: 13px; color: var(--muted); }
.steps .track { height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; margin-top: 4px; }
.steps .fill { height: 100%; background: var(--brand-2); transition: width .3s ease; }
.steps .cur { color: var(--ink); font-weight: 600; }
.qhead { font-size: 13px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin-bottom: 10px; }
.stem { font-family: var(--serif); font-size: 21px; line-height: 1.5; margin: 6px 0 18px; }
.stem .gap { display: inline-block; min-width: 72px; border-bottom: 2px solid var(--brand-2); margin: 0 4px; }
.opts { display: grid; gap: 10px; }
.opt {
  display: flex; align-items: flex-start; gap: 12px; width: 100%; text-align: left; padding: 12px 14px;
  border: 1.5px solid var(--line); background: var(--card); color: var(--ink); border-radius: 12px; cursor: pointer;
  font-family: var(--serif); font-size: 17px; line-height: 1.45;
}
.opt:hover { border-color: var(--brand-2); }
.opt .k { flex: none; display: inline-grid; place-items: center; width: 26px; height: 26px; border-radius: 7px; background: var(--bg); font: 600 13px/1 -apple-system, sans-serif; color: var(--muted); margin-top: 1px; }
.opt.on { border-color: var(--brand); background: color-mix(in srgb, var(--brand) 8%, var(--card)); }
.opt.on .k { background: var(--brand); color: #fff; }
.opt.idk { font-family: inherit; font-size: 14px; color: var(--muted); border-style: dashed; padding: 9px 14px; }
.qblock { margin-bottom: 26px; }
.qblock .q { font-weight: 600; margin-bottom: 10px; }
.passage { font-family: var(--serif); font-size: 17.5px; line-height: 1.75; }
.passage h3 { font-family: inherit; font-size: 20px; }
.passage p { margin-bottom: 14px; }
.split { display: grid; grid-template-columns: 1.15fr 1fr; gap: 22px; align-items: start; }
.split .passage-col { position: sticky; top: 140px; max-height: calc(100vh - 160px); overflow: auto; }
@media (max-width: 820px) { .split { grid-template-columns: 1fr; } .split .passage-col { position: static; max-height: none; } }
.player { display: flex; align-items: center; gap: 16px; padding: 18px; border-radius: 14px; background: var(--bg); margin-bottom: 22px; }
.play { width: 60px; height: 60px; border-radius: 50%; border: 0; background: var(--brand); color: #fff; cursor: pointer; display: grid; place-items: center; flex: none; }
.play:disabled { opacity: .4; cursor: not-allowed; }
.play svg { width: 26px; height: 26px; }
.play.playing { animation: pulse 1.2s ease-in-out infinite; }
@keyframes pulse { 50% { box-shadow: 0 0 0 10px var(--focus); } }
.next-row { display: flex; justify-content: flex-end; gap: 10px; margin-top: 8px; position: sticky; bottom: 0; padding: 14px 0 max(14px, env(safe-area-inset-bottom)); background: linear-gradient(transparent, var(--bg) 30%); }

/* result */
.res-top { display: flex; gap: 22px; align-items: center; flex-wrap: wrap; }
.res-top .meta { flex: 1; min-width: 220px; }
.scale { margin: 22px 0 6px; }
.scale .bands { display: flex; height: 10px; border-radius: 5px; overflow: hidden; }
.scale .bands div { height: 100%; }
.scale .labels { position: relative; height: 18px; font-size: 12px; color: var(--muted); }
.scale .labels span { position: absolute; transform: translateX(-50%); top: 2px; }
.scale .rows { margin-top: 10px; }
.scale .r { display: grid; grid-template-columns: 54px 1fr 96px; align-items: center; gap: 10px; height: 34px; font-size: 14px; }
.scale .lane { position: relative; height: 100%; }
.scale .lane::before { content: ""; position: absolute; left: 0; right: 0; top: 50%; border-top: 1px dashed var(--line); }
.scale .dot { position: absolute; top: 50%; width: 14px; height: 14px; margin: -7px 0 0 -7px; border-radius: 50%; background: var(--brand); border: 2px solid var(--card); box-shadow: 0 0 0 1px var(--brand); }
.scale .ci { position: absolute; top: 50%; height: 4px; margin-top: -2px; background: color-mix(in srgb, var(--brand) 30%, transparent); border-radius: 2px; }
.scale .r.total .dot { width: 18px; height: 18px; margin: -9px 0 0 -9px; background: var(--accent); box-shadow: 0 0 0 1px #b8892a; }
.scale .val { text-align: right; color: var(--muted); }
.cando { margin: 0; padding-left: 20px; }
.cando li { margin-bottom: 6px; }
table.eq { width: 100%; border-collapse: collapse; font-size: 14px; }
table.eq th, table.eq td { text-align: left; padding: 8px 6px; border-top: 1px solid var(--line); }
table.eq th { color: var(--muted); font-weight: 550; border-top: 0; }
table.eq tr.me td { background: color-mix(in srgb, var(--accent) 22%, transparent); font-weight: 600; }
.note { font-size: 13px; color: var(--muted); }

/* review */
.rv { border-top: 1px solid var(--line); padding: 14px 0; }
.rv:first-child { border-top: 0; }
.rv .q { font-family: var(--serif); font-size: 17px; margin: 4px 0 8px; }
.rv ol { margin: 0 0 6px; padding-left: 22px; font-family: var(--serif); }
.rv li.ans { color: var(--ok); font-weight: 600; }
.rv li.wrong { color: var(--bad); text-decoration: line-through; }
.rv .ex { font-size: 14px; color: var(--muted); background: var(--bg); padding: 8px 10px; border-radius: 8px; }
.tag { display: inline-block; font-size: 12px; padding: 2px 8px; border-radius: 6px; background: var(--bg); color: var(--muted); margin-right: 6px; }
.tag.ok { background: #2e8b5722; color: var(--ok); }
.tag.bad { background: #c2453d22; color: var(--bad); }
details.ctx summary { cursor: pointer; color: var(--brand-2); font-size: 14px; margin-bottom: 6px; }
details.ctx .passage { font-size: 15px; background: var(--bg); padding: 12px; border-radius: 10px; }
.filter { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 8px; }
.filter button { border: 1px solid var(--line); background: var(--card); color: var(--muted); border-radius: 999px; padding: 4px 12px; cursor: pointer; font-size: 14px; }
.filter button.on { background: var(--brand); border-color: var(--brand); color: #fff; }

.toast { position: fixed; left: 50%; bottom: 28px; transform: translateX(-50%); background: #1d2433; color: #fff; padding: 10px 18px; border-radius: 10px; font-size: 14px; z-index: 50; box-shadow: var(--shadow); max-width: calc(100vw - 32px); }