:root {
  --bg: #111; --fg: #eee; --muted: #aaa; --line: #6a6a6a; --box: #1b1b1b;
  --good: #6fd38a; --bad: #ff8a80; --accent: #8ab4ff; --t1: #ffd166; --t2: #6fd38a; --t3: #8ab4ff; --t4: #ff8a80;
  color-scheme: dark;
}
* { box-sizing: border-box; }
body { background: var(--bg); color: var(--fg); font: 18px/1.5 system-ui, sans-serif; margin: 0 auto; max-width: 760px; padding: 0 16px 48px; }
a { color: var(--accent); }
header { padding: 14px 0; border-bottom: 1px solid var(--line); margin-bottom: 8px; display: flex; gap: 10px; align-items: baseline; }
.brand { font-weight: 700; font-size: 1.2em; text-decoration: none; color: var(--fg); }
.skip { position: absolute; left: -999px; } .skip:focus { left: 16px; top: 8px; background: #000; padding: 6px; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
h1 { font-size: 1.5em; margin: 16px 0 8px; } h2 { font-size: 1.2em; margin: 20px 0 8px; }
h1:focus, main:focus { outline: none; }
.box { border: 1px solid var(--line); border-radius: 8px; padding: 12px 16px; margin: 12px 0; background: var(--box); }
button, select { font: inherit; color: var(--fg); background: #262626; border: 1px solid var(--line); border-radius: 8px; padding: 10px 14px; margin: 4px 6px 4px 0; cursor: pointer; min-height: 44px; }
button:hover { background: #333; } button:focus-visible, select:focus-visible, a:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
button.main { background: #1f3a66; border-color: var(--accent); font-weight: 600; }
button.rec { background: #5c1f1f; border-color: var(--bad); }
button[disabled] { opacity: .5; cursor: default; }
ul.lessons { list-style: none; padding: 0; margin: 0; }
ul.lessons li { margin: 8px 0; }
ul.lessons h3 { margin: 4px 0; font-size: 1.1em; }
ul.lessons p { margin: 4px 0; }
.talk-line { border-left: 4px solid var(--line); padding: 6px 12px; margin: 10px 0; }
.talk-line.A { border-color: var(--t1); } .talk-line.B { border-color: var(--t3); }
.talk-line.now { background: #222; }
.talk-line .who { font-weight: 600; } .talk-line .zh { font-size: 1.5em; }
ul.lessons a { display: inline-block; padding: 6px 2px; font-size: 1.05em; }
.prog { color: var(--muted); font-size: .9em; }
.card { text-align: center; }
.hz { font-size: 4.2em; line-height: 1.2; margin: 6px 0; }
.py { font-size: 1.6em; } .num { color: var(--muted); } .en { font-size: 1.15em; margin-top: 4px; }
.t1 { color: var(--t1); } .t2 { color: var(--t2); } .t3 { color: var(--t3); } .t4 { color: var(--t4); } .t5 { color: var(--muted); }
.note { color: var(--muted); font-size: .95em; }
.row { display: flex; flex-wrap: wrap; justify-content: center; }
.result { min-height: 3em; }
.result .ok { color: var(--good); } .result .no { color: var(--bad); }
.result ul { margin: 6px 0; padding-left: 22px; text-align: left; }
canvas { width: 100%; height: 160px; display: block; margin-top: 8px; background: #0b0b0b; border: 1px solid #333; border-radius: 6px; }
.meter { height: 8px; background: #222; border-radius: 4px; overflow: hidden; margin: 8px auto; max-width: 300px; }
.meter i { display: block; height: 100%; width: 0; background: var(--good); transition: width .05s; }
.choices button { min-width: 120px; }
label { display: inline-block; margin: 6px 12px 6px 0; }
.small { font-size: .9em; color: var(--muted); }