:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --surface-2: #f0f2f5;
  --text: #1f2328;
  --muted: #656d76;
  --border: #d8dee4;
  --accent: #0f766e;
  --accent-soft: #d5efec;
  --accent-text: #ffffff;
  --ok: #1a7f37;
  --ok-soft: #dafbe1;
  --bad: #cf222e;
  --bad-soft: #ffebe9;
  --warn: #9a6700;
  --mark: #fff1b8;
  --shadow: 0 1px 2px rgba(31, 35, 40, .06), 0 4px 14px rgba(31, 35, 40, .06);
  --radius: 12px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1419;
    --surface: #171d24;
    --surface-2: #1f2730;
    --text: #e6edf3;
    --muted: #8d96a0;
    --border: #2d3743;
    --accent: #2dd4bf;
    --accent-soft: #123a37;
    --accent-text: #04201d;
    --ok: #3fb950;
    --ok-soft: #12301b;
    --bad: #f85149;
    --bad-soft: #3a1618;
    --warn: #d29922;
    --mark: #4a3b0a;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 4px 14px rgba(0, 0, 0, .25);
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.6 "Segoe UI", "Microsoft JhengHei", "PingFang TC", system-ui, sans-serif;
}
h1, h2, h3, h4 { margin: 0; line-height: 1.3; }
h2 { font-size: 1.15rem; margin-bottom: 12px; }
a { color: var(--accent); }
kbd {
  font: 11px/1 ui-monospace, Consolas, monospace;
  padding: 2px 5px;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--surface-2);
  color: var(--muted);
}
mark { background: var(--mark); color: inherit; padding: 0 2px; border-radius: 3px; }

/* ---------- controls ---------- */
button {
  font: inherit;
  cursor: pointer;
  padding: 7px 14px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  transition: background .12s, border-color .12s;
}
button:hover:not(:disabled) { background: var(--surface-2); }
button:disabled { opacity: .5; cursor: not-allowed; }
button:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}
button.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-text); font-weight: 600; }
button.primary:hover:not(:disabled) { filter: brightness(1.08); background: var(--accent); }
button.primary kbd { background: transparent; color: inherit; border-color: currentColor; opacity: .7; }
button.ghost { background: transparent; border-color: transparent; color: var(--muted); }
button.ghost:hover:not(:disabled) { background: var(--surface-2); color: var(--text); }
button.danger { color: var(--bad); border-color: var(--bad); background: transparent; }
button.small { padding: 3px 10px; font-size: 13px; }
button.icon { padding: 2px 6px; border: none; background: transparent; font-size: 15px; line-height: 1; border-radius: 6px; }
button.icon:hover { background: var(--surface-2); }

input, select, textarea {
  font: inherit;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 10px;
}
textarea { width: 100%; resize: vertical; }

.row { display: flex; gap: 8px; align-items: center; margin-top: 12px; }
.row.wrap { flex-wrap: wrap; }
.row.center, .center { justify-content: center; text-align: center; }
.hint { color: var(--muted); font-size: 13.5px; margin: 8px 0 0; }
.hint.warn { color: var(--warn); }
.muted { color: var(--muted); }
.phon { color: var(--muted); font-family: "Segoe UI", "Lucida Sans Unicode", sans-serif; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px 20px;
  margin-bottom: 14px;
}

/* ---------- layout ---------- */
.top {
  max-width: 880px;
  margin: 0 auto;
  padding: 22px 16px 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand h1 { font-size: 1.35rem; }
.stats { display: flex; gap: 8px; }
.stats > div {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 6px 14px;
  text-align: center;
  min-width: 72px;
}
.stats b { display: block; font-size: 1.3rem; line-height: 1.2; font-variant-numeric: tabular-nums; }
.stats span { font-size: 12px; color: var(--muted); }

.tabs {
  max-width: 880px;
  margin: 0 auto;
  padding: 0 16px;
  display: flex;
  gap: 4px;
  border-bottom: 1px solid var(--border);
  overflow-x: auto;
}
.tabs button {
  border: none;
  border-bottom: 2px solid transparent;
  border-radius: 0;
  background: transparent;
  color: var(--muted);
  padding: 10px 14px;
  white-space: nowrap;
}
.tabs button:hover { background: transparent; color: var(--text); }
.tabs button[aria-selected="true"] { color: var(--text); border-bottom-color: var(--accent); font-weight: 600; }

main { max-width: 880px; margin: 0 auto; padding: 18px 16px 60px; }

/* ---------- word list ---------- */
.toolbar { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }
.toolbar input[type="search"] { flex: 1 1 220px; }
.manual { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.manual input[name="sentence"] { grid-column: 1 / -1; }
.manual button { grid-column: 1 / -1; justify-self: start; }

.word { padding: 14px 18px; }
.w-head { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.w-head h3 { font-size: 1.2rem; }
.pos { font-size: 12px; color: var(--accent); background: var(--accent-soft); padding: 1px 8px; border-radius: 99px; }
.spacer { flex: 1; }
.level { color: var(--accent); letter-spacing: 1px; font-size: 11px; }
.del { color: var(--muted); }
.word .zh { width: 100%; margin-top: 8px; border-color: transparent; background: var(--surface-2); }
.word .zh:hover, .word .zh:focus { border-color: var(--border); }
.def { margin: 8px 0 0; color: var(--muted); font-size: 14px; }
.ex { margin: 8px 0 0; font-size: 14.5px; border-left: 3px solid var(--border); padding-left: 10px; }
.empty { color: var(--muted); text-align: center; padding: 30px 0; }
.empty-state { text-align: center; padding: 32px 20px; }
.empty-state p { color: var(--muted); }

/* ---------- practice ---------- */
.setup .fields { display: flex; gap: 16px; flex-wrap: wrap; align-items: center; }
.fields label { display: flex; align-items: center; gap: 8px; }
.fields.col { flex-direction: column; align-items: stretch; }
.fields.col .row input { flex: 1; }
.setup [data-act="start"] { margin-top: 14px; }

.progress { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; color: var(--muted); font-size: 14px; font-variant-numeric: tabular-nums; }
.progress .bar { flex: 1; height: 6px; background: var(--surface-2); border-radius: 99px; overflow: hidden; }
.progress .bar span { display: block; height: 100%; background: var(--accent); border-radius: 99px; transition: width .25s; }
.progress .score { color: var(--ok); }

.qcard { padding: 26px 24px; }
.prompt { font-size: 2rem; font-weight: 700; text-align: center; }
.prompt.zh { font-size: 1.6rem; font-weight: 600; }
.big-say { font-size: 1.1rem; padding: 12px 24px; border-radius: 99px; background: var(--accent-soft); border-color: transparent; color: var(--text); }
.big-say:hover:not(:disabled) { background: var(--accent-soft); filter: brightness(.96); }

.options { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 22px; }
.opt { text-align: left; display: flex; gap: 10px; align-items: center; padding: 12px 14px; min-height: 54px; }
.opt.correct { background: var(--ok-soft) !important; border-color: var(--ok); opacity: 1; }
.opt.wrong { background: var(--bad-soft) !important; border-color: var(--bad); opacity: 1; }
.opt:disabled { cursor: default; }

.cloze-sent { font-size: 1.2rem; line-height: 2.1; margin: 0; }
.blank { font-size: 1.05rem; padding: 2px 8px; margin: 0 4px; border-width: 0 0 2px; border-radius: 4px 4px 0 0; background: var(--surface-2); }
.letters { font-family: ui-monospace, Consolas, monospace; letter-spacing: 1px; }
input.correct, textarea.correct { border-color: var(--ok); background: var(--ok-soft); }
input.wrong, textarea.wrong { border-color: var(--bad); background: var(--bad-soft); }
.dict-in { width: 100%; margin-top: 16px; font-size: 1.1rem; padding: 10px 12px; }

.feedback { margin-top: 18px; padding-top: 16px; border-top: 1px dashed var(--border); }
.fb-head { font-weight: 700; font-size: 1.05rem; }
.fb-head.ok { color: var(--ok); }
.fb-head.bad { color: var(--bad); }
.fb-word { margin-top: 8px; display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.fb-word b { font-size: 1.1rem; }
.feedback .next { margin-top: 14px; }
.yours { margin: 6px 0 0; color: var(--muted); }
.diff { font-size: 1.05rem; line-height: 1.9; margin: 8px 0 0; }
.d-ok { color: var(--ok); }
.d-miss { color: var(--bad); text-decoration: underline wavy; text-underline-offset: 3px; }
.d-extra { color: var(--muted); text-decoration: line-through; }
.answer { margin: 8px 0 0; font-weight: 600; }

.result { text-align: center; }
.big-score { font-size: 3rem; font-weight: 800; margin: 4px 0; color: var(--accent); }
.big-score small { font-size: 1.2rem; color: var(--muted); font-weight: 500; }
.result h3 { margin-top: 18px; font-size: 1rem; }
.wrong-list { list-style: none; padding: 0; margin: 10px auto 0; max-width: 480px; text-align: left; }
.wrong-list li { display: flex; gap: 10px; align-items: center; padding: 6px 0; border-bottom: 1px solid var(--border); }
.wrong-list span { color: var(--muted); }
.result .row { justify-content: center; flex-wrap: wrap; }

.switch { display: flex; gap: 8px; align-items: center; margin: 6px 0; cursor: pointer; }
#set-rate { padding: 0; flex: 1; max-width: 260px; }

/* ---------- web app additions ---------- */
body { padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left); -webkit-text-size-adjust: 100%; }
code { font-family: ui-monospace, Consolas, monospace; background: var(--surface-2); padding: 2px 6px; border-radius: 5px; word-break: break-all; }
.error { color: var(--bad); margin: 4px 0 0; }
h3.sub { font-size: .98rem; margin: 18px 0 6px; }
h3.sub:first-of-type { margin-top: 4px; }
.steps { margin: 6px 0; padding-left: 1.4em; }
.steps li { margin: 4px 0; }
.bookmarklet { display: inline-block; padding: 3px 10px; border-radius: 6px; background: var(--accent-soft); text-decoration: none; font-weight: 600; }
details summary { cursor: pointer; margin: 8px 0; color: var(--accent); }
details form { margin: 6px 0 4px; max-width: 360px; }
a.btn {
  display: inline-block; padding: 7px 14px; border-radius: 8px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text); text-decoration: none;
}
.fields.col label { flex-direction: column; align-items: stretch; gap: 4px; }
.fields.col label:has(input[type="range"]) { flex-direction: row; align-items: center; }

.toast {
  position: fixed; left: 50%; bottom: calc(20px + env(safe-area-inset-bottom)); transform: translateX(-50%);
  max-width: min(420px, calc(100vw - 32px)); padding: 10px 16px; border-radius: 10px; z-index: 10;
  background: var(--text); color: var(--bg); box-shadow: var(--shadow); font-size: 14px; white-space: pre-line;
}
.toast.err { background: var(--bad); color: #fff; }

.auth { min-height: 100vh; display: grid; place-items: center; padding: 16px; }
.auth-card { width: min(380px, 100%); }
.auth-card .brand { justify-content: center; margin-bottom: 16px; }
.auth-card form { display: flex; flex-direction: column; gap: 10px; }
.auth-card label { display: flex; flex-direction: column; gap: 4px; }
.seg { display: grid; grid-template-columns: 1fr 1fr; background: var(--surface-2); border-radius: 9px; padding: 3px; margin-bottom: 14px; }
.seg button { border: none; background: transparent; border-radius: 7px; }
.seg button[aria-selected="true"] { background: var(--surface); box-shadow: var(--shadow); font-weight: 600; }

.narrow { max-width: 560px; }
.add-page .brand { margin: 8px 0 14px; }
.add-page .brand h1 { font-size: 1.2rem; }
.add-page .fields.col { gap: 10px; }
.add-page .phon, .add-page .def { margin: 0; }
.add-page .row { flex-wrap: wrap; }
.picker .hint { margin-top: 0; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip { padding: 5px 10px; border-radius: 99px; font-size: 14px; }
.chip.on, .chip.on:hover:not(:disabled) { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }

/* Touch devices: larger targets, no keyboard hints */
@media (hover: none) {
  button, a.btn { min-height: 42px; }
  button.icon { min-width: 36px; min-height: 36px; font-size: 18px; }
  kbd, .desktop-only { display: none; }
  .opt { min-height: 60px; font-size: 1.05rem; }
  input, select, textarea { font-size: 16px; } /* prevents iOS zoom on focus */
}

@media (max-width: 560px) {
  .options { grid-template-columns: 1fr; }
  .manual { grid-template-columns: 1fr; }
  .prompt { font-size: 1.6rem; }
  .top { padding-top: 14px; }
  .stats { width: 100%; }
  .stats > div { flex: 1; min-width: 0; padding: 6px 8px; }
  .tabs { padding: 0 8px; }
  .tabs button { padding: 10px 10px; flex: 1; }
  .card { padding: 16px; }
  .qcard { padding: 20px 16px; }
}