/* 英语小课堂 · 不用外部字体和 CDN；手机 390px 优先，iPad 横屏上课 */
:root {
  --bg: #eef4f8; --panel: #ffffff; --ink: #1c2a35; --muted: #5a6b78; --line: #d2dfe8;
  --accent: #f4b400; --accent-ink: #2a1f00; --good: #2c9558; --good-bg: #e3f4ea; --bad: #cf4436; --bad-bg: #fbe7e4;
  --board: #2d5743; --board-deep: #244736; --chalk: #f4f6ef; --chalk-dim: #bfcfc4; --chalk-y: #f6d870;
  --wood: #a8693a; --wood-dark: #7d4a25;
  --f-ui: -apple-system, "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", system-ui, sans-serif;
  --f-kid: ui-rounded, "SF Pro Rounded", "Arial Rounded MT Bold", "PingFang SC", "Noto Sans SC", system-ui, sans-serif;
  --r: 16px;
}
@media (prefers-color-scheme: dark) {
  body.page { --bg: #121a21; --panel: #1b2630; --ink: #e3ecf1; --muted: #9cafbc; --line: #2c3c48;
    --good-bg: #173726; --bad-bg: #3d1d19; color-scheme: dark; }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.55 var(--f-ui); }
a { color: inherit; }
h1 { font-size: 1.45rem; line-height: 1.3; margin: 0 0 8px; text-wrap: balance; }
h2 { font-size: 1.05rem; margin: 0 0 10px; }
.muted { color: var(--muted); }
.small { font-size: .86rem; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
[hidden] { display: none !important; }

/* 页头页脚 */
.top { background: var(--panel); border-bottom: 1px solid var(--line);
  padding-left: max(16px, env(safe-area-inset-left)); padding-right: max(16px, env(safe-area-inset-right)); }
.top-in { max-width: 960px; margin: 0 auto; display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 6px 16px; min-height: 52px; }
.brand { font-weight: 700; text-decoration: none; font-size: 1.05rem; }
.nav { display: flex; gap: 14px; flex-wrap: wrap; }
.nav a { text-decoration: none; color: var(--muted); }
.wrap { max-width: 960px; margin: 0 auto; padding: 18px max(16px, env(safe-area-inset-right)) 28px max(16px, env(safe-area-inset-left)); display: grid; gap: 16px; }
.beian { text-align: center; font-size: .8rem; color: var(--muted); padding: 8px 16px 18px; display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.beian a { color: var(--muted); }

/* 通用 */
.card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--r); padding: 16px; min-width: 0; }
.narrow { max-width: 420px; width: 100%; margin: 24px auto; }
.flash { background: var(--good-bg); border-radius: 12px; padding: 10px 14px; }
.error { color: var(--bad); }
.warn { background: var(--bad-bg); border-radius: 12px; padding: 10px 14px; margin: 0; }
.form { display: grid; gap: 8px; }
.form label { font-weight: 600; font-size: .95rem; margin-top: 4px; }
input:not([type=checkbox]), textarea { width: 100%; font: inherit; color: inherit; background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 10px 12px; }
textarea { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: .9rem; line-height: 1.5; }
.btn { display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: 0 18px; border-radius: 999px; border: 2px solid var(--line); background: var(--panel); color: var(--ink); font: 600 1rem var(--f-ui); text-decoration: none; cursor: pointer; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.danger { border-color: var(--bad); color: var(--bad); }
.btn:disabled { opacity: .45; cursor: default; }
.btn.big { min-height: 60px; font-size: 1.25rem; padding: 0 40px; }
.actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 6px; }
.pill { display: inline-block; font-size: .78rem; font-weight: 600; padding: 2px 10px; border-radius: 999px; background: var(--bg); border: 1px solid var(--line); color: var(--muted); vertical-align: middle; }
.pill.s-finished { background: var(--good-bg); border-color: transparent; color: var(--good); }
.pill.s-active { background: #fff4cc; border-color: transparent; color: #7a5a00; }
.pill.s-failed { background: var(--bad-bg); border-color: transparent; color: var(--bad); }
.kv { display: grid; grid-template-columns: max-content 1fr; gap: 6px 14px; margin: 0 0 12px; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; min-width: 0; overflow-wrap: anywhere; }
.danger-zone { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.ov-opt { display: flex; gap: 8px; align-items: center; font-weight: 400 !important; }
.ov-opt input { width: 20px; height: 20px; }

/* 列表 */
.list { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.row { display: grid; gap: 2px; padding: 12px 14px; background: var(--panel); border: 1px solid var(--line); border-radius: 14px; text-decoration: none; }
.row-main { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.row-sub { color: var(--muted); font-size: .88rem; overflow-wrap: anywhere; }
.chips { list-style: none; margin: 0 0 8px; padding: 0; display: flex; flex-wrap: wrap; gap: 6px; }
.chips li { padding: 4px 12px; border-radius: 999px; font-weight: 600; }
.chips .yes { background: var(--good-bg); color: var(--good); }
.chips .no { background: var(--bg); color: var(--muted); border: 1px dashed var(--line); }
.talk { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.talk li { padding: 8px 12px; border-radius: 12px; max-width: 88%; overflow-wrap: anywhere; text-align: left; justify-self: start; }
.talk .who { display: block; font-size: .75rem; color: var(--muted); font-weight: 600; }
.talk .teacher { background: var(--panel); border: 1px solid var(--line); }
.talk .child { background: #fff4cc; color: #2a2100; justify-self: end; }
.talk .child .who { color: #7a5a00; }
.talk .cue { justify-self: center; color: var(--muted); font-size: .85rem; background: none; }

/* 首页 */
.hello h1 { font-size: 1.6rem; }
.hello { display: grid; gap: 6px; }
.unit-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 12px; }
.unit-card { display: grid; gap: 2px; align-content: start; background: var(--panel); border: 2px solid var(--line); border-radius: 20px; padding: 14px; text-decoration: none; min-width: 0; }
.unit-card:hover { border-color: var(--accent); }
.unit-icon { font-size: 2.6rem; line-height: 1.1; }
.unit-no { font-size: .78rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.unit-en { font: 700 1.15rem var(--f-kid); }
.unit-zh { color: var(--muted); }
.unit-meta { font-size: .8rem; color: var(--muted); margin-top: 6px; }

/* 试课 */
.segs-bar { display: flex; flex-wrap: wrap; gap: 6px; }
.seg-btn { border: 1px solid var(--line); background: var(--panel); color: var(--ink); border-radius: 999px; padding: 6px 12px; font: inherit; cursor: pointer; }
.say { display: flex; gap: 8px; position: sticky; bottom: 0; background: var(--bg); padding-block: 8px; }
.say input { flex: 1; min-width: 0; }

/* ================= 上课页 ================= */
body.classroom { --bg: #fdf6e6; --ink: #22303b; background: var(--bg); color: var(--ink); min-height: 100vh; display: flex; flex-direction: column; }
.c-top { display: flex; align-items: center; gap: 12px; background: #fff; border-bottom: 1px solid #efe2c2;
  padding: 8px max(16px, env(safe-area-inset-right)) 8px max(16px, env(safe-area-inset-left)); }
.c-back { text-decoration: none; font-weight: 600; color: var(--muted); white-space: nowrap; }
.c-title { flex: 1; min-width: 0; font: 600 1.05rem var(--f-kid); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.c-title span { color: var(--muted); font-weight: 400; margin-left: 4px; }
.c-timer { font: 600 1rem var(--f-kid); font-variant-numeric: tabular-nums; background: #fff4cc; color: #6b4e00; border-radius: 999px; padding: 4px 12px; white-space: nowrap; }
.c-main { flex: 1; width: 100%; max-width: 1180px; margin: 0 auto; padding: 12px max(16px, env(safe-area-inset-right)) 20px max(16px, env(safe-area-inset-left)); display: grid; gap: 14px; align-content: start; }
.c-segs { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 6px; min-height: 30px; }
.c-segs li { padding: 4px 12px; border-radius: 999px; background: #fff; border: 1px solid #efe2c2; color: var(--muted); font-size: .9rem; }
.c-segs li.on { background: var(--board); border-color: var(--board); color: var(--chalk); }
.c-segs li.done { color: var(--ink); }

.c-stage { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.25fr); gap: 14px; align-items: stretch; }
@media (max-width: 760px) { .c-stage { grid-template-columns: 1fr; } }

.teacher { background: #fff; border: 1px solid #efe2c2; border-radius: 24px; padding: 18px; display: grid; justify-items: center; align-content: start; gap: 8px; text-align: center; min-width: 0; }
.t-avatar { position: relative; width: clamp(120px, 24vw, 190px); aspect-ratio: 1; max-width: 100%; }
.t-avatar img { width: 100%; height: 100%; display: block; border-radius: 50%; background: #ffe8a8; }
.t-ring { position: absolute; inset: -7px; border-radius: 50%; border: 6px solid transparent; }
.teacher[data-state="listening"] .t-ring { border-color: #7fd4a0; }
.teacher[data-state="thinking"] .t-ring { border-color: #f6d870; border-style: dashed; animation: spin 3s linear infinite; }
.teacher[data-state="speaking"] .t-ring { border-color: var(--accent); animation: pulse .9s ease-in-out infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes pulse { 50% { transform: scale(1.06); } }
.t-name { font: 700 1.2rem var(--f-kid); }
.t-name span { display: block; font: 400 .92rem var(--f-ui); color: var(--muted); }
.t-sub { margin: 0; font: 600 clamp(1.2rem, 2.6vw, 1.6rem)/1.35 var(--f-kid); min-height: 1.4em; overflow-wrap: anywhere; text-wrap: balance; }
.t-sub-zh { margin: 0; font-size: clamp(1rem, 2.1vw, 1.25rem); line-height: 1.45; color: var(--muted); min-height: 1.45em; overflow-wrap: anywhere; text-wrap: balance; }

.board { position: relative; border: 12px solid var(--wood); border-radius: 18px; background: radial-gradient(ellipse at 20% 15%, rgba(255,255,255,.07), transparent 55%), linear-gradient(160deg, var(--board), var(--board-deep));
  color: var(--chalk); display: grid; justify-items: center; align-content: center; gap: 6px; padding: 18px 16px 52px; min-height: clamp(260px, 42vh, 420px); text-align: center; min-width: 0; box-shadow: 0 6px 0 rgba(0,0,0,.08); }
.board.pop { animation: pop .4s ease; }
@keyframes pop { from { transform: scale(.97); } to { transform: none; } }
.card-pic { font-size: clamp(4.5rem, 13vw, 8rem); line-height: 1.05; min-height: 1.05em; }
.card-pic img { width: clamp(100px, 18vw, 160px); height: auto; filter: invert(.96) sepia(.1); }
.card-word { font: 700 clamp(2.2rem, 6.5vw, 4rem)/1.1 var(--f-kid); overflow-wrap: anywhere; }
.card-zh { font-size: clamp(1.05rem, 2.6vw, 1.4rem); color: var(--chalk-dim); }
.kid-sub { position: absolute; left: 14px; right: 14px; bottom: 10px; margin: 0; font-size: 1rem; color: var(--chalk-y); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

.cam-box { grid-column: 1 / -1; justify-self: end; width: min(260px, 100%); position: relative; }
.cam-view { width: 100%; aspect-ratio: 4 / 3; border-radius: 16px; overflow: hidden; background: #222; }
.cam-view video { width: 100%; height: 100%; object-fit: cover; }
.cam-label { position: absolute; left: 8px; bottom: 8px; font-size: .78rem; color: #fff; background: rgba(0,0,0,.45); border-radius: 999px; padding: 2px 8px; }

.stars { background: #fff; border: 1px solid #efe2c2; border-radius: 20px; padding: 12px 14px; display: grid; gap: 8px; }
.stars-head { font-size: .92rem; color: var(--muted); }
.stars-head b { color: #6b4e00; font-size: 1.05rem; }
.star-list { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(92px, 1fr)); gap: 8px; }
.star-list li { display: grid; justify-items: center; gap: 2px; padding: 8px 4px; border-radius: 14px; background: #f6f1e4; filter: grayscale(1); opacity: .55; transition: opacity .3s, filter .3s; }
.star-list li.lit { filter: none; opacity: 1; background: #fff4cc; box-shadow: inset 0 0 0 2px var(--accent); }
.star-list li.boom { animation: boom .6s ease; }
@keyframes boom { 40% { transform: scale(1.18) rotate(-4deg); } }
.s-pic { font-size: 1.9rem; line-height: 1.1; }
.star-list img { width: 34px; height: 34px; }
.s-word { font: 600 .95rem var(--f-kid); text-align: center; overflow-wrap: anywhere; }

.c-controls { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; }
.c-controls .btn.on { background: var(--bad-bg); }
.parent-bar { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; justify-content: center; padding-top: 4px; border-top: 1px dashed #efe2c2; }
.pb-label { font-size: .82rem; font-weight: 700; color: var(--muted); letter-spacing: .06em; }
.pb-btn { border: 1px solid #e6d7b0; background: #fff; border-radius: 999px; padding: 6px 12px; font: inherit; font-size: .9rem; color: var(--ink); cursor: pointer; }
.pb-btn.sent { background: #fff4cc; }
.pb-lat { font-size: .82rem; color: var(--muted); font-variant-numeric: tabular-nums; min-width: 8em; text-align: center; }
select { width: 100%; font: inherit; color: inherit; background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 10px 12px; }

.overlay { position: fixed; inset: 0; background: rgba(30, 40, 50, .45); display: grid; place-items: center; z-index: 20;
  padding: max(16px, env(safe-area-inset-top)) max(16px, env(safe-area-inset-right)) max(16px, env(safe-area-inset-bottom)) max(16px, env(safe-area-inset-left)); }
.ov-card { background: #fff; border-radius: 28px; padding: 26px 22px; width: min(460px, 100%); display: grid; gap: 10px; justify-items: center; text-align: center; max-height: 100%; overflow: auto; }
.ov-card p { margin: 0; }
.ov-pic { font-size: 4rem; line-height: 1; }
.ov-msg { min-height: 1.5em; color: var(--bad); font-weight: 600; }
.ov-actions { display: flex; gap: 10px; flex-wrap: wrap; justify-content: center; }
.end-words { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 6px; justify-content: center; }
.end-words li { background: #fff4cc; border-radius: 999px; padding: 4px 12px; font: 600 1rem var(--f-kid); }

@media (prefers-reduced-motion: reduce) { * { animation: none !important; transition: none !important; } }