:root{--ink:#17273a;--muted:#66778b;--blue:#185fa5;--blue2:#e9f3fc;--green:#14755b;--green2:#e8f6f0;--gold:#a86108;--gold2:#fff4d8;--red:#b42318;--line:#dce5ee;--paper:#f5f7fa;--panel:#fff;--shadow:0 16px 45px rgba(23,39,58,.08)}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;line-height:1.65}a{color:inherit}button,input,select,textarea{font:inherit}button,a{min-height:44px}button{cursor:pointer}button:disabled{cursor:not-allowed;opacity:.48}.top{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.96);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}.top-inner{max-width:1240px;margin:auto;padding:12px 24px;display:flex;align-items:center;gap:12px}.brand{margin-right:auto;font-weight:850;letter-spacing:-.02em}.brand small{display:block;color:var(--muted);font-size:11px;font-weight:600;letter-spacing:.08em}.nav-link,.btn{border:1px solid var(--line);border-radius:11px;background:#fff;padding:8px 14px;text-decoration:none;display:inline-flex;align-items:center;justify-content:center;gap:7px;font-weight:700;color:var(--ink)}.nav-link:hover,.btn:hover{border-color:#aabccf;background:#f9fbfd}.btn.primary{background:var(--blue);border-color:var(--blue);color:#fff}.btn.green{background:var(--green);border-color:var(--green);color:#fff}.btn.soft{background:var(--blue2);border-color:#c9e0f3;color:#14558f}.btn.danger{color:var(--red)}.btn.small{min-height:36px;padding:5px 10px;font-size:12px;border-radius:9px}.wrap{max-width:1240px;margin:auto;padding:34px 24px 70px}.hero{display:grid;grid-template-columns:1fr auto;gap:28px;align-items:end;margin-bottom:26px}.eyebrow{font-size:12px;font-weight:850;color:var(--blue);letter-spacing:.13em;text-transform:uppercase}.hero h1{font-size:clamp(32px,5vw,52px);line-height:1.12;letter-spacing:-.045em;margin:8px 0 12px}.hero p{max-width:760px;color:var(--muted);margin:0}.hero-stat{text-align:right;padding:18px 22px;border:1px solid var(--line);border-radius:16px;background:#fff;min-width:165px}.hero-stat b{font-size:28px;display:block}.hero-stat span{font-size:12px;color:var(--muted)}.notice{border:1px solid #ead39d;background:var(--gold2);color:#6f480e;padding:13px 16px;border-radius:13px;font-size:13px;margin:18px 0}.notice strong{color:#513003}.tabs,.chips{display:flex;gap:8px;flex-wrap:wrap}.tabs{padding:5px;background:#e8edf3;border-radius:14px;width:max-content;max-width:100%;margin:22px 0}.tab{border:0;background:transparent;padding:8px 18px;border-radius:10px;font-weight:750;color:var(--muted)}.tab.active{background:#fff;color:var(--blue);box-shadow:0 2px 10px rgba(23,39,58,.08)}.book-bar{display:flex;align-items:center;justify-content:space-between;gap:18px;margin:20px 0}.book-chip{border:1px solid var(--line);background:#fff;padding:8px 14px;border-radius:999px;font-weight:700}.book-chip.active{background:var(--ink);border-color:var(--ink);color:#fff}.progress-summary{display:flex;align-items:center;gap:14px;margin:20px 0 24px;padding:16px 18px;background:#fff;border:1px solid var(--line);border-radius:15px}.bar{height:9px;background:#e9eef3;border-radius:999px;overflow:hidden;flex:1}.bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--blue),#43a4df);border-radius:inherit;transition:width .3s}.progress-summary b{white-space:nowrap}.lesson-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.lesson-card{position:relative;background:#fff;border:1px solid var(--line);border-radius:17px;padding:20px;display:flex;flex-direction:column;min-height:225px;box-shadow:0 3px 14px rgba(23,39,58,.025);transition:transform .18s,border-color .18s}.lesson-card:hover{transform:translateY(-2px);border-color:#b5c9db}.lesson-no{font-size:11px;font-weight:850;color:var(--blue);letter-spacing:.09em;text-transform:uppercase}.lesson-card h2{font-size:20px;line-height:1.28;margin:8px 0 4px;letter-spacing:-.02em}.lesson-card h3{font-size:13px;color:var(--muted);font-weight:600;margin:0 0 12px}.lesson-meta{display:flex;gap:10px;flex-wrap:wrap;color:var(--muted);font-size:11px;margin-bottom:14px}.lesson-card .bar{margin: auto 0 12px}.card-foot{display:flex;align-items:center;justify-content:space-between;gap:10px}.card-foot span{font-size:12px;color:var(--muted)}.empty,.loading,.error{padding:42px 22px;text-align:center;background:#fff;border:1px solid var(--line);border-radius:17px;color:var(--muted)}.error{color:var(--red);border-color:#f0c4bf;background:#fff8f7}.private-pill{display:inline-flex;align-items:center;border-radius:999px;padding:4px 9px;background:#edf1f5;color:#4b5e73;font-size:11px;font-weight:750}.lesson-head{background:linear-gradient(135deg,#152d48,#1e5f8d);color:#fff;border-radius:22px;padding:30px;margin-bottom:20px;box-shadow:var(--shadow)}.lesson-head .eyebrow{color:#a9d8f7}.lesson-head h1{font-size:clamp(28px,4vw,43px);line-height:1.2;margin:8px 0 5px;letter-spacing:-.035em}.lesson-head p{margin:0;color:#d9e9f5}.lesson-actions{display:flex;gap:9px;flex-wrap:wrap;margin-top:20px}.lesson-actions .btn{background:rgba(255,255,255,.12);border-color:rgba(255,255,255,.28);color:#fff}.lesson-actions .btn.primary{background:#fff;border-color:#fff;color:#174f7b}.toolbar{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin:14px 0 20px}.toolbar label{font-size:12px;color:var(--muted);font-weight:700}.toolbar select{border:1px solid var(--line);border-radius:9px;padding:7px 10px;background:#fff;color:var(--ink)}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 285px;gap:20px;align-items:start}.panel{background:#fff;border:1px solid var(--line);border-radius:18px;padding:22px}.panel h2{margin:0 0 5px;font-size:23px;letter-spacing:-.025em}.panel-intro{color:var(--muted);font-size:13px;margin:0 0 20px}.side{display:grid;gap:14px;position:sticky;top:85px}.side .panel{padding:18px}.side h3{margin:0 0 9px;font-size:15px}.side p,.side li{font-size:12px;color:var(--muted)}.side ol{padding-left:19px;margin:8px 0}.vocab-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:13px}.vocab-card{border:1px solid var(--line);border-radius:14px;padding:17px;background:#fff}.vocab-card.known{border-color:#94cdb9;background:#f7fcfa}.word-line{display:flex;align-items:baseline;gap:8px;flex-wrap:wrap}.word-line h3{font-size:23px;margin:0;letter-spacing:-.02em}.phonetic{color:var(--blue);font-size:13px}.pos{color:var(--muted);font-size:12px}.zh{font-weight:700;margin:5px 0}.usage{font-size:12px;color:var(--muted);min-height:38px}.example{border-left:3px solid #c7dfef;padding-left:10px;margin:12px 0;font-size:13px}.example span{display:block;color:var(--muted);font-size:12px;margin-top:3px}.card-actions{display:flex;gap:7px;flex-wrap:wrap}.sentence-list{display:grid;gap:13px}.sentence-card{border:1px solid var(--line);border-radius:14px;padding:18px}.sentence-card.mastered{border-color:#94cdb9;background:#f7fcfa}.sentence-top{display:flex;gap:12px;align-items:flex-start}.sentence-no{flex:0 0 29px;height:29px;border-radius:50%;display:grid;place-items:center;background:var(--blue2);color:var(--blue);font-size:11px;font-weight:800}.sentence-en{font-size:20px;line-height:1.45;font-weight:700;letter-spacing:-.012em}.sentence-zh{color:var(--muted);font-size:13px;margin:7px 0}.sentence-note{font-size:12px;color:#526c83;background:#f2f6fa;padding:8px 10px;border-radius:9px;margin:10px 0}.reading-title{font-size:26px;margin:0 0 12px}.reading-text{font-size:20px;line-height:1.9}.reading-sentence{display:inline;border-radius:5px;padding:2px 0;cursor:pointer;transition:background .15s}.reading-sentence:hover{background:#e6f2fb}.reading-zh{color:var(--muted);border-top:1px solid var(--line);padding-top:16px;margin-top:20px}.import-box{margin-top:24px;border-top:1px dashed #bdccd9;padding-top:20px}.import-box summary{cursor:pointer;font-weight:800;color:var(--blue);min-height:44px}.import-box textarea{width:100%;min-height:180px;resize:vertical;border:1px solid var(--line);border-radius:12px;padding:13px;margin:12px 0;line-height:1.7}.import-box input[type=file]{display:block;margin:10px 0;max-width:100%}.objectives{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin-bottom:20px}.objective{background:var(--blue2);border-radius:12px;padding:13px;font-size:13px}.analysis-block{padding:18px 0;border-top:1px solid var(--line)}.analysis-block:first-child{border-top:0;padding-top:0}.analysis-block h3{margin:0 0 8px}.analysis-block p{color:#44576b}.grammar-example{background:#f3f7fb;padding:11px 13px;border-radius:10px;font-weight:650}.quiz-card{border:1px solid var(--line);border-radius:15px;padding:20px;margin-bottom:14px}.quiz-card h3{font-size:17px;margin:0 0 14px}.options{display:grid;gap:8px}.option{text-align:left;border:1px solid var(--line);background:#fff;border-radius:10px;padding:11px 13px}.option:hover{background:#f5f9fc}.option.correct{border-color:#65ae92;background:var(--green2);color:#0e634a}.option.wrong{border-color:#dda29b;background:#fff1ef;color:var(--red)}.feedback{font-size:13px;margin-top:11px;padding:10px 12px;border-radius:9px;background:#f3f6f9}.toast{position:fixed;left:50%;bottom:28px;transform:translate(-50%,15px);background:#14273a;color:#fff;padding:10px 16px;border-radius:11px;box-shadow:var(--shadow);opacity:0;pointer-events:none;transition:.2s;z-index:100;max-width:min(90vw,620px);text-align:center;font-size:13px}.toast.show{opacity:1;transform:translate(-50%,0)}.footer{max-width:1240px;margin:auto;padding:22px 24px 38px;color:var(--muted);font-size:11px;display:flex;gap:16px;flex-wrap:wrap;border-top:1px solid var(--line)}.hidden{display:none!important}:focus-visible{outline:3px solid #77b9e9;outline-offset:2px}
/* v3.636：大字标题并排 + 小字分课时（对齐 BEC 分级栏） */
.level-bar{margin:22px 0 4px}
.level-title-row{display:flex;gap:10px;flex-wrap:wrap}
.level-title{border:1px solid var(--line);background:#fff;border-radius:15px;padding:13px 18px;text-align:left;cursor:pointer;display:flex;flex-direction:column;gap:2px;transition:border-color .15s,box-shadow .15s}
.level-title:hover{border-color:#b5c9db}
.level-title.active{border-color:var(--blue);box-shadow:0 6px 18px rgba(24,95,165,.12)}
.lt-main{font-size:19px;font-weight:850;letter-spacing:-.02em;color:var(--ink)}
.lt-sub{font-size:11px;color:var(--muted);font-weight:600}
.level-title.active .lt-main{color:var(--blue)}
.lesson-chip-row{display:flex;flex-wrap:wrap;gap:5px;margin-top:12px;padding:9px 11px;background:#eef2f6;border-radius:12px}
.lesson-chip{border:1px solid var(--line);background:#fff;padding:4px 11px;border-radius:999px;font-size:12px;font-weight:700;color:var(--muted);min-height:34px;cursor:pointer;transition:.12s}
.lesson-chip:hover{border-color:#aabccf;color:var(--ink)}
.lesson-chip.active{background:var(--blue);border-color:var(--blue);color:#fff}
@media(max-width:680px){.level-title{padding:11px 14px}.lt-main{font-size:17px}.lesson-chip{font-size:11px;padding:4px 9px}}
/* v3.637：生词学习卡（对标 BEC 中级：翻卡动画 + 词义插图 + 音节拆分 + 反义/近义 + 拼写单词） */
.nc-flash{display:flex;flex-direction:column;align-items:center;gap:14px}
.nc-count{font-size:12px;color:var(--muted);font-weight:700}
.nc-card{position:relative;width:100%;max-width:560px;height:340px;cursor:pointer;transform-style:preserve-3d;transition:transform .45s}
.nc-card.flipped{transform:rotateY(180deg)}
.nc-card.nc-in{animation:ncSpring .42s cubic-bezier(.18,.89,.32,1.28)}
@keyframes ncSpring{0%{opacity:0;transform:scale(.86) translateY(10px)}100%{opacity:1;transform:scale(1) translateY(0)}}
.nc-face{position:absolute;inset:0;background:#fff;border:1px solid var(--line);border-radius:20px;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;backface-visibility:hidden;padding:26px 30px;box-shadow:0 12px 34px rgba(23,39,58,.09)}
.nc-front{background:linear-gradient(135deg,#f7fbff,#eef5fc)}
.nc-back{transform:rotateY(180deg);justify-content:flex-start;gap:6px;overflow-y:auto;align-items:stretch;text-align:left}
.nc-emo{font-size:44px;line-height:1;margin-bottom:6px;display:inline-block}
.nc-emo-glyph{display:inline-block}
.nc-emo.nc-pop .nc-emo-glyph{animation:ncPop .5s cubic-bezier(.18,.89,.32,1.4)}
@keyframes ncPop{0%{transform:scale(0) rotate(-12deg)}70%{transform:scale(1.25) rotate(4deg)}100%{transform:scale(1) rotate(0)}}
.nc-word{font-size:36px;font-weight:850;letter-spacing:-.02em;color:var(--ink)}
.nc-word-sm{font-size:24px;font-weight:850;letter-spacing:-.02em;color:var(--ink);text-align:center}
.nc-syl{display:flex;flex-wrap:wrap;justify-content:center;gap:2px;margin-top:8px;font-size:24px;font-weight:800;letter-spacing:.02em}
.nc-syl span{display:inline-block}
.nc-syl-gap{width:8px}
.nc-syl-plain{color:#888}
.nc-ph{font-size:14px;color:var(--blue);margin-top:6px}
.nc-exsmall{font-size:13px;color:#526c83;margin-top:10px;line-height:1.5;max-width:440px}
.nc-zh{font-size:24px;font-weight:800;color:var(--ink);margin-top:4px;text-align:center}
.nc-ee{font-size:13px;color:#5b6f85;font-style:italic;text-align:center}
.nc-root{font-size:12.5px;color:#8a5a12;background:#fff8e6;padding:7px 11px;border-radius:9px;line-height:1.5}
.nc-ex{font-size:15px;color:#34475c;margin-top:6px;line-height:1.55;cursor:pointer}
.nc-ex:hover{color:var(--blue)}
.nc-excn{font-size:13px;color:var(--muted)}
.nc-usage{font-size:12px;color:#526c83;background:#f2f6fa;padding:8px 11px;border-radius:9px}
.nc-rel{display:flex;flex-wrap:wrap;align-items:center;gap:6px;margin-top:6px}
.nc-rel-label{font-size:12px;font-weight:850;flex-shrink:0}
.nc-rel-chip{display:inline-flex;align-items:center;gap:5px;border:1px solid var(--line);background:#fff;border-radius:999px;padding:4px 11px;font-size:13px;font-weight:700;cursor:pointer;min-height:32px;transition:.12s}
.nc-rel-chip:hover{border-color:#aabccf;background:#f9fbfd}
.nc-rel-speak{font-size:12px;opacity:.7}
.nc-rel-speak:hover{opacity:1}
.nc-controls{display:flex;gap:9px;flex-wrap:wrap;justify-content:center;margin-top:6px}
.nc-done{padding:26px;text-align:center;color:var(--green);font-weight:700}
/* 拼写单词游戏 */
.nc-overlay{position:fixed;inset:0;background:rgba(23,39,58,.5);display:flex;align-items:center;justify-content:center;z-index:100;padding:20px;backdrop-filter:blur(4px)}
.nc-spell{position:relative;background:#fff;border-radius:20px;padding:28px;max-width:460px;width:100%;box-shadow:0 20px 60px rgba(23,39,58,.28);display:flex;flex-direction:column;gap:14px}
.nc-spell-close{position:absolute;top:14px;right:14px;border:none;background:#f2f6fa;width:36px;height:36px;border-radius:50%;font-size:16px;cursor:pointer;color:var(--muted)}
.nc-spell-close:hover{background:#e6edf4}
.nc-spell-title{font-size:20px;font-weight:850;letter-spacing:-.02em}
.nc-spell-hint{font-size:14px;color:var(--muted)}
.nc-spell-target{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;min-height:52px;padding:10px;background:#f7faff;border:2px dashed var(--line);border-radius:12px}
.nc-slot{width:38px;height:44px;border-bottom:3px solid var(--blue);display:inline-flex;align-items:center;justify-content:center;font-size:26px;font-weight:850;color:var(--ink);text-transform:uppercase}
.nc-slot.filled{animation:ncSlotIn .2s ease}
@keyframes ncSlotIn{0%{transform:scale(.4)}100%{transform:scale(1)}}
.nc-spell-target.correct{border-color:var(--green);background:#e8f6f0}
.nc-spell-target.wrong{border-color:var(--red);background:#fdf0ee;animation:ncShake .3s}
@keyframes ncShake{0%,100%{transform:translateX(0)}25%{transform:translateX(-5px)}75%{transform:translateX(5px)}}
.nc-spell-letters{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}
.nc-letter{width:46px;height:46px;border:1px solid var(--line);background:#fff;border-radius:11px;font-size:22px;font-weight:850;cursor:pointer;text-transform:uppercase;color:var(--ink);transition:.12s}
.nc-letter:hover{border-color:var(--blue);background:#e9f3fc;transform:translateY(-2px)}
.nc-spell-actions{display:flex;gap:8px;justify-content:center;flex-wrap:wrap}
.nc-spell-actions .btn{min-height:38px;font-size:13px}
@media(max-width:680px){.nc-card{height:300px}.nc-word{font-size:29px}.nc-zh{font-size:22px}.nc-word-sm{font-size:20px}.nc-syl{font-size:20px}.nc-exsmall{max-width:100%}.nc-slot{width:32px;height:38px;font-size:22px}.nc-letter{width:40px;height:40px;font-size:20px}}@media(max-width:980px){.lesson-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.workspace{grid-template-columns:1fr}.side{position:static;grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:680px){.top-inner,.wrap,.footer{padding-left:15px;padding-right:15px}.top-inner{gap:7px}.brand{font-size:13px}.brand small{display:none}.nav-link{padding:7px 10px;font-size:12px}.wrap{padding-top:22px}.hero{grid-template-columns:1fr}.hero-stat{text-align:left}.book-bar{align-items:flex-start;flex-direction:column}.lesson-grid,.vocab-grid,.objectives{grid-template-columns:1fr}.lesson-head{padding:22px 18px}.panel{padding:17px}.sentence-en,.reading-text{font-size:18px}.side{grid-template-columns:1fr}.progress-summary{flex-wrap:wrap}.progress-summary .bar{flex-basis:100%;order:3}.lesson-actions{display:grid;grid-template-columns:repeat(2,minmax(0,1fr))}.lesson-actions .btn{width:100%;padding:8px 6px}.tabs{width:100%;display:grid;grid-template-columns:repeat(5,minmax(0,1fr));overflow:visible;gap:3px}.tab{white-space:nowrap;padding:8px 3px;font-size:11px}.hero h1{font-size:35px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}