:root{color-scheme:light dark;--bg:light-dark(#f3f7f3,#101713);--surface:light-dark(#fff,#19241d);--surface-soft:light-dark(#f4f8f4,#1e2b22);--text:light-dark(#192b20,#e6f3e9);--muted:light-dark(#65786b,#9eb5a6);--border:light-dark(#dae7dc,#35483b);--primary:light-dark(#266f4a,#8bd3a3);--primary-dark:light-dark(#175a36,#b7efcb);--tint:light-dark(#e7f4e9,#29402f);--gold:light-dark(#b67c25,#e3b868);--goldbg:light-dark(#fff7e9,#332c20);--red:light-dark(#aa4338,#ef9d93);--shadow:0 16px 52px #001d090b; font-family:system-ui,-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--text);font-size:15px;line-height:1.7}button,input,select{font:inherit}button{cursor:pointer}a{color:inherit;text-decoration:none}h1,h2,h3,p{margin-top:0}.app{min-height:100vh;background:var(--bg)}.wrap{width:min(1440px,calc(100% - 44px));margin:auto}.topbar{border-bottom:1px solid var(--border);background:var(--surface);position:relative;z-index:2}.top-inner{max-width:1440px;padding:12px 22px;margin:auto;display:flex;justify-content:space-between;align-items:center;gap:18px}.brand{display:flex;align-items:center;gap:11px;font-size:17px;font-weight:850;letter-spacing:-.02em}.brand small{display:block;font-size:9px;letter-spacing:.16em;font-weight:700;color:var(--muted);line-height:1.2}.brand-mark{height:40px;width:40px;display:grid;place-items:center;background:var(--primary);color:var(--surface);border-radius:12px;font-size:29px}.top-actions{display:flex;align-items:center;gap:22px;color:var(--muted);font-size:13px}.top-actions a:hover{color:var(--primary)}.hero{display:grid;grid-template-columns:minmax(0,1.4fr) minmax(270px,.6fr);gap:26px;padding:46px 0 32px;align-items:stretch}.eyebrow,.kicker{display:block;letter-spacing:.09em;text-transform:uppercase;font-size:11px;font-weight:850;color:var(--primary);margin-bottom:7px}.hero h1{font-size:clamp(34px,4.8vw,62px);letter-spacing:-.06em;line-height:1.13;margin:14px 0 16px}.hero h1 em{color:var(--primary);font-style:normal}.hero p{max-width:700px;color:var(--muted);line-height:1.85}.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin:23px 0 18px}.button{border:1px solid var(--border);padding:10px 15px;border-radius:11px;background:var(--surface);color:var(--text);display:inline-flex;align-items:center;justify-content:center;gap:5px;font-size:13px;font-weight:750;min-height:39px}.button.primary{background:var(--primary);border-color:var(--primary);color:light-dark(#fff,#102018)}.button.secondary:hover{border-color:var(--primary);color:var(--primary)}.subtle{font-size:12px!important;color:var(--muted);line-height:1.7!important}.hero-metrics{background:var(--surface);border:1px solid var(--border);border-radius:22px;padding:24px;box-shadow:var(--shadow)}.metric-label{display:flex;align-items:center;justify-content:space-between;gap:10px;font-size:13px;font-weight:800}.local-tag{border-radius:99px;padding:4px 10px;background:var(--tint);color:var(--primary);font-size:10px}.hero-number{display:flex;align-items:baseline;gap:9px;margin:14px 0}.hero-number strong{font-size:60px;letter-spacing:-.07em;line-height:1;font-weight:850}.hero-number span{font-size:13px;color:var(--muted)}.bar{height:9px;background:var(--surface-soft);border:1px solid var(--border);border-radius:20px;overflow:hidden}.bar span{display:block;width:0;height:100%;background:var(--primary);transition:width .4s}.metric-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:21px 0}.metric-grid>div{display:flex;flex-direction:column;border-radius:12px;background:var(--surface-soft);padding:12px}.metric-grid strong{font-size:24px;line-height:1.2}.metric-grid small{font-size:11px;color:var(--muted)}.layout{display:grid;grid-template-columns:258px minmax(0,1fr);align-items:start;gap:21px;padding-bottom:45px}.sidepanel{position:sticky;top:20px;max-height:calc(100vh - 40px);overflow:auto;background:var(--surface);border:1px solid var(--border);border-radius:18px;padding:18px}.side-heading h2{font-size:19px;line-height:1.3;margin:4px 0}.side-heading span{font-size:10px;color:var(--primary);font-weight:900;letter-spacing:.13em}.side-heading p{color:var(--muted);font-size:12px}.lesson-nav{display:grid;gap:5px}.group-label{font-size:11px;color:var(--muted);font-weight:800;margin:13px 6px 5px}.lesson-link{background:transparent;border:1px solid transparent;display:flex;align-items:center;text-align:left;gap:9px;padding:10px;border-radius:12px;width:100%;color:var(--text);min-width:0}.lesson-link .idx{min-width:28px;width:28px;height:28px;display:grid;place-items:center;background:var(--surface-soft);border:1px solid var(--border);border-radius:9px;color:var(--muted);font-size:11px}.lesson-link .label{font-size:12px;line-height:1.45;font-weight:650;flex:1}.lesson-link .done{font-size:13px;color:var(--primary);font-weight:800}.lesson-link:hover{background:var(--surface-soft)}.lesson-link.active{background:var(--tint);border-color:var(--primary)}.lesson-link.active .idx{background:var(--primary);color:light-dark(#fff,#18261d)}.side-footer{border-top:1px solid var(--border);margin-top:15px;padding-top:15px}.side-footer>a{font-size:12px;color:var(--primary);font-weight:800}.side-footer p{font-size:11px;color:var(--muted);margin:5px 0}.maincol{min-width:0;display:grid;gap:20px}.section-card{scroll-margin-top:16px;background:var(--surface);border:1px solid var(--border);border-radius:22px;padding:25px;box-shadow:var(--shadow);min-width:0}.lesson-header,.section-title{display:flex;justify-content:space-between;gap:14px;align-items:start}.lesson-header h2,.section-title h2{font-size:clamp(21px,2.5vw,29px);line-height:1.3;letter-spacing:-.035em;margin:5px 0 8px}.lesson-header p,.section-title p{font-size:13px;color:var(--muted);max-width:780px;margin:0}.difficulty{background:var(--tint);color:var(--primary);font-size:11px;padding:6px 11px;border-radius:99px;font-weight:800;white-space:nowrap}.pillrow{display:flex;flex-wrap:wrap;gap:8px;margin:17px 0 18px}.pillrow span{color:var(--muted);border:1px solid var(--border);border-radius:99px;font-size:11px;padding:4px 10px}.mini-title{font-size:16px;margin:15px 0 10px}.mini-title span{font-size:11px;color:var(--muted);font-weight:500}.concepts{display:grid;gap:9px}.concept{display:flex;align-items:start;gap:11px;padding:12px;background:var(--surface-soft);border:1px solid var(--border);border-radius:12px;font-size:13px}.concept>span{color:var(--primary);font-weight:850}.worked-example{margin-top:18px;background:var(--tint);padding:18px;border-radius:15px}.worked-example h3{margin:0 0 5px;font-size:17px}.worked-example p{margin:0;font-size:13px}.drawing-toolbar{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin:20px 0 11px}.switchers{display:flex;gap:4px;padding:4px;background:var(--surface-soft);border-radius:12px;border:1px solid var(--border)}.switchers button{border:0;color:var(--muted);background:transparent;padding:8px 13px;border-radius:9px;font-size:12px;font-weight:800}.switchers button.selected{background:var(--primary);color:light-dark(#fff,#152419)}.drawing-options{display:flex;align-items:center;gap:8px;font-size:12px;color:var(--muted)}select,input[type=number]{color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:9px;padding:8px 10px}.svg-panel{background:#fbfdfb;border:1px solid #d4e2d6;border-radius:16px;overflow:hidden}.svg-panel svg{display:block;width:100%;height:auto;min-height:205px}.drawing-key{display:flex;gap:13px;flex-wrap:wrap;background:#eff5f0;color:#5e7565;padding:8px 13px;font-size:11px}.dot{display:inline-block;width:8px;height:8px;border-radius:50%;margin-right:4px}.dot.green{background:#26734b}.dot.gold{background:#c08c3c}.coordinate-row{display:flex;gap:12px;flex-wrap:wrap;margin:12px 0}.coordinate-row label{display:flex;gap:8px;align-items:center;background:var(--surface-soft);border:1px solid var(--border);border-radius:11px;padding:6px 11px;color:var(--muted);font-size:12px}.coordinate-row input{width:125px;accent-color:var(--primary)}.coordinate-row output{color:var(--text);font-weight:850;min-width:23px;text-align:right}.player-controls{display:flex;align-items:center;gap:9px;flex-wrap:wrap;margin-top:14px}.speed-label{font-size:12px;color:var(--muted);margin-left:auto}.timeline{display:flex;align-items:center;gap:12px;margin:12px 0}.timeline input{width:100%;accent-color:var(--primary)}.timeline output{font-size:12px;font-weight:800;min-width:38px;text-align:right}.stage-description{background:var(--surface-soft);border-radius:12px;padding:13px 15px;font-size:13px}.stage-description p{margin:3px 0 0;color:var(--muted)}.note{font-size:11px;color:var(--muted);margin:13px 0 0}.steps{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:18px 0}.step{border:1px solid var(--border);background:var(--surface-soft);border-radius:13px;padding:13px;font-size:13px;display:flex;gap:11px}.step span{display:grid;place-items:center;width:29px;height:29px;flex-shrink:0;border:1px solid var(--border);background:var(--surface);border-radius:9px;font-weight:800;color:var(--primary)}.paper-assignment{display:flex;justify-content:space-between;gap:18px;align-items:center;background:var(--tint);padding:17px;border-radius:15px}.paper-assignment h3{font-size:16px;margin:2px 0}.paper-assignment p{font-size:13px;margin:0}.mistake-box{margin-top:15px;border:1px solid light-dark(#f5dfb5,#655439);border-radius:14px;background:var(--goldbg);padding:14px}.mistake-box h3{font-size:14px;margin:0 0 6px}.mistake-box p{font-size:12px;margin:5px 0}.mistake-box p::before{content:'· ';font-weight:900;color:var(--gold)}.filters{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin:20px 0 16px}.filters label{font-size:12px;color:var(--muted);display:flex;align-items:center;gap:8px}.question-frame{padding:22px;background:var(--surface-soft);border:1px solid var(--border);border-radius:17px}.question-meta{display:flex;align-items:center;gap:10px;font-size:11px;color:var(--muted)}.question-meta span:last-child{color:var(--primary);font-weight:800;background:var(--tint);border-radius:30px;padding:4px 8px}.question-frame h3{font-size:17px;line-height:1.65;margin:15px 0}.answers{display:grid;gap:8px}.choice{display:flex;align-items:center;gap:11px;text-align:left;width:100%;padding:11px 13px;border-radius:11px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:13px}.choice:hover{border-color:var(--primary)}.choice.selected{background:var(--tint);border-color:var(--primary)}.choice .choice-index{border-radius:6px;border:1px solid var(--border);height:25px;width:26px;display:grid;place-items:center;font-size:11px;color:var(--muted);flex-shrink:0}.answer-actions{display:flex;gap:9px;margin-top:16px}.numeric-answer{display:flex;align-items:center;gap:12px}.numeric-answer input{max-width:220px;width:100%;font-size:16px}.numeric-answer span{font-size:13px;color:var(--muted)}.order-list{display:grid;gap:7px}.order-item{display:flex;align-items:center;gap:9px;border:1px solid var(--border);border-radius:10px;background:var(--surface);padding:9px}.order-item .order-text{flex:1;font-size:12px}.order-item button{background:var(--surface-soft);color:var(--text);border:1px solid var(--border);border-radius:6px;padding:3px 8px;font-size:12px}.order-item button:disabled{opacity:.35}#questionFeedback{margin-top:13px;font-size:13px;border-radius:12px;min-height:0}#questionFeedback:not(:empty){padding:13px;background:var(--surface);border:1px solid var(--border)}#questionFeedback.correct{color:var(--primary)}#questionFeedback.wrong{color:var(--red)}.quiz-footer{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-top:13px;font-size:12px;color:var(--muted)}.text-button{background:none;border:0;color:var(--primary);font-size:12px;font-weight:800}.footer{border-top:1px solid var(--border);padding:26px 0 48px;color:var(--muted);font-size:12px}.footer p{margin:4px 0}.footer a{color:var(--primary)}
@media(max-width:900px){.layout{grid-template-columns:1fr}.sidepanel{position:static;max-height:none}.lesson-nav{grid-template-columns:repeat(2,minmax(0,1fr));gap:5px 10px}.group-label{grid-column:1/-1}.side-footer{display:none}.hero{grid-template-columns:1fr}.hero-metrics{max-width:none}.section-card{padding:19px}}
@media(max-width:560px){.wrap{width:calc(100% - 24px)}.top-inner{padding:11px 12px}.top-actions{gap:10px}.top-actions a{font-size:11px}.top-actions a:nth-child(2),.top-actions a:nth-child(3){display:none}.brand{font-size:15px}.brand small{font-size:8px}.hero{padding:25px 0}.hero h1{font-size:36px}.lesson-nav{grid-template-columns:1fr 1fr}.lesson-link{padding:7px;gap:5px}.lesson-link .label{font-size:11px}.sidepanel{padding:13px}.section-card{padding:16px;border-radius:16px}.steps{grid-template-columns:1fr}.paper-assignment{align-items:flex-start;flex-direction:column}.difficulty{font-size:10px}.svg-panel svg{min-height:155px}.drawing-key{font-size:10px}.drawing-toolbar{align-items:start}.switchers{width:100%;justify-content:space-around}.switchers button{font-size:11px;padding:8px}.coordinate-row input{width:90px}.speed-label{margin-left:0}.top-actions a:last-child{max-width:99px;white-space:nowrap;text-overflow:ellipsis;overflow:hidden}.question-frame{padding:13px}.hero-metrics{padding:17px}}
@media print{.topbar,.hero,.sidepanel,.player-controls,.timeline,.filters,.answer-actions,.quiz-footer,.drawing-toolbar,.hero-actions,#question-bank,.footer,.difficulty{display:none!important}.wrap{width:100%}.layout{display:block}.maincol{display:block}.section-card{page-break-inside:avoid;box-shadow:none;border:1px solid #ccc;margin-bottom:15px}.app,body{background:white;color:black}.concept,.step,.worked-example,.paper-assignment{background:white!important;color:black!important}.svg-panel{display:none}#workbench{display:none}.mistake-box{display:none}#method{page-break-before:always}}

.match-rows{display:grid;gap:9px}.match-row{display:flex;align-items:center;justify-content:space-between;gap:10px;background:var(--surface);border:1px solid var(--border);padding:10px 12px;border-radius:11px;font-size:13px}.match-row span{flex:1}.plot-board{max-width:300px;width:100%;aspect-ratio:1;display:block;margin:10px 0;border:1px solid var(--border);border-radius:12px;cursor:crosshair;touch-action:manipulation}.plot-hint,.plot-picked{font-size:12px;color:var(--muted)}@media(max-width:560px){.match-row{align-items:stretch;flex-direction:column}.match-row select{width:100%}}

/* 8.1 作图练习与课程导航补充样式 */
.practice-guide{color:var(--muted);font-size:12px;margin:0 0 12px}
.plot-tools{display:flex;align-items:center;flex-wrap:wrap;gap:12px;margin-top:8px}
.plot-tools .button{padding:7px 12px;min-height:34px}
.plot-tools p{margin:0}
:focus-visible{outline:3px solid var(--gold);outline-offset:3px}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}}

/* 题目内联自由度策略：与题目保持同一上下文，默认折叠。 */
.question-strategy{margin:14px 0;padding:12px;border:1px solid #cbded4;border-radius:12px;background:#f8fcfa}.question-strategy[hidden],#strategyDetail[hidden]{display:none}.question-strategy h4{margin:12px 0 6px}.question-strategy p{line-height:1.7}.question-strategy li{margin:8px 0;line-height:1.6}.strategy-note{font-size:.88rem;color:#55726d}