:root{--paper:#faf9f6;--surface:#fffdfb;--ink:#202d35;--muted:#6c7479;--line:#e1dfd8;--accent:#4677ac;--tint:#eaf1f8;--serif:Georgia,"Times New Roman","Songti SC",serif;--sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Helvetica Neue",sans-serif;font-family:var(--sans);color:var(--ink);background:var(--paper);color-scheme:light}*{box-sizing:border-box}body{margin:0}a{color:inherit;text-decoration:none}button,input,select{font:inherit;color:inherit}button,a{touch-action:manipulation}button{cursor:pointer;background:none;border:0}button:disabled{opacity:.35;cursor:default}a:focus-visible,button:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #b78b3e;outline-offset:4px}h1,h2,h3,p{margin:0}h1,h2,h3{font-weight:500}svg{display:block}img{max-width:100%}.skip{position:fixed;top:-80px;padding:15px;background:white;z-index:99}.skip:focus{top:0}#header{max-width:1440px;margin:auto;padding:23px 40px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);gap:20px}.brand{display:flex;align-items:center;gap:12px;font:25px var(--serif)}.brand img{width:37px;height:37px}.brand small{display:block;font:10px var(--sans);letter-spacing:.14em;color:var(--muted);margin-top:5px}.nav{display:flex;align-items:center;gap:28px}.nav>a,.account{font-size:13px;min-height:44px;display:flex;gap:6px;align-items:center}.nav>a[aria-current=page]{color:var(--accent)}.account{border-left:1px solid var(--line);padding-left:23px}.bi{display:flex;flex-direction:column;gap:4px}.bi small{color:var(--muted);font-size:11px;font-weight:400}.nav .bi small{font-size:10px}#main{max-width:1280px;margin:0 auto;padding:40px 0 64px;min-height:78vh}.eyebrow{color:var(--muted);font-size:11px;letter-spacing:.15em}.hero{display:flex;align-items:flex-end;justify-content:space-between;margin:8px 0 38px;gap:35px}.hero h1{font:46px/1.16 var(--serif);letter-spacing:-.035em;margin-top:14px}.hero h1 em{color:var(--accent);font-weight:400}.hero p{font-size:14px;color:var(--muted);line-height:1.9;max-width:330px}.hero .zh-title{font-size:16px;margin-top:14px;letter-spacing:.1em;color:#57636b}.chips{display:flex;gap:9px;margin-top:17px}.chip{font-size:10px;letter-spacing:.05em;border:1px solid var(--line);border-radius:25px;padding:7px 10px}.section-line{display:flex;align-items:center;justify-content:space-between;border-top:1px solid var(--line);padding:21px 0;font-size:12px;color:var(--muted)}.section-line strong{color:var(--ink);font-weight:500}.topics{display:grid;grid-template-columns:1fr 1fr;gap:23px}.topic-card{border:1px solid var(--line);border-radius:16px;background:var(--surface);overflow:hidden;transition:transform .2s,box-shadow .2s}.topic-card:hover{transform:translateY(-3px);box-shadow:0 12px 35px #3d34200c}.cover{height:155px;background:var(--tint);display:flex;align-items:center;justify-content:center;position:relative;overflow:hidden}.cover svg{width:330px;height:150px;color:var(--accent)}.cover-index{position:absolute;left:24px;top:20px;font:13px var(--serif);color:var(--accent)}.topic-copy{padding:22px 25px}.topic-copy h2{font:25px var(--serif);color:var(--ink)}.topic-copy p{font-size:13px;color:var(--muted);margin-top:8px}.topic-foot{display:flex;justify-content:space-between;align-items:center;margin-top:22px;font-size:12px;color:var(--accent)}.topic-foot span:last-child{font-size:20px}.start-strip{margin-top:28px;padding:20px 24px;border:1px solid var(--line);border-radius:12px;display:flex;gap:20px;align-items:center;justify-content:space-between;background:#fffdf9}.start-strip p{font-size:13px;color:var(--muted);line-height:1.9}.start-strip strong{font-weight:500;color:var(--ink)}.primary,.secondary{min-height:44px;padding:11px 19px;border-radius:8px;font-size:13px;display:inline-flex;align-items:center;justify-content:center;gap:8px}.primary{background:var(--accent);color:#fff;border:1px solid var(--accent)}.secondary{background:var(--surface);border:1px solid var(--line)}.quiet{color:var(--muted);font-size:12px;line-height:1.8}.crumb{display:flex;align-items:center;gap:8px;color:var(--muted);font-size:12px;margin-bottom:23px}.lesson-layout{display:grid;grid-template-columns:190px minmax(0,1fr);gap:36px}.lesson-sidebar{border-right:1px solid var(--line);padding-right:22px}.side-label{font-size:10px;letter-spacing:.1em;color:var(--muted);margin:6px 0 20px}.lesson-link{display:block;padding:15px 12px;border-radius:9px;margin-bottom:10px;position:relative}.lesson-link.active{background:var(--tint)}.lesson-link .num{font:13px var(--serif);color:var(--accent);margin-bottom:7px}.lesson-link strong{font-size:13px;font-weight:500;line-height:1.7;display:block}.lesson-link small{display:block;color:var(--muted);font-size:10px;margin-top:8px}.lesson-heading{display:flex;justify-content:space-between;gap:20px;align-items:flex-start;margin-bottom:26px}.lesson-heading h1{font:31px/1.25 var(--serif);margin:8px 0}.lesson-heading .zh{font-size:14px;color:var(--muted);line-height:1.6}.source-btn{font-size:11px;white-space:nowrap;min-height:40px;color:var(--muted);border:1px solid var(--line);border-radius:25px;padding:8px 13px}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 245px;border:1px solid var(--line);border-radius:16px;overflow:hidden;background:var(--surface)}.reading-stage{min-width:0;position:relative;padding:23px 27px 22px;--stage-height:205px}.stage-top{display:flex;justify-content:space-between;align-items:center;gap:12px;padding-bottom:20px}.stage-label{font-size:10px;letter-spacing:.12em;color:var(--accent)}.segmented{display:flex;background:#f0efea;border-radius:20px;padding:3px}.segmented button{font-size:11px;padding:6px 10px;border-radius:17px}.segmented button[aria-pressed=true]{background:var(--surface);box-shadow:0 1px 3px #0001}.passage{font:20px/1.95 var(--serif);min-height:var(--stage-height);position:relative;overflow-wrap:break-word}.fragment{transition:color .6s,background-color .6s,opacity .6s,box-shadow .6s;box-decoration-break:clone;-webkit-box-decoration-break:clone;border-radius:3px;padding:2px 0}.fragment.blank{white-space:nowrap;background:var(--tint);color:var(--accent);border-bottom:2px solid var(--accent);padding:2px 6px}.focused[data-step="1"] .fragment.extra,.focused[data-step="1"] .fragment.extra2,.focused[data-step="1"] .fragment.context,.focused[data-step="2"] .fragment.extra,.focused[data-step="2"] .fragment.extra2,.focused[data-step="2"] .fragment.context,.focused[data-step="3"] .fragment.extra,.focused[data-step="3"] .fragment.extra2,.focused[data-step="3"] .fragment.context{color:#8e969b;opacity:.5}.focused[data-step="1"] .subject,.focused[data-step="1"] .subject2,.focused[data-step="2"] .subject,.focused[data-step="2"] .subject2,.focused[data-step="3"] .subject,.focused[data-step="3"] .subject2{color:var(--accent);box-shadow:inset 0 -3px color-mix(in srgb,var(--accent) 40%,transparent)}[data-step="1"] .verb,[data-step="1"] .verb2,[data-step="2"] .verb,[data-step="2"] .verb2,[data-step="3"] .verb,[data-step="3"] .verb2{color:var(--accent);font-weight:bold}[data-step="1"] .modifier,[data-step="2"] .modifier,[data-step="3"] .modifier,[data-step="2"] .parallel1,[data-step="3"] .parallel1{background:var(--tint);color:var(--accent);box-shadow:inset 0 -2px var(--accent)}[data-step="2"] .link,[data-step="3"] .link{color:var(--accent);font-weight:bold}.micro-label{font-size:10px;color:var(--muted);margin:12px 0 13px;letter-spacing:.03em}.proof{position:relative;min-height:106px;display:grid;grid-template-columns:minmax(0,1fr) 34px minmax(0,1fr);gap:7px;align-items:center;border-top:1px solid var(--line);margin-top:12px;padding-top:20px}.proof-card{background:var(--tint);border:1px solid color-mix(in srgb,var(--accent) 20%,var(--line));padding:14px 10px;border-radius:9px;min-height:73px;text-align:center;transition:opacity .5s,transform .6s}.proof-card b{font:17px/1.35 var(--serif);display:block;color:var(--accent)}.proof-card small{font-size:11px;color:var(--muted);display:block;margin-top:7px}.proof[data-reveal="false"] .proof-card{opacity:0;transform:translateY(12px)}.proof[data-reveal="false"] .proof-arrow{opacity:0}.proof-arrow{transition:opacity .5s;color:var(--accent)}.proof-arrow path{stroke-dasharray:50;stroke-dashoffset:0;transition:stroke-dashoffset .8s}.proof[data-reveal="false"] .proof-arrow path{stroke-dashoffset:50}.bridge{font-size:10px;color:var(--accent);text-align:center;margin-top:11px;min-height:16px}.answer-pane{padding:26px 19px;border-left:1px solid var(--line);background:#fdfcf9}.answer-pane h2{font-size:10px;letter-spacing:.11em;color:var(--muted);margin-bottom:15px}.prompt{font:13px/1.6 var(--serif);margin-bottom:18px;color:#657079}.choice{display:flex;width:100%;gap:10px;align-items:flex-start;border:1px solid var(--line);border-radius:8px;padding:11px;margin:10px 0;text-align:left;font:15px/1.55 var(--serif);background:white;transition:border-color .3s,background .3s;overflow-wrap:anywhere}.choice .letter{display:flex;align-items:center;justify-content:center;flex:0 0 21px;height:21px;border:1px solid #d9dcdb;border-radius:50%;font:11px var(--sans);margin-top:1px}.choice[aria-pressed=true]{border-color:var(--accent);background:var(--tint)}.choice.correct{border-color:#357b68;background:#edf5ef}.choice.correct .letter{background:#357b68;color:white;border-color:#357b68}.choice.wrong{border-color:#b86f54;background:#f9eee8}.choice-hint{display:block;font:10px var(--sans);color:var(--muted);margin-top:5px}.choice.compact{font-size:13px}.answer-pane .primary{width:100%;margin-top:9px}.feedback{font-size:12px;color:var(--muted);line-height:1.8;margin-top:14px;min-height:42px}.feedback strong{display:block;color:var(--accent);font-weight:500;margin-bottom:4px}.teaching-copy{padding:24px 0 0;min-height:133px}.teaching-kicker{font-size:11px;color:var(--accent);display:flex;gap:9px;align-items:center}.step-num{width:20px;height:20px;border:1px solid var(--accent);border-radius:50%;display:inline-flex;align-items:center;justify-content:center;font-size:10px}.teaching-copy h2{font-size:21px;margin:10px 0 9px;line-height:1.5}.teaching-copy p{font-size:14px;line-height:1.9;color:#68737a;max-width:780px}.controls{display:flex;align-items:center;justify-content:space-between;gap:12px;border-top:1px solid var(--line);margin-top:18px;padding-top:17px}.step-dots{display:flex;gap:8px}.step-dot{width:28px;height:28px;border:1px solid var(--line);border-radius:50%;font-size:10px}.step-dot[aria-current=step]{background:var(--accent);color:#fff;border-color:var(--accent)}.control-buttons{display:flex;gap:9px;align-items:center}.icon-btn{width:36px;height:36px;border:1px solid var(--line);border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:12px}.time-control{display:flex;gap:13px;align-items:center;margin-top:14px}.time-control input{width:100%;accent-color:var(--accent);height:18px}.time-control span{font-size:10px;color:var(--muted);white-space:nowrap}.rule{background:var(--tint);border-left:2px solid var(--accent);padding:15px 18px;margin-top:22px;font-size:13px;line-height:1.8}.rule[hidden]{display:none}.next-lesson{display:flex;justify-content:space-between;border-top:1px solid var(--line);margin-top:30px;padding-top:20px;font-size:12px;color:var(--muted)}.map-intro h1,.review h1{font:38px var(--serif);margin:12px 0}.map-intro p{font-size:14px;color:var(--muted);line-height:1.9}.map-grid{display:grid;grid-template-columns:1fr 1fr;gap:23px;margin:30px 0}.map-card{border:1px solid var(--line);border-radius:14px;padding:25px;background:var(--surface)}.map-card h2{font:23px var(--serif);color:var(--accent)}.map-card h3{font-size:13px;margin-top:7px;color:var(--muted)}.map-card ul{list-style:none;margin:22px 0;padding:0}.map-card li{border-top:1px solid var(--line);padding:11px 0;font-size:13px;display:flex;gap:12px}.map-card li span{font-size:10px;color:var(--accent)}.scope-note{font-size:12px;color:var(--muted);line-height:1.9;padding:20px;border:1px solid var(--line);border-radius:10px}.scope-note a{color:var(--accent);text-decoration:underline}.review-list{margin-top:25px}.review-row{padding:21px 0;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);gap:20px}.review-row h2{font-size:17px}.review-row p{font-size:12px;color:var(--muted);margin-top:8px}.empty{padding:50px 0;font-size:14px;line-height:1.9;color:var(--muted)}footer{max-width:1280px;margin:auto;padding:24px 0 35px;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:16px;color:var(--muted);font-size:11px}dialog{max-width:460px;width:calc(100% - 32px);background:var(--paper);border:1px solid var(--line);border-radius:16px;padding:26px;color:var(--ink)}dialog::backdrop{background:#1e2d3d66;backdrop-filter:blur(4px)}dialog.wide{max-width:1050px}.modal-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px;gap:15px}.modal-head h2{font:25px var(--serif)}.close{font-size:25px;width:36px;height:36px}.account-copy{font-size:13px;color:var(--muted);line-height:1.9;margin-bottom:22px}.account-form{display:grid;gap:17px}.account-form label{font-size:12px;display:grid;gap:8px}.account-form input{border:1px solid #c7cacb;border-radius:8px;background:white;padding:12px;min-width:0;min-height:44px}.error{font-size:12px;color:#a14e34;line-height:1.8}.switch{font-size:12px;color:var(--accent);margin-top:17px;min-height:35px}.original-text{font:17px/1.9 var(--serif);margin:20px 0}.source-detail{font-size:11px;color:var(--muted);line-height:1.9;border-top:1px solid var(--line);padding-top:18px}.original-options p{font:15px/1.8 var(--serif);margin:8px 0}#toast{position:fixed;bottom:25px;left:50%;transform:translateX(-50%);color:white;background:#283933;max-width:90%;border-radius:9px;padding:13px 20px;font-size:12px;z-index:99;display:none}#toast.show{display:block}.admin-table{width:100%;border-collapse:collapse;margin-top:25px;font-size:13px}.admin-table td,.admin-table th{text-align:left;padding:17px 12px;border-bottom:1px solid var(--line);font-weight:400}.admin-table th{color:var(--muted)}@media(min-width:1440px){.hero h1{font-size:50px}}@media(max-width:1380px){#main,footer{margin-left:40px;margin-right:40px}}@media(max-width:1100px){.lesson-layout{grid-template-columns:150px minmax(0,1fr);gap:23px}.workspace{grid-template-columns:minmax(0,1fr) 215px}.reading-stage{padding:21px}.passage{font-size:18px}.lesson-heading h1{font-size:26px}.proof-card b{font-size:15px}.lesson-sidebar{padding-right:14px}.nav{gap:20px}}@media(max-width:900px){.lesson-layout{grid-template-columns:1fr}.lesson-sidebar{display:flex;gap:7px;border:0;padding:0;overflow-x:auto}.lesson-sidebar .side-label,.lesson-sidebar>.quiet{display:none}.lesson-link{flex:0 0 170px;margin:0;padding:11px}.lesson-link strong{font-size:12px}.lesson-link small{font-size:9px}.lesson-link .num{margin-bottom:3px}.hero h1{font-size:39px}.hero p{max-width:270px;font-size:13px}.topic-copy h2{font-size:23px}.workspace{grid-template-columns:minmax(0,1fr) 240px}}@media(max-width:640px){#header{padding:18px 20px 10px;flex-wrap:wrap;gap:16px}.brand{font-size:23px}.brand img{width:32px;height:32px}.nav{width:100%;justify-content:space-between;gap:12px}.nav>a,.account{font-size:11px}.account{padding-left:12px}.nav .bi small{font-size:9px}#main{margin:0 20px;padding-top:28px}.hero{display:block;margin-bottom:28px}.hero h1{font-size:40px}.hero p{max-width:none;margin-top:22px;font-size:13px}.hero .zh-title{font-size:14px}.topics{grid-template-columns:1fr;gap:20px}.cover{height:150px}.topic-copy{padding:21px}.topic-copy h2{font-size:24px}.start-strip{align-items:flex-start;flex-direction:column}.lesson-heading{display:block;margin-bottom:20px}.source-btn{margin-top:14px}.lesson-heading h1{font-size:29px}.workspace{grid-template-columns:1fr}.reading-stage{padding:21px 19px}.passage{font-size:19px;line-height:2;min-height:200px}.answer-pane{border-left:0;border-top:1px solid var(--line);padding:21px 19px}.answer-pane .prompt{display:none}.answer-pane h2{margin-bottom:10px}.choice{font-size:16px;margin:9px 0;padding:11px}.choice.compact{font-size:14px}.feedback{min-height:0}.proof-card b{font-size:16px}.stage-top{gap:5px}.stage-label{font-size:9px}.segmented button{font-size:10px;padding:6px 9px}.teaching-copy{min-height:155px}.teaching-copy h2{font-size:21px}.teaching-copy p{font-size:14px}.controls{flex-wrap:wrap}.control-buttons .primary,.control-buttons .secondary{padding:10px 13px;font-size:12px;min-height:41px}.step-dots{gap:6px}.step-dot{width:26px;height:26px}.control-buttons{gap:6px}.icon-btn{width:32px;height:32px}.map-grid{grid-template-columns:1fr}.map-intro h1{font-size:32px}footer{margin:0 20px;font-size:10px}footer span:nth-child(2){display:none}.admin-table td,.admin-table th{padding:14px 5px;font-size:12px}.next-lesson{gap:20px;line-height:1.7}.review-row h2{font-size:15px}.original-text{font-size:16px}.source-detail{overflow-wrap:anywhere}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
/* Keep the explanation controls within reach while reading a long question. */
.controls{position:sticky;bottom:0;background:var(--paper);z-index:5;padding-bottom:12px;box-shadow:0 -12px 18px var(--paper)}
@media(max-width:640px){.controls{bottom:0;margin-left:-5px;margin-right:-5px;padding-left:5px;padding-right:5px}.section-line{line-height:1.7;gap:20px;align-items:flex-start}.section-line>span{font-size:10px;text-align:right;max-width:90px}.hero h1{font-size:38px}}
.reading-stage .teaching-copy{padding:0 0 19px;min-height:0}.reading-stage .teaching-copy h2{font-size:19px;margin:8px 0}.reading-stage .teaching-copy p{font-size:13px;line-height:1.85}.reading-stage .passage{min-height:0;padding-bottom:14px}.reading-stage .stage-top{padding-bottom:18px}.reading-stage .proof{min-height:96px;padding-top:16px}.reading-stage .micro-label{margin-top:10px}
@media(max-width:640px){.reading-stage .teaching-copy h2{font-size:19px}.reading-stage .teaching-copy p{font-size:13px}.reading-stage .passage{font-size:18px;line-height:1.95}.reading-stage .stage-top{padding-bottom:20px}.reading-stage .teaching-copy{padding-bottom:22px}}
/* Step 2 preserves the full reading; step 3 compresses the two modifiers. */
.focused[data-step="2"] .fragment.context,.focused[data-step="2"] .fragment.extra,.focused[data-step="2"] .fragment.extra2,.focused[data-step="3"] .fragment.context,.focused[data-step="3"] .fragment.extra,.focused[data-step="3"] .fragment.extra2{font-size:0;opacity:.7;transition:font-size .6s,color .6s,opacity .6s}
.focused[data-step="2"] .fragment.context::after,.focused[data-step="2"] .fragment.extra::after,.focused[data-step="2"] .fragment.extra2::after,.focused[data-step="3"] .fragment.context::after,.focused[data-step="3"] .fragment.extra::after,.focused[data-step="3"] .fragment.extra2::after{content:attr(data-short);font:13px/1.8 var(--sans);color:var(--muted);white-space:nowrap;padding:0 4px}
@media(max-width:640px){.lesson-sidebar{gap:8px}.lesson-link{flex:1 0 auto;padding:9px 11px;text-align:center}.lesson-link strong,.lesson-link small{display:none}.lesson-link .num{margin:0;font-size:11px}.crumb{font-size:10px;margin-bottom:16px;line-height:1.7;flex-wrap:wrap;gap:6px}.lesson-layout{gap:24px}.lesson-heading h1{font-size:27px;line-height:1.2}.lesson-heading .zh{font-size:13px}.lesson-heading{margin-bottom:18px}#main{padding-top:24px}.reading-stage .stage-label{font-size:8px}}