:root{--bg:#f6f7f5;--panel:#fff;--panel-strong:#f9fbf8;--text:#17211f;--muted:#66716d;--line:#dfe6e2;--line-strong:#c8d5cf;--green:#07866c;--green-dark:#026a58;--green-soft:#e7f4ef;--amber:#f59f18;--amber-soft:#fff5df;--shadow:0 18px 42px #17211f14;color:var(--text);background:var(--bg);font-family:Inter,Noto Sans SC,Microsoft YaHei,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}*{box-sizing:border-box}body{background:var(--bg);min-width:320px;margin:0}button,input,textarea{font:inherit}button{cursor:pointer}.app-shell{grid-template-rows:96px 1fr;grid-template-columns:280px 1fr;min-height:100vh;display:grid}.topbar{border-bottom:1px solid var(--line);z-index:20;-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);background:#fffffff0;grid-column:1/-1;align-items:center;gap:24px;padding:18px 30px;display:flex;position:sticky;top:0}.brand{align-items:center;gap:14px;min-width:300px;display:flex}.brand>div{min-width:0}.brand-mark{width:44px;height:44px;color:var(--green);border:2px solid var(--green);border-radius:8px;flex:none;place-items:center;display:grid}.brand h1{letter-spacing:0;margin:0;font-size:21px;line-height:1.25}.brand p{color:var(--muted);margin:4px 0 0;font-size:13px}.mode-tabs{flex:1;justify-content:center;gap:10px;min-width:0;display:flex}.mode-button,.ghost-button,.icon-label-button,.primary-button,.secondary-button,.icon-button{border:1px solid var(--line);background:var(--panel);color:var(--text);border-radius:8px;justify-content:center;align-items:center;gap:8px;min-height:42px;transition:border-color .16s,background .16s,color .16s,transform .16s;display:inline-flex}.mode-button{color:#4d5a56;background:0 0;border-color:#0000;padding:0 18px}.mode-button.active{color:var(--green-dark);background:var(--green-soft);border-color:#b9ded3;font-weight:700}.ghost-button{white-space:nowrap;padding:0 16px}.icon-button{width:42px;padding:0}.sidebar{border-right:1px solid var(--line);background:#fbfcfb;padding:24px 16px;overflow-y:auto}.sidebar section+section{margin-top:24px}.sidebar h2,.progress-card h2,.outline-card h2{margin:0 0 14px;font-size:16px;line-height:1.35}.nav-row{color:#43504c;text-align:left;background:0 0;border:1px solid #0000;border-radius:8px;grid-template-columns:24px 1fr auto;align-items:center;gap:10px;width:100%;min-height:52px;padding:0 12px;display:grid}.nav-row svg{color:var(--green)}.nav-row b{border:1px solid var(--line-strong);color:#52615d;background:#fff;border-radius:999px;place-items:center;min-width:31px;height:26px;font-size:13px;display:inline-grid}.nav-row.active{background:var(--green-soft);color:var(--green-dark);border-color:#bfddd5;font-weight:700}.nav-row.active b{background:var(--green);color:#fff;border-color:var(--green)}.guide-panel{border:1px solid var(--line);background:var(--panel);border-radius:8px;padding:16px}.guide-panel p{color:var(--muted);margin:0;font-size:14px;line-height:1.65}.mini-stat{border-top:1px solid var(--line);color:var(--muted);justify-content:space-between;align-items:center;margin-top:15px;padding-top:14px;display:flex}.mini-stat strong{color:var(--green-dark)}.workspace{grid-template-columns:minmax(300px,430px) minmax(420px,1fr) minmax(280px,360px);align-items:start;gap:18px;min-width:0;padding:18px;display:grid}.list-panel,.study-card,.progress-card,.outline-card{background:var(--panel);border:1px solid var(--line);box-shadow:var(--shadow);border-radius:8px}.list-panel{min-height:calc(100vh - 132px);padding:18px}.search-box{border:1px solid var(--line-strong);color:#7c8884;background:#fff;border-radius:8px;align-items:center;gap:10px;height:46px;padding:0 14px;display:flex}.search-box input{width:100%;color:var(--text);background:0 0;border:0;outline:0;font-size:14px}.list-meta{color:var(--muted);justify-content:space-between;margin:16px 0 10px;font-size:13px;display:flex}.question-list{gap:8px;display:grid}.question-row{border:1px solid var(--line);text-align:left;background:#fff;border-radius:8px;grid-template-columns:34px 1fr auto;align-items:center;gap:10px;width:100%;min-height:80px;padding:12px;display:grid}.question-row.selected{border-color:var(--green);box-shadow:inset 3px 0 0 var(--green);background:linear-gradient(90deg,#f0faf6 0%,#fff 70%)}.number{color:#66716d;font-size:18px;font-weight:800}.question-main strong{font-size:15px;line-height:1.45;display:block}.question-main small{color:var(--green-dark);margin-top:5px;font-size:12px;display:block}.row-actions{color:#9aa4a0;gap:6px;display:inline-flex}.row-actions .favorite{color:var(--amber)}.row-actions .mastered{color:var(--green)}.study-card{flex-direction:column;min-height:calc(100vh - 132px);padding:24px;display:flex}.card-kicker{gap:10px;margin-bottom:18px;display:flex}.card-kicker span{background:var(--amber-soft);color:#a96205;border:1px solid #f3d2a1;border-radius:8px;align-items:center;min-height:34px;padding:0 10px;font-weight:700;display:inline-flex}.card-kicker span+span{color:var(--green-dark);background:var(--green-soft);border-color:#b7ddd4}.card-title-row{justify-content:space-between;align-items:flex-start;gap:18px;display:flex}.card-title-row h2{letter-spacing:0;margin:0;font-size:30px;line-height:1.28}.card-title-row p{color:var(--muted);margin:12px 0 0;line-height:1.7}.icon-label-button{color:#596662;flex:none;padding:0 12px}.icon-label-button.active{color:#b66b00;background:var(--amber-soft);border-color:#f2cf97}.tag-row{flex-wrap:wrap;gap:8px;margin:18px 0 20px;display:flex}.tag-row span{min-height:28px;color:var(--green-dark);background:#edf6f2;border:1px solid #c8e4dc;border-radius:8px;align-items:center;padding:0 9px;font-size:13px;display:inline-flex}.write-box{margin-bottom:18px}.write-box label{color:#3a4945;margin-bottom:8px;font-size:14px;font-weight:700;display:block}.write-box textarea{resize:vertical;border:1px solid var(--line-strong);border-radius:8px;outline:none;width:100%;min-height:150px;padding:13px 14px;line-height:1.7}.write-box textarea:focus,.search-box:focus-within{border-color:var(--green);box-shadow:0 0 0 3px #07866c1f}.answer-panel{border:1px dashed var(--line-strong);background:#fcfdfc;border-radius:8px;flex:1;align-content:center;min-height:300px;display:grid;overflow:hidden}.answer-panel.revealed{background:#fff;border-style:solid;display:block}.answer-panel ol{gap:14px;margin:0;padding:22px 26px 22px 48px;display:grid}.answer-panel li{padding-left:5px;line-height:1.75}.answer-panel li::marker{color:var(--green);font-weight:800}.mind-map{border:1px solid var(--line);background-color:#fcfdfc;background-image:linear-gradient(90deg,#07866c0f 1px,#0000 1px),linear-gradient(#07866c0f 1px,#0000 1px),none;background-position:0 0,0 0,0 0;background-repeat:repeat,repeat,repeat;background-size:28px 28px;background-attachment:scroll,scroll,scroll;background-origin:padding-box,padding-box,padding-box;background-clip:border-box,border-box,border-box;border-radius:8px;flex:1;grid-template-columns:1fr;align-items:start;gap:16px;min-height:360px;padding:24px;display:grid;overflow:hidden}.mind-map-center{border:2px solid var(--green);text-align:center;background:#fff;border-radius:8px;align-content:center;place-items:center;gap:10px;min-height:142px;padding:20px 16px;display:grid;position:relative;box-shadow:0 18px 36px #07866c1f}.mind-map-center span{color:var(--green-dark);font-size:13px;font-weight:800}.mind-map-center strong{font-size:24px;line-height:1.25}.mind-map-center small{color:#8a5600;background:var(--amber-soft);border:1px solid #f1cd95;border-radius:8px;padding:6px 8px;line-height:1.45}.mind-map-branches{grid-template-columns:1fr;gap:12px;display:grid}.mind-branch{border:1px solid var(--line);border-left:4px solid var(--green);background:#fffffff0;border-radius:8px;min-height:0;padding:14px 14px 14px 48px}.mind-branch b{background:var(--green);color:#fff;border-radius:50%;place-items:center;width:24px;height:24px;font-size:13px;display:grid;position:absolute;top:14px;left:14px}.mind-branch h3{color:var(--green-dark);margin:0 0 7px;font-size:15px;line-height:1.4}.mind-branch p{color:#3f4e4a;margin:0;font-size:14px;line-height:1.65}.hidden-answer{min-height:298px;color:var(--muted);text-align:center;align-content:center;place-items:center;gap:9px;display:grid}.hidden-answer svg{color:var(--green)}.hidden-answer strong{color:var(--text);font-size:18px}.study-actions{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:10px;margin-top:22px;display:flex}.primary-button,.secondary-button{min-height:46px;padding:0 16px;font-weight:700}.primary-button{color:#fff;border-color:var(--green);background:var(--green)}.secondary-button{color:#41514d;background:#fff}.secondary-button.is-mastered{background:var(--green-soft);color:var(--green-dark);border-color:#b9ded3}.progress-panel{gap:18px;display:grid}.progress-card,.outline-card{padding:18px}.progress-card p{color:var(--muted);margin:-7px 0 16px;font-size:13px}.progress-ring{background:radial-gradient(circle at center, #fff 0 55%, transparent 56%), conic-gradient(var(--green) var(--progress), #e8eeeb 0);border-radius:50%;place-items:center;width:132px;height:132px;margin:8px auto 18px;display:grid}.progress-ring strong{color:var(--green-dark);font-size:30px}.progress-grid{grid-template-columns:repeat(3,1fr);gap:10px;margin:0;display:grid}.progress-grid div{background:var(--panel-strong);border:1px solid var(--line);text-align:center;border-radius:8px;padding:12px 8px}.progress-grid dt{color:var(--muted);font-size:12px}.progress-grid dd{color:var(--green-dark);margin:5px 0 0;font-size:18px;font-weight:800}.outline-title{color:var(--green-dark);align-items:center;gap:8px;display:flex}.outline-card ul{gap:14px;margin:0;padding:0;list-style:none;display:grid}.outline-card li{grid-template-columns:28px 1fr;align-items:start;gap:10px;display:grid}.outline-card li b{background:var(--green);color:#fff;border-radius:50%;place-items:center;width:25px;height:25px;font-size:13px;display:grid}.outline-card li span{color:#344540;font-size:14px;line-height:1.65}.formula-box{background:var(--amber-soft);border:1px solid #f1cd95;border-radius:8px;padding:14px}.formula-box strong{color:#8a5600;font-size:18px;line-height:1.55;display:block}.formula-box p{color:#6c6252;margin:8px 0 0;font-size:14px;line-height:1.6}.empty-state{border:1px dashed var(--line-strong);color:var(--muted);text-align:center;border-radius:8px;padding:26px 12px}.mobile-only{display:none}@media (hover:hover){.mode-button:hover,.ghost-button:hover,.icon-label-button:hover,.secondary-button:hover,.icon-button:hover,.question-row:hover,.nav-row:hover{border-color:var(--green)}.primary-button:hover{background:var(--green-dark);transform:translateY(-1px)}}@media (width<=1220px){.app-shell{grid-template-columns:240px 1fr}.workspace{grid-template-columns:minmax(290px,390px) minmax(390px,1fr)}.progress-panel{grid-column:1/-1;grid-template-columns:320px 1fr}}@media (width<=920px){.app-shell{display:block}.topbar{flex-wrap:wrap;gap:12px;padding:14px 16px}.brand{flex:1;min-width:0}.brand h1{white-space:nowrap;text-overflow:ellipsis;font-size:17px;overflow:hidden}.brand p{display:none}.brand-mark{width:38px;height:38px}.mode-tabs{flex:0 0 100%;order:3;justify-content:flex-start;width:100%;padding-bottom:2px;overflow-x:auto}.mode-button{flex:none;min-height:38px;padding:0 12px}.ghost-button{flex:0 0 40px;order:2;gap:0;width:40px;min-height:38px;padding:0 11px;font-size:0}.mobile-only{display:inline-flex}.sidebar{z-index:40;width:min(320px,88vw);transition:transform .18s;position:fixed;inset:0 auto 0 0;transform:translate(-105%);box-shadow:18px 0 38px #0c181524}.sidebar.open{transform:translate(0)}.sidebar-header{justify-content:space-between;align-items:center;margin-bottom:16px}.scrim{z-index:30;background:#121e1b57;border:0;position:fixed;inset:0}.workspace{grid-template-columns:1fr;padding:14px}.study-card{order:1}.list-panel{order:2}.progress-panel{order:3}.list-panel,.study-card{min-height:auto}.progress-panel{grid-template-columns:1fr}}@media (width<=620px){.topbar{position:relative}.workspace{gap:12px;padding:10px}.list-panel,.study-card,.progress-card,.outline-card{box-shadow:none;border-radius:8px}.list-panel,.study-card{padding:14px}.card-title-row{display:grid}.card-title-row h2{font-size:24px}.icon-label-button{justify-self:start}.study-actions{grid-template-columns:1fr;display:grid}.answer-panel{min-height:220px}.hidden-answer{min-height:218px}.mind-map{min-height:0;padding:14px}.mind-map-center strong{font-size:22px}.primary-button,.secondary-button{width:100%}.question-row{grid-template-columns:30px 1fr auto}}