:root{--canvas: #f3f6ef;--surface: #fffdf7;--surface-soft: #eaf1e6;--ink: #24342b;--muted: #6c7b70;--line: #d7e1d3;--accent: #4f7059;--accent-dark: #3d5d47;--warm: #f5efd9;--danger: #a34f47;--shadow: 0 10px 28px rgba(45, 65, 49, .08)}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;min-width:320px;color:var(--ink);background:var(--canvas);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Microsoft YaHei,sans-serif;line-height:1.72}button,input{font:inherit}button{border:1px solid var(--line);border-radius:7px;background:var(--surface);color:var(--ink);cursor:pointer;min-height:36px;padding:7px 10px;transition:background .18s ease,border-color .18s ease,transform .18s ease}button:hover{background:var(--surface-soft);border-color:#b9cdb8}button:active{transform:translateY(1px)}.app-shell{min-height:100vh}.app-error{display:grid;place-items:center;align-content:center;gap:12px;min-height:100vh;padding:24px;text-align:center}.app-error h1{margin:0;font-size:clamp(26px,4vw,42px)}.app-error p{max-width:520px;margin:0;color:var(--muted)}.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:12px;padding:12px clamp(14px,3vw,30px);border-bottom:1px solid var(--line);background:#f3f6eff0;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px)}.brand{flex:1;min-width:180px}.kicker{color:var(--muted);font-size:12px;line-height:1.2;outline:none}.page-title{margin:2px 0 0;font-size:clamp(21px,2.8vw,30px);line-height:1.25;outline:none}.top-actions{display:flex;flex-wrap:wrap;justify-content:flex-end;gap:7px}.action-button{font-size:13px}.action-button.primary{background:var(--accent);color:#fff;border-color:var(--accent)}.action-button.primary:hover{background:var(--accent-dark);color:#fff}.action-button.selected{background:var(--warm);border-color:#d8c98f}.action-button.subtle{color:var(--muted)}.button-icon{display:inline-block;margin-right:4px;font-weight:700}.icon-button{display:inline-grid;place-items:center;width:38px;padding:0;flex:0 0 auto}.icon-button.small{width:32px;min-height:32px}.danger{color:var(--danger)}.small-button{min-height:32px;padding:5px 8px;font-size:12px}.workspace{display:grid;grid-template-columns:minmax(235px,290px) minmax(0,1fr);gap:22px;max-width:1460px;margin:0 auto;padding:22px clamp(14px,3vw,32px) 60px}.sidebar{position:sticky;top:84px;height:calc(100vh - 106px);overflow:auto;padding:13px;border:1px solid var(--line);border-radius:9px;background:#fffdf7db;box-shadow:var(--shadow)}.sidebar-heading{display:flex;align-items:center;justify-content:space-between;gap:8px}.sidebar-title{font-size:15px;font-weight:750;outline:none}.sidebar-actions{margin:12px 0}.chapter-nav{display:grid;gap:9px}.nav-home{width:100%;justify-content:flex-start;text-align:left;font-weight:750}.nav-home.active,.nav-chapter.active .chapter-switch{background:var(--surface-soft);border-color:#b6cab2}.nav-chapter{border-top:1px solid var(--line);padding-top:9px}.nav-chapter.dragging{opacity:.58}.chapter-nav details{margin:0}.chapter-nav summary{list-style:none}.chapter-nav summary::-webkit-details-marker{display:none}.chapter-switch{display:grid;grid-template-columns:auto minmax(0,1fr) auto;align-items:center;gap:7px;width:100%;min-height:38px;text-align:left;font-weight:750}.drag-handle{color:var(--muted);cursor:grab;font-size:14px}.chapter-switch-title{overflow:hidden;text-overflow:ellipsis}.chapter-count{color:var(--muted);font-size:12px;font-weight:500}.chapter-order-tools{display:flex;gap:6px;padding:7px 0 2px}.mini-button{min-height:28px;padding:3px 8px;color:var(--muted);font-size:12px}.mini-button:disabled{opacity:.42;cursor:not-allowed}.nav-sections{display:grid;gap:9px;margin-top:8px}.nav-section{display:grid;gap:4px}.nav-section-link{display:block;width:100%;padding:6px 7px;border-radius:6px;border:0;color:#344a3b;font-size:13px;font-weight:700;text-align:left;text-decoration:none;background:#eaf1e6b3}.nav-section-link:hover{background:var(--surface-soft)}.nav-items{display:grid;gap:3px;padding-left:8px;border-left:2px solid var(--line)}.nav-items button{display:block;width:100%;min-height:0;padding:6px 8px;border:0;border-radius:6px;color:var(--muted);font-size:12px;line-height:1.4;text-align:left;text-decoration:none;background:transparent}.nav-items button:hover{background:var(--surface-soft);color:var(--ink)}.nav-items em{color:var(--muted);font-size:12px;padding:5px 8px}.content{min-width:0}.content-toolbar{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:14px;color:var(--muted);font-size:13px}.search-box{display:flex;align-items:center;gap:6px;width:min(370px,100%);padding:0 10px;border:1px solid var(--line);border-radius:7px;background:var(--surface)}.search-box input{width:100%;min-height:36px;border:0;outline:0;background:transparent;color:var(--ink)}.home-panel{display:grid;gap:18px;padding:clamp(18px,3vw,30px);border:1px solid var(--line);border-radius:10px;background:var(--surface);box-shadow:var(--shadow)}.home-copy h2{margin:0 0 6px;font-size:clamp(26px,4vw,40px);line-height:1.2}.home-copy p{max-width:680px;margin:0;color:var(--muted)}.home-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:12px}.home-card{display:grid;gap:7px;align-content:start;min-height:112px;padding:16px;text-align:left;background:#fbfaf2}.home-card span{font-size:18px;font-weight:760;line-height:1.35}.home-card small{color:var(--muted)}.chapter{scroll-margin-top:92px;margin-bottom:30px}.chapter-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;margin:16px 0 14px}.chapter-title{margin:0;font-size:clamp(25px,4vw,38px);line-height:1.2;outline:none}.chapter-tools,.section-tools,.item-actions{display:flex;flex-wrap:wrap;justify-content:flex-end;gap:6px}.content-section{scroll-margin-top:92px;margin:0 0 22px}.section-heading{display:flex;align-items:center;justify-content:space-between;gap:10px;margin:10px 0 12px}.section-title{margin:0;color:#36513f;font-size:clamp(19px,2.4vw,26px);line-height:1.25;outline:none}.items{display:grid;gap:14px}.study-item{position:relative;overflow:hidden;border:1px solid var(--line);border-radius:9px;background:var(--surface);box-shadow:var(--shadow);scroll-margin-top:92px}.item-header{display:flex;align-items:flex-start;justify-content:space-between;gap:10px;padding:17px clamp(16px,2.4vw,26px) 8px}.item-question{flex:1;min-width:0;margin:0;color:#203429;font-size:clamp(21px,2.55vw,30px);line-height:1.35;outline:none;word-break:break-word}.item-answer{padding:7px clamp(16px,2.4vw,26px) 21px;color:#3b4a41;font-size:clamp(15px,1.5vw,18px);outline:none;word-break:break-word}.item-answer p{margin:0 0 .85em}.item-answer p:last-child{margin-bottom:0}[contenteditable=true]:focus{box-shadow:inset 0 0 0 2px #4f705933;border-radius:5px}.mask-answer .item-answer,.mask-question .item-question{min-height:56px;color:transparent;-webkit-user-select:none;user-select:none;border-radius:7px;background:repeating-linear-gradient(135deg,#dce8d8 0 10px,#cfe0cb 10px 20px)}.mask-answer .item-answer:after,.mask-question .item-question:after{content:"点击显示";position:absolute;left:0;right:0;display:grid;place-items:center;min-height:56px;color:#52665a;font-weight:700}.masked-text{padding:0 .18em;border-radius:4px;background:#d3e2ce;color:transparent;cursor:pointer;-webkit-user-select:none;user-select:none}.masked-text.revealed{color:inherit;background:#edf4e9;-webkit-user-select:text;user-select:text}.reveal-hint{position:absolute;right:18px;bottom:12px;min-height:30px;border-color:#bfceb9;background:var(--surface-soft);font-size:12px}.empty-chapter,.empty-state{padding:26px;border:1px dashed #b9cbb6;border-radius:8px;color:var(--muted);background:#fffdf7a6}.empty-state{text-align:center}.toast{position:fixed;right:18px;bottom:18px;z-index:50;padding:9px 13px;border-radius:7px;color:#fff;background:#26372d;font-size:13px;box-shadow:var(--shadow)}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}@media(max-width:1050px){.topbar{align-items:flex-start;flex-wrap:wrap}.top-actions{width:100%;justify-content:flex-start}.workspace{grid-template-columns:1fr;padding-top:14px}.sidebar{position:fixed;z-index:15;top:82px;left:12px;right:12px;height:min(70vh,620px)}.app-shell:not(.sidebar-open) .sidebar{display:none}.app-shell:not(.sidebar-open) .content{margin-top:0}.app-shell.sidebar-open .content{margin-top:min(72vh,640px)}}@media(max-width:640px){.top-actions button{flex:1 1 auto}.content-toolbar,.chapter-heading,.section-heading,.item-header{display:grid}.search-box{width:100%}.chapter-tools,.section-tools,.item-actions{justify-content:flex-start}.item-question{font-size:22px}.item-answer{font-size:16px}}@media print{.topbar,.sidebar,.content-toolbar,.chapter-tools,.item-actions,.reveal-hint{display:none!important}.workspace{display:block;padding:0}.study-item{box-shadow:none;break-inside:avoid}}