:root{--ink:#142235;--muted:#66758b;--blue:#2f6fed;--line:#e1e8f0;--bg:#f4f7fb;--green:#16845c}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:15px/1.7 "Microsoft YaHei UI","PingFang SC",Arial,sans-serif}button,input,select,textarea{font:inherit}button,a,select{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:wait;opacity:.5}a{color:var(--blue);text-decoration:none}button:focus-visible,a:focus-visible,select:focus-visible{outline:3px solid #99b9ff;outline-offset:3px}[hidden]{display:none!important}
.round2-loading{display:none;max-width:1100px;margin:30px auto;padding:28px;border:1px solid var(--line);border-radius:14px;background:#fff;color:var(--muted)}.round2-booting #round2-loading{display:block}.round2-booting #round2-public-preview{display:none}
/* Unified top navigation, mirroring the first-round app header (offline.css compact-topbar). */
.topbar{height:72px;display:flex;align-items:center;gap:24px;padding:0 max(24px,calc((100vw - 1440px)/2));background:rgba(255,255,255,.96);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:30;backdrop-filter:blur(14px)}.brand{display:inline-flex;align-items:center;flex-shrink:0}.brand-logo{display:block}.prep-context{flex:1;min-width:0;display:flex;align-items:center;justify-content:flex-start;gap:28px;flex-direction:row}.prep-goal-label{display:flex;align-items:center;flex-shrink:0}.prep-context select{border:1px solid #e2e8f0;border-radius:8px;background:#f7f9fc;padding:9px 24px 9px 12px;font-size:13px;font-weight:800;color:#102d50;cursor:pointer}.prep-context nav{display:flex;gap:20px;flex-wrap:nowrap;white-space:nowrap;align-items:center;flex:0 1 auto}.prep-context nav a{color:#64748b;font-size:13px;font-weight:700;padding:25px 0 23px;border-bottom:3px solid transparent}.prep-context nav a:hover{color:#1d4fbd}.prep-context nav a[aria-current="page"]{color:#1d4fbd;border-bottom-color:var(--blue)}
/* Account area, mirroring the first-round app header (offline.css account-menu). */
.account-menu{display:flex;align-items:center;gap:7px;flex-shrink:0;margin-left:auto}.account-menu button,.account-menu>a{border:1px solid var(--line);background:#fff;color:#536276;border-radius:9px;padding:7px 10px;cursor:pointer;font-size:12px;font-weight:800;text-decoration:none}.account-menu button:hover,.account-menu>a:hover{color:#102d50}.account-menu .login-entry{margin-right:7px}.account-menu .account-primary{background:var(--blue);color:#fff;border-color:var(--blue)}.account-menu .account-primary:hover{background:#2457bd;color:#fff}.account-divider{width:1px;height:14px;background:#e1e6ed}.account-dropdown-wrap{position:relative}.account-menu button.account-name{display:flex;align-items:center;gap:6px;max-width:140px;padding:7px 5px;background:transparent;font-size:13px;font-weight:400;border:0;white-space:nowrap}.account-name span{display:block;overflow:hidden;text-overflow:ellipsis}.account-name .account-chevron{display:block;align-self:center;color:#8692a2;flex:0 0 12px;width:12px;height:12px}.account-menu button.account-name:hover,.account-menu button.account-name[aria-expanded="true"]{background:#f1f4f8}.account-dropdown{position:absolute;top:calc(100% + 8px);right:0;min-width:148px;padding:5px;background:#fff;border:1px solid #e2e7ee;border-radius:12px;box-shadow:0 10px 35px #263d5826;z-index:110}.account-dropdown button{display:block;width:100%;text-align:left;border:0;background:#fff;color:var(--ink);padding:10px 12px;font-size:13px;font-weight:400;border-radius:7px}.account-dropdown button:hover{background:#f1f5fa;color:#2464b5}
/* Site-message envelope and dialog, same look as the first-round app (offline.css). */
.account-menu .website-updates-entry{position:relative;display:inline-flex;align-items:center;justify-content:center;flex:0 0 40px;width:40px;height:40px;border:0;padding:0;background:transparent;color:#596779}.message-envelope{display:block;flex-shrink:0;transform:translateY(1px)}.account-menu .updates-dot{transform:translateY(1px)}.account-menu .website-updates-entry:hover{color:var(--blue)}.updates-dot{position:absolute;top:8px;right:7px;width:6px;height:6px;border-radius:50%;background:#e36b5d;box-shadow:0 0 0 2px #fff;pointer-events:none}.auth-overlay{position:fixed;inset:0;z-index:100;display:grid;place-items:center;padding:20px;background:rgba(9,28,51,.46);backdrop-filter:blur(6px)}.website-updates-card{width:min(560px,calc(100vw - 32px));max-height:calc(100dvh - 64px);display:flex;flex-direction:column;border:1px solid #e3e8ef;background:#fff;border-radius:18px;box-shadow:0 24px 80px #10243b33;overflow:hidden}.website-updates-heading{display:flex;align-items:flex-start;justify-content:space-between;padding:25px 28px 18px;border-bottom:1px solid #edf0f4}.website-updates-heading h2{margin:0;font-size:21px;font-weight:600;color:#25364a}.updates-close{background:transparent;border:0;color:#8390a0;width:30px;height:30px;font-size:25px;cursor:pointer;border-radius:6px}.updates-close:hover{background:#f1f4f8}.website-updates-list{overflow-y:auto;padding:0 28px}.website-update-item{padding:23px 0}.website-update-item+.website-update-item{border-top:1px solid #edf0f4}.website-update-item time{font-size:12px;color:#8895a5}.website-update-item h3{margin:8px 0 10px;color:#34465c;font-size:16px;line-height:1.6;font-weight:500}.website-update-item p{margin:0 0 13px;font-size:14px;line-height:1.8;color:#69788a}.update-action,.updates-retry,.updates-read-error button{border:0;background:transparent;color:#3274b9;padding:3px 0;cursor:pointer;font-size:13px;text-decoration:none}.update-action:hover{text-decoration:underline}.updates-state{padding:20px 0;color:#748195;font-size:14px}.updates-retry{margin-bottom:20px}.updates-read-error{margin:0;padding:12px 28px 16px;font-size:13px;color:#b34545;border-top:1px solid #edf0f4}@media(max-width:480px){.auth-overlay{padding:12px}}main{max-width:1468px;margin:auto;padding:32px 24px}.hero{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-bottom:26px}.eyebrow{color:var(--blue);font-size:12px;font-weight:700;letter-spacing:1px;margin:0 0 5px}h1{font-size:30px;line-height:1.4;letter-spacing:-.7px;margin:0}h2{font-size:19px;margin:0}.hero p:last-child{margin:7px 0 0}.muted{color:var(--muted)}.small{font-size:12px}.engine{font-size:12px;background:#fff;border:1px solid var(--line);border-radius:24px;padding:9px 15px}.engine.ready{color:var(--green);background:#eefaf4;border-color:#c6ebd9}.problem-tabs{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin-bottom:22px}.problem-tab{text-align:left;border:1px solid var(--line);background:#fff;border-radius:12px;padding:15px 18px;color:var(--ink)}.problem-tab strong{display:block;font-size:16px}.problem-tab span{font-size:12px;color:var(--muted)}.problem-tab.active{border-color:var(--blue);background:#eff5ff;box-shadow:inset 0 0 0 1px var(--blue)}.problem-tab.active strong{color:var(--blue)}.workspace{display:grid;grid-template-columns:minmax(0,1.12fr) minmax(380px,1fr);gap:22px;align-items:start}.statement-card,.editor-card,.result-card,.history-card{background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden}.statement-card{padding:26px 30px}.statement-heading{display:flex;justify-content:space-between;gap:12px;align-items:center;padding-bottom:16px}.statement-heading h2{font-size:26px}.statement-heading a{font-size:12px;white-space:nowrap}.limits{border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:12px 0;color:var(--muted);font-size:12px;margin-bottom:22px}.statement{overflow-wrap:anywhere;line-height:1.95}.statement h1{display:none}.statement h2{font-size:18px;margin:26px 0 10px}.statement h3{font-size:15px;margin:22px 0 8px}.statement p{margin:12px 0}.statement img{display:block;max-width:100%;max-height:400px;height:auto;object-fit:contain;margin:16px auto}.statement pre{background:#f5f7fb;border:1px solid #e6ecf3;border-radius:8px;padding:14px 16px;overflow:auto;font:13px/1.65 Consolas,monospace}.statement code{font-family:Consolas,monospace}.statement table{border-collapse:collapse;width:100%;font-size:13px;margin:12px 0}.statement td,.statement th{border:1px solid var(--line);padding:7px 10px;text-align:center}.statement th{background:#f5f7fb}.statement .katex{font-size:1.05em}.statement .katex-display{overflow-x:auto;overflow-y:hidden}.coding-panel{display:grid;gap:18px}.editor-card,.result-card,.history-card{padding:20px}.section-heading{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:14px}.section-heading h2{font-size:16px}.section-heading>span{color:var(--muted);font-size:11px}.editor-toolbar{display:flex;align-items:center;gap:12px;font-size:12px}.editor-toolbar select{min-width:0;flex:1;border:1px solid var(--line);border-radius:7px;padding:7px;background:#fff;color:var(--ink)}#io-help{margin:7px 0 12px}#code{display:block;resize:none;min-height:220px;height:440px;width:100%;border:1px solid #233650;border-radius:9px 9px 0 0;background:#142235;color:#e3efff;padding:17px 18px;font:13px/1.8 Consolas,"Cascadia Code",monospace;tab-size:4;white-space:pre;overflow:auto;outline-color:#6495f2}.editor-footer{display:flex;justify-content:space-between;gap:8px;color:var(--muted);font-size:11px;margin-top:8px}.submit-actions{display:flex;gap:10px;margin-top:17px}.primary,.secondary{border-radius:8px;padding:10px 16px;font-size:13px;font-weight:700}.primary{background:var(--blue);color:#fff;border:1px solid var(--blue);flex:1}.secondary{background:#fff;color:var(--blue);border:1px solid #c9dafb}.text-button{background:none;border:0;color:var(--blue);font-size:12px}.empty{font-size:13px;color:var(--muted);padding:10px 0;margin:0}.result-summary{display:flex;align-items:center;gap:10px;margin:6px 0 14px}.result-summary strong{font-size:23px}.badge{display:inline-block;font-size:11px;font-weight:700;border-radius:5px;padding:2px 7px;background:#edf2fa;color:#52657d}.badge.AC{color:#087449;background:#e1f5ea}.badge.WA,.badge.CE,.badge.RE,.badge.TLE,.badge.MLE,.badge.OLE,.badge.SYSTEM_ERROR{color:#b34b29;background:#fff0e9}.cases{display:grid;grid-template-columns:repeat(auto-fill,minmax(67px,1fr));gap:7px}.case{border:1px solid var(--line);border-radius:7px;text-align:center;padding:7px 4px;cursor:pointer;background:#fff;color:var(--ink)}.case strong{display:block;font-size:12px}.case small{display:block;color:var(--muted);font-size:10px}.case.AC{background:#f1faf5;border-color:#cce9db}.case.WA,.case.TLE,.case.RE,.case.MLE,.case.OLE{background:#fff6f0;border-color:#f0d3c1}.case.pending{opacity:.5}.result-log{white-space:pre-wrap;overflow-wrap:anywhere;max-height:220px;overflow:auto;background:#f7f8fb;padding:12px;font:12px/1.7 Consolas,monospace;border-radius:8px}.history-row{width:100%;display:flex;align-items:center;gap:10px;padding:11px 0;border:0;border-top:1px solid #eef1f6;background:transparent;text-align:left;color:var(--ink);font-size:12px}.history-row.selected{color:var(--blue)}.history-row time{margin-left:auto;color:var(--muted);font-size:11px}.sample-downloads{border-top:1px solid var(--line);padding-top:15px;margin-top:24px;font-size:12px}.sample-downloads a.sample-zip{display:block;width:fit-content;padding:7px 14px;border:1px solid #c9dafb;border-radius:8px;background:#eff5ff;color:var(--blue);font-weight:700;text-decoration:none}.sample-downloads a.sample-zip:hover{background:#e3eeff;border-color:var(--blue)}.notice{background:#fff4e8;border:1px solid #f1d6ac;color:#83510d;padding:12px 16px;border-radius:10px;font-size:13px;margin-bottom:18px}.login-panel{max-width:420px;margin:45px auto;background:#fff;padding:28px;border:1px solid var(--line);border-radius:14px}.login-panel label{display:block;font-size:13px;margin:15px 0}.login-panel input{display:block;width:100%;border:1px solid var(--line);border-radius:6px;padding:9px}.login-panel button{width:100%}#login-error{color:#b34b29;font-size:13px}footer{text-align:center;font-size:11px;color:#8995a7;margin-top:30px}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0)}@media(min-width:1600px){.coding-panel{position:sticky;top:18px}}@media(max-width:950px){.workspace{grid-template-columns:1fr}.coding-panel{position:static}.hero{align-items:start}.statement-card{padding:22px}.problem-tab{padding:12px}.problem-tab strong{font-size:14px}}@media(max-width:1200px){.topbar{gap:18px;padding:0 20px}.prep-context{gap:20px}.prep-context nav{gap:14px}.prep-context nav a{font-size:12px}}@media(max-width:520px){main{padding:22px 14px}.topbar{gap:14px;padding:0 14px;flex-wrap:wrap;height:auto;min-height:56px}.prep-context{gap:12px;flex-wrap:wrap}.prep-context nav a{padding:10px 0;border-bottom-width:2px}.hero{display:block}.engine{display:inline-block;margin-top:14px}.problem-tabs{grid-template-columns:repeat(2,1fr);gap:8px}.statement-card{padding:18px}.statement-heading a{font-size:11px}.editor-card,.result-card,.history-card{padding:16px}.statement table{font-size:11px}.statement td,.statement th{padding:5px}h1{font-size:26px}}

/* Reading is the default; the workspace expands only on request. */
.workspace{grid-template-columns:minmax(0,1fr);max-width:960px;margin-inline:auto}.workspace.is-coding{max-width:none;grid-template-columns:minmax(0,1.12fr) minmax(380px,1fr)}.coding-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:0 4px;font-size:13px;color:var(--muted)}#open-code{flex:none;white-space:nowrap}.statement-heading{flex-wrap:wrap}@media(max-width:950px){.workspace.is-coding{grid-template-columns:minmax(0,1fr)}}

.paper-overview{max-width:1040px;margin:0 auto}.paper-summary{display:flex;gap:44px;align-items:center;padding:28px 32px;border:1px solid #d6e3fb;border-radius:16px;background:linear-gradient(115deg,#edf4ff,#fff 80%);margin-bottom:32px}.paper-score{display:flex;align-items:baseline;gap:10px}.paper-score strong{font-size:40px;line-height:1.25;letter-spacing:-1px}.paper-score span,.paper-completion span{color:var(--muted);font-size:13px}.paper-summary p{margin:4px 0}.paper-completion{display:flex;flex-direction:column;border-left:1px solid #d5e0ee;padding-left:36px}.paper-completion strong{font-size:24px}.paper-summary>.primary{flex:none;margin-left:auto}.paper-list-heading{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:14px}.paper-list-meta{display:flex;align-items:center;gap:10px}.paper-list-meta>span{font-size:12px;color:var(--muted)}.algorithm-tags-toggle{border:1px solid #c9dafb;border-radius:16px;padding:4px 10px;background:#fff;color:var(--blue);font-size:12px;font-weight:700}.algorithm-tags-toggle:hover{background:#f3f7ff}.algorithm-tags-toggle[aria-pressed="true"]{background:#eef4ff;border-color:#a9c7fa}.paper-list{background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden}.paper-row{display:grid;grid-template-columns:46px minmax(0,1fr) 180px 140px;align-items:center;gap:20px;padding:25px 28px}.paper-row+.paper-row{border-top:1px solid var(--line)}.paper-number{font:600 20px/1.4 Consolas,monospace;color:#8b9bb2}.paper-title h3{font-size:18px;margin:0 0 4px}.paper-title p{font-size:12px;color:var(--muted);margin:0}.paper-progress{display:flex;flex-direction:column;gap:5px}.paper-progress strong{font-size:15px}.paper-progress small{font-size:11px;color:var(--muted)}.paper-progress.solved strong{color:var(--green)}.score-track{width:120px;height:4px;border-radius:9px;overflow:hidden;background:#edf1f7}.score-track i{display:block;height:100%;background:var(--blue)}.solved .score-track i{background:var(--green)}.paper-row>button{white-space:nowrap}.paper-note{font-size:12px;text-align:center;color:var(--muted);margin:20px 0}.paper-breadcrumb{display:flex;align-items:center;justify-content:space-between;max-width:960px;margin:0 auto 15px}.paper-breadcrumb button{padding:5px 0;font-size:13px}.paper-breadcrumb span{font-size:12px;color:var(--muted)}#workspace>.problem-tabs{max-width:960px;margin-inline:auto;gap:8px}#workspace .problem-tab{padding:10px 14px}#workspace .problem-tab strong{font-size:14px}#workspace .problem-tab span{font-size:11px}.question-actions{display:flex;gap:12px;border-top:1px solid var(--line);margin-top:24px;padding-top:20px}.question-actions .primary{flex:none}.paper-algorithm-tags{display:none}.show-algorithm-tags .paper-algorithm-tags{display:inline}@media(max-width:650px){.paper-summary{padding:22px;gap:20px;flex-wrap:wrap}.paper-summary>.primary{width:100%;margin:0}.paper-completion{padding-left:24px}.paper-row{grid-template-columns:28px minmax(0,1fr) auto;gap:12px;padding:20px 16px}.paper-progress{grid-column:2;grid-row:auto}.paper-row>button{grid-column:3;grid-row:1 / span 2;padding:9px 12px}.paper-number{font-size:17px}.paper-title h3{font-size:16px}.paper-list-meta>span{font-size:11px}.paper-note{text-align:left}.question-actions{flex-wrap:wrap}.question-actions button{flex:1!important}}

/* Shared breadcrumb styling for papers and individual problems. */
#paper-hero{max-width:1040px;margin-inline:auto}.paper-location{display:flex;align-items:center;flex-wrap:wrap;gap:6px 12px;list-style:none;margin:0;padding:0;min-width:0}.paper-location li{display:flex;align-items:center;gap:12px}.paper-location li+li::before{content:"/";color:#b1bdcb}.paper-location a{font-size:13px}.paper-location a:hover{text-decoration:underline}.paper-location [aria-current="page"]{color:var(--ink);font-size:13px}.paper-breadcrumb{gap:12px;flex-wrap:wrap}#question-position{white-space:nowrap;margin-left:auto}.paper-breadcrumb .breadcrumb-divider{color:#b1bdcb}.statement-heading h1,.statement-heading h2{font-size:26px;line-height:1.4;letter-spacing:0}.statement-heading{min-height:58px}#workspace.is-coding>.paper-breadcrumb,#workspace.is-coding>.problem-tabs{max-width:none}@media(max-width:520px){.paper-location{gap:4px 8px}.paper-location li{gap:8px}.statement-heading h1,.statement-heading h2{font-size:23px}.paper-breadcrumb{gap:12px}.paper-breadcrumb span{font-size:11px}}
/* Match the first-round paper return action while keeping one navigation row. */
.paper-location .paper-catalog-back{display:inline-block;border-radius:10px;padding:11px 13px;background:var(--blue);color:#fff;font-size:13px;font-weight:850;text-decoration:none}.paper-location .paper-catalog-back:hover{background:#2457bd;text-decoration:none}

/* Knowledge-point practice: first-round-style knowledge tree, difficulty chips and problem rows. */
.topics-overview{max-width:1240px;margin:0 auto}.topics-layout{display:grid;grid-template-columns:264px minmax(0,1fr);gap:22px;align-items:start}.topic-nav{background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px;position:sticky;top:18px;max-height:calc(100vh - 36px);overflow:auto}.tree-heading{padding:2px 6px 12px}.tree-heading span{display:block;color:var(--blue);font-size:12px;font-weight:700}.tree-heading h2{font-size:18px;margin:2px 0}.tree-heading p{font-size:12px;color:var(--muted);margin:0}.topic-heading{display:flex;align-items:center;justify-content:space-between;gap:8px;padding:10px 6px 8px;font-size:13px;font-weight:700}.topic-heading b{margin-left:6px;color:var(--blue);font-weight:700}.topic-multi-toggle{border:1px solid #c9dafb;background:#fff;color:var(--blue);border-radius:14px;padding:3px 12px;font-size:12px;font-weight:700}.topic-multi-toggle.active{background:var(--blue);border-color:var(--blue);color:#fff}.topic-link{display:flex;align-items:center;justify-content:space-between;gap:8px;width:100%;text-align:left;background:transparent;border:0;border-radius:9px;padding:8px 10px;color:var(--ink);font-size:13.5px;line-height:1.4}.topic-link > span{display:flex;align-items:center;gap:7px;min-width:0}.topic-link:hover{background:#f3f7ff}.topic-link.selected{background:#eff5ff;box-shadow:inset 0 0 0 1px var(--blue);color:var(--blue);font-weight:700}.topic-count{flex:none;font-size:11px;color:var(--muted);white-space:nowrap}.topic-count b{color:var(--ink);font-size:12px}.topic-count span{display:inline}.topic-tree{margin-top:4px}.topic-tree h3{font-size:11px;color:#8b9bb2;margin:12px 6px 5px;font-weight:700}.topic-check{display:inline-flex;align-items:center;justify-content:center;width:15px;height:15px;flex:none;border:1px solid #b9c8dd;border-radius:4px;font-size:11px;font-style:normal;color:var(--blue);background:#fff}.topic-toolbar{display:flex;align-items:center;gap:14px;flex-wrap:wrap;margin-bottom:14px}.difficulty-filter{display:flex;gap:8px;flex-wrap:wrap}.diff-chip{border:1px solid #c9dafb;background:#fff;color:var(--blue);border-radius:20px;padding:5px 13px;font-size:12px;font-weight:700}.diff-chip small{font-weight:400;color:var(--muted);margin-left:3px}.diff-chip:hover{background:#f3f7ff}.diff-chip.active{background:var(--blue);border-color:var(--blue);color:#fff}.diff-chip.active small{color:#d7e5ff}.diff-chip.none{opacity:.45;cursor:default}.topic-main{min-width:0}.topics-list{background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden}.topic-problem{display:flex;flex-direction:column;gap:2px;padding:12px 22px;color:var(--ink)}.topic-problem+.topic-problem{border-top:1px solid #eef1f6}.topic-problem:hover{background:#f6f9ff}.topic-problem.solved .tp-title{color:var(--green)}.tp-main{display:flex;align-items:center;gap:10px;flex-wrap:wrap}.tp-year{font:600 13px/1.4 Consolas,monospace;color:#8b9bb2;min-width:38px}.tp-title{font-size:14px;font-weight:700}.tp-diff{font-size:11px;color:#7a5fb0;background:#f1edfa;border-radius:5px;padding:2px 7px}.tp-state{margin-left:auto;font-size:12px;color:var(--muted);white-space:nowrap}.tp-note{font-size:12px;color:var(--muted);padding-left:48px}.ktag{display:inline-block;font-size:11px;line-height:1.6;color:#31548f;background:#eef4ff;border:1px solid #d6e3fb;border-radius:5px;padding:1px 7px;margin:2px 6px 0 0}.ktag.diff{color:#7a5fb0;background:#f6f2fc;border-color:#e2d6f5}.paper-tags{margin:6px 0 0}.problem-tags{margin:-14px 0 18px}.knowledge-note{margin-top:8px}@media(max-width:950px){.topics-layout{grid-template-columns:1fr;gap:14px}.topic-nav{position:static;max-height:none;padding:10px}.tree-heading,.topic-tree h3{display:none}.topic-heading{padding-top:0}.topic-tree{display:flex;gap:4px;overflow-x:auto}.topic-tree section{display:contents}.topic-tree .topic-link{flex:none;white-space:nowrap}}@media(max-width:650px){.topic-problem{padding:11px 16px}.tp-note{padding-left:0}.tp-state{margin-left:0;width:100%}}

/* A viewport-sized coding workspace; reading retains its comfortable line length. */
.workspace-splitter{position:relative;align-self:stretch;cursor:col-resize;touch-action:none;border-radius:6px;outline-offset:-2px}
.workspace-splitter::before{content:"";position:absolute;top:0;bottom:0;left:5px;width:2px;background:#dce5f1;border-radius:2px}
.workspace-splitter::after{content:"";position:absolute;top:50%;left:3px;width:6px;height:40px;transform:translateY(-50%);border-radius:4px;background:#b6c7de}
.workspace-splitter:hover::after,.workspace-splitter:focus-visible::after,.resizing-workspace .workspace-splitter::after{background:var(--blue)}
.workspace-splitter:focus-visible{outline:2px solid var(--blue)}
.resizing-workspace,.resizing-workspace *{cursor:col-resize!important;user-select:none!important}
.evaluation-panel{min-width:0;border:1px solid var(--line);border-radius:12px;background:#fff;overflow:hidden}
.evaluation-panel>summary{display:flex;align-items:center;gap:10px;padding:11px 16px;list-style:none;font-size:13px;font-weight:700;cursor:pointer}
.evaluation-panel>summary::-webkit-details-marker{display:none}
.evaluation-panel>summary::before{content:"›";font-size:20px;line-height:1;transition:transform .15s}
.evaluation-panel[open]>summary::before{transform:rotate(90deg)}
.evaluation-panel>summary::after{content:"展开";flex:none;color:var(--blue);font-size:12px;font-weight:400}
.evaluation-panel[open]>summary::after{content:"收起"}
.evaluation-panel>summary:focus-visible{outline:2px solid var(--blue);outline-offset:-3px}
#evaluation-status{margin-left:auto;font-size:12px;font-weight:400;color:var(--muted);text-align:right}
.evaluation-scroll{min-height:0;overflow:auto;overscroll-behavior:contain;border-top:1px solid var(--line)}
.evaluation-scroll .result-card,.evaluation-scroll .history-card{border:0;border-radius:0}
.evaluation-scroll .history-card{border-top:1px solid var(--line)}
body.coding-desktop{position:fixed;inset:0;width:100%;height:100dvh;overflow:hidden;display:flex;flex-direction:column}
.coding-desktop .topbar{flex:none;padding-inline:24px}
.coding-desktop main{width:100%;max-width:none;margin:0;padding:12px 24px 16px;flex:1;min-height:0;display:flex;flex-direction:column}
.coding-desktop main>footer{display:none}
.coding-desktop main>.notice{flex:none;max-height:64px;overflow:auto;margin-bottom:8px}
.coding-desktop #workspace{flex:1;min-height:0;display:flex;flex-direction:column}
.coding-desktop #workspace>.paper-breadcrumb{width:100%;flex:none;margin-bottom:10px}
.coding-desktop .paper-catalog-back{padding:6px 10px}
.coding-desktop #workspace>.problem-tabs{width:100%;flex:none;margin:0 0 12px}
.coding-desktop #workspace .problem-tab{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:7px 12px}
.coding-desktop #workspace .problem-tab strong{min-width:0;overflow:hidden;white-space:nowrap;text-overflow:ellipsis}
.coding-desktop #workspace .problem-tab span{flex:none}
.coding-desktop .workspace.is-coding{width:100%;flex:1;min-height:0;grid-template-columns:minmax(0,var(--statement-fr,45fr)) 12px minmax(0,var(--editor-fr,55fr));gap:0;align-items:stretch}
.coding-desktop .statement-card{min-width:0;min-height:0;overflow:auto;overscroll-behavior:contain;scrollbar-gutter:stable;padding:20px 24px}
.coding-desktop .coding-panel{position:static;min-width:0;min-height:0;display:flex;flex-direction:column;gap:10px;overflow:auto;overscroll-behavior:contain;scrollbar-gutter:stable}
.coding-desktop .coding-heading{flex:none;padding:0 4px;min-height:24px}
.coding-desktop #close-code{display:none}
.coding-desktop .editor-card{flex:none;min-height:0;display:flex;flex-direction:column;padding:14px 16px;overflow:visible}
.coding-desktop .editor-card>.section-heading{flex:none;margin-bottom:8px}
.coding-desktop .editor-toolbar{flex:none}
.coding-desktop #io-help{flex:none;margin:5px 0 8px}
.coding-desktop #code{flex:none;min-height:220px;height:max(400px,calc(100dvh - 380px));resize:none;font-size:14px;padding:14px 16px}
.coding-desktop .editor-footer{flex:none;margin-top:6px}
.coding-desktop .submit-actions{flex:none;position:sticky;bottom:0;z-index:2;margin-top:4px;padding-block:8px;background:#fff}
.coding-desktop #scoring-help{flex:none;margin:6px 0 0;font-size:11px}
.coding-desktop #judge-availability{flex:none;margin:6px 0 0}
.coding-desktop .evaluation-panel{flex:none}
.coding-desktop .evaluation-scroll{max-height:none;overflow:visible}
.coding-desktop .evaluation-panel>summary{padding:8px 14px}
.coding-desktop .evaluation-scroll .result-card,.coding-desktop .evaluation-scroll .history-card{padding:14px 16px}
/* Keep feedback clear of both scroll panes and their controls. */
.coding-desktop #r2-feedback-open{position:static;inset:auto;min-width:0;width:auto;height:auto;padding:0 6px;margin-left:auto;border:0;border-radius:4px;box-shadow:none;background:transparent;font-size:12px;font-weight:400;line-height:1.7}
@media(max-width:950px),(max-height:699px){
  .workspace.is-coding{grid-template-columns:minmax(0,1fr)}
  .coding-panel{position:static}
  .editor-card{overflow:visible}
  .submit-actions{position:sticky;bottom:0;z-index:2;padding-block:10px;background:#fff}
  .evaluation-scroll{max-height:55dvh}
}

.code-resizer{position:relative;flex:none;height:16px;width:100%;margin-top:-1px;background:#142235;border:1px solid #233650;border-top:0;border-radius:0 0 9px 9px;cursor:ns-resize;touch-action:none;user-select:none}
.code-resizer::after{content:"";position:absolute;left:50%;top:5px;width:42px;height:4px;transform:translateX(-50%);border-radius:3px;background:#7c93b1}
.code-resizer:hover::after,.code-resizer:focus-visible::after,.resizing-code .code-resizer::after{background:#adcaff}
.code-resizer:focus-visible{outline:2px solid var(--blue);outline-offset:2px}
.resizing-code,.resizing-code *{cursor:ns-resize!important;user-select:none!important}
.resizing-code .coding-panel{overflow-anchor:none}
.editor-card #code{padding:0;overflow:hidden}
.coding-desktop .editor-card #code{padding:0}
#code .cm-editor{height:100%;border-radius:8px 8px 0 0}
#code .cm-scroller{overflow:auto;padding:8px 0}
#code .cm-content{padding-inline:4px}
#code .cm-focused{outline:2px solid #6495f2;outline-offset:-2px}
#code .cm-tooltip-autocomplete > ul > li[aria-selected]{background:#2457bd;color:#fff;box-shadow:inset 3px 0 #b8d3ff}
#code .cm-tooltip-autocomplete > ul > li[aria-selected] .cm-completionDetail{color:#eaf2ff}
.tp-position{font-size:11px;color:#718198;white-space:nowrap}

@media(max-width:520px){.topbar{display:grid;grid-template-columns:auto 1fr auto;gap:4px 12px;padding:8px 14px}.topbar .brand{grid-column:1;grid-row:1}.topbar .account-menu{grid-column:3;grid-row:1;margin-left:0}.topbar .prep-context{grid-column:1/-1;grid-row:2;flex-direction:column;align-items:stretch;gap:4px;padding-bottom:3px}.topbar .prep-context nav{width:100%;justify-content:space-between;gap:8px}.topbar .prep-context nav a{font-size:11px;padding:8px 0 6px}}

.paper-answer-note{margin:4px 0 0;color:var(--muted);font-size:13px;line-height:1.6}

#paper-hero .paper-catalog-back{padding:7px 12px;border:1px solid #cdddf5;border-radius:8px;background:#edf4ff;color:#2457bd;font-size:13px;font-weight:700}#paper-hero .paper-catalog-back:hover{background:#e0ecff;border-color:#a9c7ef;color:#1d4fbd}
/* Notes occupy their own reading tab between the statement and editorial. */
.problem-notes { padding:8px 0; }
.problem-notes h2 { font-size:18px; margin:0 0 12px; }
.note-body { padding:0; }
.note-body p { margin:12px 0 0; }
#note-content { display:block; box-sizing:border-box; width:100%; min-height:160px; padding:12px; border:1px solid #cbd5e1; border-radius:8px; background:white; color:#1e293b; font:inherit; font-size:15px; line-height:1.7; resize:vertical; }
#note-content:focus { outline:2px solid #bfdbfe; border-color:#3b82f6; }
#note-content:disabled { background:#f1f5f9; }
.note-footer { display:flex; align-items:center; flex-wrap:wrap; gap:12px; margin-top:10px; font-size:13px; color:#64748b; }
#note-count { margin-left:auto; }
.note-footer button[hidden] { display:none; }
.note-footer .note-error { color:#b45309; }
dialog.login-panel { position:fixed; inset:0; margin:auto; width:calc(100% - 32px); max-height:calc(100dvh - 40px); overflow:auto; box-shadow:0 20px 70px #0f172a33; }
dialog.login-panel::backdrop { background:#0f172a66; }