:root{--bg:#f5f5f5;--surface:#fff;--border:#e2e2e2;--text:#1a1a2e;--text2:#6b7280;--accent:#7c3aed;--accent2:#a78bfa;--accent-light:#7c3aed14;--easy:#059669;--easy-bg:#d1fae5;--medium:#d97706;--medium-bg:#fef3c7;--hard:#dc2626;--hard-bg:#fee2e2;--hover:#f3f4f6;--shadow:#0000000f;--code-bg:#1e1e2e;--code-text:#cdd6f4;--output-bg:#111;--output-header:#1a1a2e;--output-text:#a6e3a1}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--bg);color:var(--text);height:100vh;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;overflow:hidden}#root{height:100%}.app{flex-direction:column;height:100%;display:flex}header{background:var(--surface);border-bottom:1px solid var(--border);flex-shrink:0;align-items:center;gap:12px;padding:8px 16px;display:flex}.header-left{align-items:center;gap:8px;display:flex}.brand{flex-shrink:0;align-items:center;gap:8px;display:flex}.logo-icon{flex-shrink:0;height:30px;display:block}.brand-name{color:var(--text);font-size:16px;font-weight:700;display:none}@media (width>=640px){.brand-name{display:inline}}.badge{background:var(--hover);color:var(--text2);border-radius:10px;padding:2px 8px;font-size:11px}.solved-badge{background:var(--easy);color:#fff}.view-tabs{background:var(--hover);border-radius:8px;gap:2px;margin-right:4px;padding:2px;display:flex}.view-tab{cursor:pointer;color:var(--text2);background:0 0;border:none;border-radius:6px;padding:4px 12px;font-size:12px;font-weight:500;transition:all .15s}.view-tab.active{background:var(--surface);color:var(--accent);box-shadow:0 1px 3px var(--shadow)}.view-tab:hover:not(.active){color:var(--text)}.interview-subtitle{color:var(--text2);font-size:13px;font-weight:500}.header-center{flex:1;max-width:400px}.search{border:1px solid var(--border);background:var(--bg);width:100%;color:var(--text);border-radius:6px;outline:none;padding:6px 12px;font-size:13px;transition:border-color .15s}.search:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-light)}.header-right{align-items:center;gap:6px;display:flex}.header-right select{border:1px solid var(--border);background:var(--bg);color:var(--text);cursor:pointer;border-radius:5px;outline:none;padding:5px 8px;font-size:12px;transition:border-color .15s}.header-right select:focus{border-color:var(--accent)}.main{flex:1;display:flex;overflow:hidden}.problem-sidebar{background:var(--surface);border-right:1px solid var(--border);flex-direction:column;width:300px;min-width:300px;display:flex;overflow:hidden}.list-header{color:var(--text2);border-bottom:1px solid var(--border);flex-shrink:0;padding:8px 12px;font-size:12px}.problem-list{flex:1;overflow-y:auto}.problem-item{cursor:pointer;border-bottom:1px solid var(--border);align-items:center;gap:6px;padding:8px 12px;font-size:13px;transition:background .1s;display:flex}.problem-item:hover{background:var(--hover)}.problem-item.active{background:var(--accent-light);border-left:3px solid var(--accent)}.status{width:16px;color:var(--text2);flex-shrink:0;font-size:12px}.status.solved{color:var(--easy)}.pnum{color:var(--text2);flex-shrink:0;min-width:24px}.ptitle{white-space:nowrap;text-overflow:ellipsis;flex:1;overflow:hidden}.pdiff{text-transform:uppercase;border-radius:4px;flex-shrink:0;padding:1px 6px;font-size:10px;font-weight:600}.pdiff.easy{background:var(--easy-bg);color:var(--easy)}.pdiff.medium{background:var(--medium-bg);color:var(--medium)}.pdiff.hard{background:var(--hard-bg);color:var(--hard)}section{flex-direction:column;flex:1;display:flex;overflow:hidden}.split-view{flex:1;display:flex;overflow:hidden}.editor-panel{background:var(--surface);flex-direction:column;width:50%;min-width:400px;display:flex}.split-view>.editor-panel{border-left:1px solid var(--border)}.editor-header{background:var(--surface);border-bottom:1px solid var(--border);flex-shrink:0;justify-content:space-between;align-items:center;padding:8px 14px;font-size:13px;display:flex}.editor-actions{gap:6px;display:flex}.solution-btn{color:var(--accent);border:1px solid var(--accent);cursor:pointer;background:0 0;border-radius:5px;padding:5px 12px;font-size:12px}.solution-btn:hover{background:var(--accent);color:#fff}.run-btn{background:var(--accent);color:#fff;cursor:pointer;border:none;border-radius:5px;padding:5px 16px;font-size:12px}.run-btn:hover{background:var(--accent2)}.code-editor{resize:none;background:var(--code-bg);color:var(--code-text);tab-size:2;caret-color:var(--accent);border:none;outline:none;flex:1;padding:16px;font-family:JetBrains Mono,Fira Code,monospace;font-size:14px;line-height:1.7}.output{background:var(--output-bg);border-top:1px solid var(--border);flex-shrink:0;max-height:160px;overflow-y:auto}.output-header{color:var(--accent);background:var(--output-header);border-bottom:1px solid var(--border);padding:6px 14px;font-size:12px;position:sticky;top:0}.output pre{color:var(--output-text);white-space:pre-wrap;margin:0;padding:10px 14px;font-size:12px}.problem-panel{background:var(--bg);flex:1;padding:20px 24px;overflow-y:auto}.pv-header{flex-wrap:wrap;align-items:center;gap:8px;margin-bottom:16px;display:flex}.pv-header h2{font-size:18px}.pcat{color:var(--text2);background:var(--hover);border-radius:4px;padding:2px 8px;font-size:11px}.solved-btn{border:1px solid var(--border);cursor:pointer;color:var(--text2);background:0 0;border-radius:5px;margin-left:auto;padding:4px 10px;font-size:12px}.solved-btn.solved{background:var(--easy);color:#fff;border-color:var(--easy)}.pv-desc{margin-bottom:16px;font-size:14px;line-height:1.7}.pv-desc code{background:var(--hover);border:1px solid var(--border);border-radius:3px;padding:1px 5px;font-size:13px}.pv-examples{flex-direction:column;gap:10px;margin-bottom:16px;display:flex}.example{background:var(--surface);border:1px solid var(--border);border-radius:8px;padding:12px 16px;font-size:13px;line-height:1.7}.ex-label{color:var(--text2);margin-bottom:6px;font-size:12px;font-weight:600}.ex-title{color:var(--text2);font-size:12px}.example code{background:var(--hover);border-radius:3px;padding:1px 5px;font-family:JetBrains Mono,monospace;font-size:12px}.constraints{margin-top:8px}.constraints summary{cursor:pointer;color:var(--accent);font-size:13px;font-weight:500}.constraints ul{color:var(--text2);margin:10px 0 0 18px;font-size:12px;line-height:1.8}.empty{height:100%;color:var(--text2);justify-content:center;align-items:center;font-size:16px;display:flex}.interview-section{background:var(--bg);flex-direction:column;display:flex;overflow:hidden}.iprep{flex:1;max-width:900px;margin:0 auto;padding:24px 32px;overflow-y:auto}.iprep-list{flex-direction:column;gap:10px;display:flex}.iprep-card{border:1px solid var(--border);background:var(--surface);border-radius:10px;overflow:hidden}.iprep-card.expanded{border-color:var(--accent)}.iprep-header{text-align:left;cursor:pointer;width:100%;color:inherit;background:0 0;border:none;padding:16px 20px}.iprep-header:hover .iprep-title-row h3{color:var(--accent)}.iprep-meta{align-items:center;gap:8px;margin-bottom:6px;display:flex}.iprep-cat{color:var(--text2);background:var(--hover);border-radius:4px;padding:2px 8px;font-size:11px}.iprep-count{color:var(--accent);background:#6c5ce71a;border-radius:4px;margin-left:auto;padding:2px 8px;font-size:11px}.iprep-title-row{justify-content:space-between;align-items:center;gap:12px;display:flex}.iprep-title-row h3{margin:0;font-size:16px;font-weight:600;transition:color .15s}.iprep-chevron{color:var(--text2);font-size:12px}.iprep-desc{color:var(--text2);margin:6px 0 0;font-size:13px;line-height:1.4}.iprep-questions{border-top:1px solid var(--border)}.iprep-qa{border-bottom:1px solid var(--border)}.iprep-qa:last-child{border:none}.iprep-qheader{text-align:left;cursor:pointer;width:100%;color:var(--text);background:0 0;border:none;align-items:flex-start;gap:8px;padding:12px 20px 12px 28px;font-size:14px;font-weight:500;line-height:1.4;display:flex}.iprep-qheader:hover{background:var(--hover)}.iprep-qheader .iprep-chevron{flex-shrink:0;margin-top:3px;margin-left:auto}.iprep-qnum{color:var(--accent);flex-shrink:0;min-width:22px;font-weight:700}.iprep-qbody{padding:0 20px 16px 28px}.iprep-qbody p{margin:0 0 12px;font-size:14px;line-height:1.7}.iprep-code{background:var(--code-bg);border-radius:8px;margin-top:8px;overflow-x:auto}.iprep-code pre{margin:0;padding:14px}.iprep-code code{color:var(--code-text);white-space:pre;font-family:JetBrains Mono,monospace;font-size:13px;line-height:1.5}footer{background:var(--surface);border-top:1px solid var(--border);flex-shrink:0;justify-content:space-between;align-items:center;padding:10px 16px;display:flex}.footer-left{align-items:center;gap:8px;display:flex}.footer-right{align-items:center;display:flex}.footer-link{color:var(--text2);cursor:pointer;background:0 0;border:none;padding:2px 4px;font-size:13px;transition:color .15s}.footer-link:hover{color:var(--accent)}.footer-link.active{color:var(--accent);font-weight:500}.footer-dot{color:var(--border);font-size:12px}.visitor-count{color:var(--text2);font-size:12px}.mfe-loading{background:var(--bg);color:var(--text2);flex-direction:column;flex:1;justify-content:center;align-items:center;gap:12px;display:flex}.mfe-spinner{border:3px solid var(--border);border-top-color:var(--accent);border-radius:50%;width:32px;height:32px;animation:.7s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.static-page{background:var(--bg);flex:1;padding:40px 24px;overflow-y:auto}.static-card{background:var(--surface);border:1px solid var(--border);border-radius:12px;max-width:720px;margin:0 auto;padding:40px 48px}.static-card h1{color:var(--text);margin-bottom:20px;font-size:28px}.static-card h2{color:var(--text);margin:28px 0 10px;font-size:18px}.static-card p{color:var(--text2);margin-bottom:12px;font-size:15px;line-height:1.7}.static-card ul{color:var(--text2);margin:10px 0 0 20px;font-size:15px;line-height:1.8}.static-card a{color:var(--accent);text-decoration:none}.static-card a:hover{text-decoration:underline}.static-muted{color:var(--text2);margin-top:32px;font-size:13px}::-webkit-scrollbar{width:6px;height:6px}::-webkit-scrollbar-track{background:0 0}::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}::-webkit-scrollbar-thumb:hover{background:var(--text2)}*{scrollbar-width:thin;scrollbar-color:var(--border) transparent}@media (width<=1024px){.editor-panel{width:50%;min-width:0}.iprep{padding:20px}}@media (width<=900px){.split-view{flex-direction:column}.editor-panel{border-right:none;border-top:1px solid var(--border);flex:1;width:100%;min-width:0}.problem-panel{max-height:50%}.iprep{padding:16px}.iprep-qheader{padding:10px 16px 10px 20px;font-size:13px}.iprep-qbody{padding:0 16px 12px 20px}}@media (width<=768px){header{flex-wrap:wrap;gap:6px;padding:6px 10px}.badge{display:none}.view-tabs{order:1}.header-center{flex-basis:100%;order:3;max-width:none}.header-right{gap:4px}.header-right select{padding:4px 6px;font-size:11px}.interview-subtitle{font-size:12px}.problem-sidebar{border-right:none;border-bottom:1px solid var(--border);flex-shrink:0;width:100%;min-width:0;max-height:140px}.problem-sidebar .list-header{flex-shrink:0}.problem-sidebar .problem-list{flex-wrap:nowrap;gap:0;display:flex;overflow-x:auto}.problem-sidebar .problem-item{border-bottom:none;border-right:1px solid var(--border);white-space:nowrap;flex-shrink:0;padding:6px 10px;font-size:12px}.problem-sidebar .problem-item .pnum{min-width:18px}.problem-sidebar .problem-item .pdiff{padding:1px 4px;font-size:9px}.split-view{flex-direction:column}.editor-panel{border-right:none;border-top:1px solid var(--border);flex:1;width:100%;min-width:0}.problem-panel{max-height:45%;padding:14px 16px}.pv-header h2{font-size:15px}.pv-desc{font-size:13px}.example{padding:10px 12px;font-size:12px}.code-editor{padding:12px;font-size:13px}.editor-header{padding:6px 10px;font-size:12px}.editor-header .editor-actions{gap:4px}.run-btn,.solution-btn{padding:4px 10px;font-size:11px}.iprep{padding:12px}.iprep-header{padding:12px 14px}.iprep-title-row h3{font-size:14px}.iprep-qheader{padding:8px 14px 8px 16px;font-size:12px}.iprep-qbody{padding:0 14px 12px 16px}.iprep-qbody p{font-size:13px}}@media (width<=480px){.view-tab{padding:4px 8px;font-size:11px}.header-right select{max-width:80px;padding:3px 4px;font-size:10px}.problem-item{padding:6px 10px;font-size:12px}.problem-panel{max-height:40%}.code-editor{padding:10px;font-size:12px}.output{max-height:120px}.output pre{padding:8px 12px;font-size:11px}}