:root{--bg:#0d1117;--bg-secondary:#161b22;--text:#c9d1d9;--text-muted:#8b949e;--border:#30363d;--link:#58a6ff;--easy:#3fb950;--medium:#d29922;--hard:#f85149;--tag-bg:#21262d;}*{box-sizing:border-box;margin:0;padding:0;}body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen,Ubuntu,sans-serif;background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh;display:flex;flex-direction:column;}a{color:var(--link);text-decoration:none;}a:hover{text-decoration:underline;}body>header{background:var(--bg-secondary);border-bottom:1px solid var(--border);}body>header nav{max-width:1200px;margin:0 auto;padding:1rem 2rem;display:flex;gap:1.5rem;align-items:center;}body>header .logo{font-weight:bold;font-size:1.25rem;color:var(--text);}.nav-search{margin-left:auto;position:relative;}.nav-search input{padding:0.4rem 0.75rem;background:var(--bg);border:1px solid var(--border);border-radius:6px;color:var(--text);font-size:0.875rem;width:250px;}.nav-search 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th.sortable{cursor:pointer;user-select:none;transition:color 0.2s;}.problems-table th.sortable:hover{color:var(--link);}.problems-table th.sortable::after{content:'';display:inline-block;margin-left:0.5rem;opacity:0.3;}.problems-table th.sortable:hover::after{content:'↕';opacity:0.5;}.problems-table th.sortable.sort-asc::after{content:'↑';opacity:1;}.problems-table th.sortable.sort-desc::after{content:'↓';opacity:1;}.problems-table tr:hover{background:var(--bg-secondary);}.difficulty{display:inline-block;padding:0.25rem 0.75rem;border-radius:999px;font-size:0.75rem;font-weight:600;text-transform:capitalize;text-decoration:none;transition:all 0.2s;}.difficulty:hover{text-decoration:none;filter:brightness(1.2);}.difficulty.easy{background:rgba(63,185,80,0.2);color:var(--easy);}.difficulty.medium{background:rgba(210,153,34,0.2);color:var(--medium);}.difficulty.hard{background:rgba(248,81,73,0.2);color:var(--hard);}.tags{display:flex;flex-wrap:wrap;gap:0.5rem;}.tag{display:inline-block;padding:0.25rem 0.5rem;background:var(--tag-bg);border-radius:4px;font-size:0.75rem;color:var(--text-muted);}.problem-header{margin-bottom:2rem;}.problem-header .meta{display:flex;align-items:center;gap:1rem;margin:1rem 0;}.leetcode-link{font-size:0.875rem;color:var(--text-muted);}.description-text{background:var(--bg-secondary);padding:1.5rem;border-radius:8px;border:1px solid var(--border);color:var(--text);line-height:1.8;}.description-text p{margin-bottom:1rem;}.description-text p:last-child{margin-bottom:0;}.description-text code{background:var(--bg);padding:0.125rem 0.5rem;border-radius:4px;font-family:'SF Mono','Fira 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details{background:var(--bg-secondary);padding:1rem;border-radius:8px;border:1px solid var(--border);}.hints summary{cursor:pointer;font-weight:600;color:var(--link);}.hints dl{margin-top:1rem;}.hints dt{font-weight:600;color:var(--text-muted);margin-top:1rem;}.hints dd{margin-left:1rem;}.complexity details{background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;}.complexity summary{padding:1rem;cursor:pointer;font-weight:600;color:var(--link);user-select:none;}.complexity summary:hover{background:rgba(88,166,255,0.1);border-radius:8px;}.complexity details[open] summary{border-radius:8px 8px 0 0;}.complexity ul{list-style:disc;list-style-position:outside;margin:0;padding:1rem;padding-left:2rem;border-top:1px solid var(--border);}.complexity li{padding:0.25rem 0;margin-left:0.5rem;}.complexity code{background:var(--bg-secondary);padding:0.125rem 0.5rem;border-radius:4px;color:var(--link);}.notes details{background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;}.notes summary{padding:1rem;cursor:pointer;font-weight:600;color:var(--link);user-select:none;}.notes summary:hover{background:rgba(88,166,255,0.1);border-radius:8px;}.notes details[open] summary{border-radius:8px 8px 0 0;}.notes-content{padding:1rem;border-top:1px solid var(--border);font-size:0.9rem;line-height:1.6;}.notes-content p{margin-bottom:1rem;}.notes-content p:last-child{margin-bottom:0;}.notes-content code{background:var(--bg);padding:0.125rem 0.5rem;border-radius:4px;font-family:'SF Mono','Fira Code',monospace;}.notes-content pre{background:var(--bg);padding:1rem;border-radius:6px;overflow-x:auto;margin:1rem 0;}.notes-content pre code{background:none;padding:0;}.notes-content ul,.notes-content ol{margin:1rem 0;padding-left:1.5rem;}.notes-content li{margin-bottom:0.5rem;}.notes-content h1,.notes-content h2,.notes-content h3{margin-top:1.5rem;margin-bottom:0.75rem;}.notes-content h1:first-child,.notes-content h2:first-child,.notes-content h3:first-child{margin-top:0;}.tabs{position:relative;}.tab-buttons{display:flex;gap:0.5rem;margin-bottom:1rem;}.tab-buttons input[type="radio"]{position:absolute;opacity:0;pointer-events:none;}.tab-buttons label{padding:0.5rem 1rem;background:var(--bg-secondary);border:1px solid var(--border);border-radius:6px;color:var(--text-muted);cursor:pointer;font-size:0.875rem;font-weight:600;transition:all 0.2s;}.tab-buttons label:hover{color:var(--text);border-color:var(--text-muted);}.tab-buttons input[type="radio"]:checked+label{background:var(--link);color:var(--bg);border-color:var(--link);}.tab-panels .tab-panel{display:none;}.tab-buttons input:nth-of-type(1):checked~.tab-buttons+.tab-panels .tab-panel:nth-child(1),.tabs:has(input:nth-of-type(1):checked) .tab-panel:nth-child(1){display:block;}.tabs:has(input:nth-of-type(2):checked) .tab-panel:nth-child(2){display:block;}.tabs:has(input:nth-of-type(3):checked) .tab-panel:nth-child(3){display:block;}.tabs:has(input:nth-of-type(4):checked) .tab-panel:nth-child(4){display:block;}.tabs:has(input:nth-of-type(5):checked) .tab-panel:nth-child(5){display:block;}.tabs:has(input:nth-of-type(6):checked) .tab-panel:nth-child(6){display:block;}.tab-panel details{background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;}.tab-panel summary{padding:1rem;cursor:pointer;font-weight:600;color:var(--link);user-select:none;}.tab-panel summary:hover{background:rgba(88,166,255,0.1);border-radius:8px;}.tab-panel details[open] summary{border-radius:8px 8px 0 0;}.tab-panel pre{margin:0;border-top:1px solid var(--border);border-radius:0 0 8px 8px;overflow-x:auto;}.tab-panel code{font-family:'SF Mono','Fira Code',monospace;font-size:0.875rem;line-height:1.5;}.solution-toggles{display:flex;flex-wrap:wrap;gap:0.5rem;align-items:flex-start;}.solution-toggle{display:contents;}.solution-toggle input[type="radio"]{display:none;}.solution-btn{display:inline-block;padding:0.5rem 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var(--border);border-radius:4px;cursor:pointer;font-size:1rem;color:var(--text-muted);transition:all 0.2s;}.solution-close:hover{background:var(--link);color:var(--bg);border-color:var(--link);}.back-link{margin-top:2rem;padding-top:1rem;}.problems-table+.back-link{margin-top:1.5rem;border-top:none;}.last-updated{margin-top:1rem;font-size:0.75rem;color:var(--text-muted);}footer .git-info{margin-top:0.5rem;font-size:0.75rem;color:var(--text-muted);}footer .git-info a{color:var(--text-muted);}footer .git-info a:hover{color:var(--link);}.tags-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:1rem;margin-top:1.5rem;}.tag-card{display:flex;flex-direction:column;padding:1rem 1.25rem;background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;text-decoration:none;transition:all 0.2s;}.tag-card:hover{border-color:var(--link);background:rgba(88,166,255,0.05);text-decoration:none;}.tag-card .tag-name{font-size:1rem;font-weight:600;color:var(--text);margin-bottom:0.25rem;}.tag-card .tag-count{font-size:0.8rem;color:var(--text-muted);}.home-nav{margin-bottom:2rem;}.home-nav .nav-link{display:inline-block;padding:0.5rem 1rem;background:var(--bg-secondary);border:1px solid var(--border);border-radius:6px;color:var(--link);font-size:0.875rem;}.home-nav .nav-link:hover{border-color:var(--link);text-decoration:none;}.difficulties-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:1rem;margin-top:1.5rem;}.difficulty-card{display:flex;flex-direction:column;padding:1.5rem;background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;text-decoration:none;transition:all 0.2s;text-align:center;}.difficulty-card:hover{text-decoration:none;}.difficulty-card.easy{border-color:var(--easy);}.difficulty-card.easy:hover{background:rgba(63,185,80,0.1);}.difficulty-card.medium{border-color:var(--medium);}.difficulty-card.medium:hover{background:rgba(210,153,34,0.1);}.difficulty-card.hard{border-color:var(--hard);}.difficulty-card.hard:hover{background:rgba(248,81,73,0.1);}.difficulty-card .difficulty-name{font-size:1.25rem;font-weight:600;margin-bottom:0.5rem;}.difficulty-card.easy .difficulty-name{color:var(--easy);}.difficulty-card.medium .difficulty-name{color:var(--medium);}.difficulty-card.hard .difficulty-name{color:var(--hard);}.difficulty-card .difficulty-count{font-size:0.875rem;color:var(--text-muted);}.difficulty-header{display:flex;flex-direction:column;align-items:center;padding:2rem;background:var(--bg-secondary);border:2px solid var(--border);border-radius:12px;margin-bottom:2rem;text-align:center;}.difficulty-header .difficulty-name{font-size:2rem;font-weight:700;margin-bottom:0.5rem;}.difficulty-header .difficulty-count{font-size:1rem;color:var(--text-muted);}.difficulty-header.easy{border-color:var(--easy);}.difficulty-header.easy .difficulty-name{color:var(--easy);}.difficulty-header.medium{border-color:var(--medium);}.difficulty-header.medium .difficulty-name{color:var(--medium);}.difficulty-header.hard{border-color:var(--hard);}.difficulty-header.hard .difficulty-name{color:var(--hard);}@media (max-width:768px){body>header nav{padding:0.75rem 1rem;flex-wrap:wrap;gap:0.75rem;}body>header .logo{font-size:1rem;margin-right:auto;}body>header nav>a:not(.logo){font-size:0.8rem;}.nav-search{order:10;width:100%;margin-left:0;margin-top:0.5rem;}.nav-search input{width:100%;}main{padding:1rem;}h1{font-size:1.5rem;}h2{font-size:1.25rem;}.filter-bar{flex-direction:column;}.filter-bar input{max-width:100%;}.problems-table{display:block;}.problems-table thead{display:none;}.problems-table tbody{display:flex;flex-direction:column;gap:0.75rem;}.problems-table tr{display:flex;flex-direction:column;background:var(--bg-secondary);border:1px solid var(--border);border-radius:8px;padding:0.75rem;gap:0.5rem;}.problems-table tr:hover{background:var(--bg-secondary);}.problems-table td{padding:0;border:none;}.problems-table td:first-child{font-weight:600;}.problems-table td:first-child a{font-size:1rem;}.problems-table .tags{margin-top:0.25rem;}.problems-table .tag{font-size:0.7rem;}.tags-grid,.difficulties-grid{grid-template-columns:1fr 1fr;gap:0.75rem;}.tag-card,.difficulty-card{padding:0.75rem;}footer{padding:1rem;}.footer-content{flex-direction:column;gap:0.5rem;text-align:center;}.footer-left,.footer-right{font-size:0.75rem;}.difficulty-header{padding:1.5rem;margin-bottom:1.5rem;}.difficulty-header .difficulty-name{font-size:1.5rem;}.difficulty-header .difficulty-count{font-size:0.875rem;}}@media (max-width:480px){body>header nav>a:not(.logo){font-size:0.75rem;}.tags-grid,.difficulties-grid{grid-template-columns:1fr;}.search-shortcut{display:none;}.nav-search input{padding-right:0.75rem;}}