:root{--bg:#0f0f1a;--bg-card:#1a1a2e;--bg-input:#16213e;--text:#e0e0e0;--text-muted:#888;--primary:#6c63ff;--primary-hover:#5a52d5;--success:#4caf50;--warning:#ff9800;--danger:#f44336;--border:#2a2a4a}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--bg);color:var(--text);min-height:100vh;font-family:Segoe UI,system-ui,-apple-system,sans-serif}a{color:var(--primary);text-decoration:none}a:hover{color:var(--primary-hover)}.main-nav{background:var(--bg-card);border-bottom:1px solid var(--border);z-index:100;justify-content:space-between;align-items:center;padding:.75rem 2rem;display:flex;position:sticky;top:0}.nav-logo{color:var(--primary);font-size:1.5rem;font-weight:700}.nav-links{align-items:center;gap:1.5rem;display:flex}.nav-links a{color:var(--text);font-weight:500}.nav-links a:hover{color:var(--primary)}.nav-logout,.lang-switch{border:1px solid var(--border);color:var(--text);cursor:pointer;background:0 0;border-radius:6px;padding:.4rem .8rem;font-size:.85rem}.nav-logout:hover,.lang-switch:hover{border-color:var(--primary);color:var(--primary)}.main-content{max-width:1200px;margin:0 auto;padding:2rem}.auth-page{justify-content:center;align-items:center;min-height:100vh;display:flex}.auth-card{background:var(--bg-card);text-align:center;border-radius:12px;width:100%;max-width:400px;padding:2.5rem}.auth-card h1{color:var(--primary);margin-bottom:.25rem}.auth-card>p{color:var(--text-muted);margin-bottom:2rem}.auth-card h2{margin-bottom:1.5rem}.auth-card form{flex-direction:column;gap:.75rem;display:flex}input,.auth-card button[type=submit],.submit-btn,.ai-btn{border:1px solid var(--border);border-radius:8px;padding:.75rem 1rem;font-size:1rem}input{background:var(--bg-input);color:var(--text)}input:focus{border-color:var(--primary);outline:none}button[type=submit],.submit-btn{background:var(--primary);color:#fff;cursor:pointer;border:none;font-weight:600}button[type=submit]:hover,.submit-btn:hover{background:var(--primary-hover)}button:disabled{opacity:.6;cursor:not-allowed}.error{color:var(--danger);background:#f443361a;border-radius:6px;margin-bottom:1rem;padding:.5rem}.dashboard h1{margin-bottom:.5rem}.welcome p{color:var(--text-muted);margin-bottom:2rem}.dashboard-grid{grid-template-columns:1fr 300px;gap:2rem;display:grid}.courses-list{flex-direction:column;gap:1rem;display:flex}.course-card{background:var(--bg-card);border:1px solid var(--border);color:var(--text);border-radius:10px;padding:1.5rem;transition:border-color .2s;display:block}.course-card:hover{border-color:var(--primary)}.course-card h2{color:var(--text);margin-bottom:.5rem}.course-card p{color:var(--text-muted)}.topics-list{flex-direction:column;gap:.75rem;display:flex}.topic-card{background:var(--bg-card);border:1px solid var(--border);color:var(--text);border-radius:8px;padding:1.25rem;display:block}.topic-card:hover{border-color:var(--primary)}.topic-card h3{margin-bottom:.5rem}.topic-progress{background:var(--border);border-radius:3px;height:6px;margin-bottom:.5rem}.topic-progress-bar{background:var(--success);border-radius:3px;height:100%;transition:width .3s}.tabs{gap:.5rem;margin-bottom:1.5rem;display:flex}.tabs button{border:1px solid var(--border);color:var(--text-muted);cursor:pointer;background:0 0;border-radius:6px;padding:.5rem 1.25rem}.tabs button.active{background:var(--primary);color:#fff;border-color:var(--primary)}.theory-content{background:var(--bg-card);border-radius:10px;padding:2rem;line-height:1.7}.theory-content h1,.theory-content h2,.theory-content h3{margin:1.5rem 0 .75rem}.theory-content code{background:var(--bg-input);border-radius:4px;padding:.15rem .4rem;font-size:.9em}.theory-content pre{background:var(--bg-input);border-radius:8px;margin:1rem 0;padding:1rem;overflow-x:auto}.tasks-list{flex-direction:column;gap:.5rem;display:flex}.task-card{background:var(--bg-card);border:1px solid var(--border);color:var(--text);border-radius:8px;align-items:center;gap:1rem;padding:1rem 1.25rem;display:flex}.task-card:hover{border-color:var(--primary)}.task-card.solved{border-left:3px solid var(--success)}.task-status{width:24px;font-size:1.2rem}.task-title{flex:1}.task-points{color:var(--text-muted)}.difficulty{font-size:.85rem;font-weight:600}.difficulty.easy{color:var(--success)}.difficulty.medium{color:var(--warning)}.difficulty.hard{color:var(--danger)}.task-info{grid-template-columns:1fr 1fr;gap:2rem;margin-bottom:1.5rem;display:grid}.task-info-left,.task-info-right{min-width:0}.task-editor-section{width:100%}.task-meta{color:var(--text-muted);gap:1rem;margin:.75rem 0 1.5rem;display:flex}.task-description{margin-bottom:1.5rem;line-height:1.7}.task-actions{gap:.75rem;margin-top:.75rem;display:flex}.ai-btn{border:1px solid var(--primary);color:var(--primary);cursor:pointer;background:0 0}.ai-btn:hover{background:#6c63ff1a}.task-result{margin-top:1.5rem}.result-status{align-items:center;gap:1rem;margin-bottom:1rem;display:flex}.result-status h3{font-size:1.25rem}.points-badge{background:var(--success);color:#fff;border-radius:20px;padding:.25rem .75rem;font-weight:600}.compile-error{background:var(--bg-input);border-left:3px solid #ff9800;border-radius:6px;margin-top:.75rem;padding:1rem;overflow-x:auto}.compile-error pre{white-space:pre-wrap;word-break:break-word;color:#ff9800;margin:0;font-size:.85rem}.test-results{flex-direction:column;gap:.5rem;display:flex}.test-case{background:var(--bg-input);border-radius:6px;gap:.75rem;padding:.75rem;display:flex}.test-case.passed{border-left:3px solid var(--success)}.test-case.failed{border-left:3px solid var(--danger)}.test-icon{font-size:1.2rem}.test-case code{font-size:.85rem}.ai-review{background:var(--bg-input);border-left:3px solid var(--primary);border-radius:8px;margin-top:1rem;padding:1rem}.ai-pending{opacity:.6;font-style:italic}.bonus-label{opacity:.85;font-size:.85em}.resubmit-hint{opacity:.7;margin-top:.75rem;font-size:.85rem;font-style:italic}.ai-chat{background:var(--bg-card);border:1px solid var(--border);border-radius:10px;margin-top:1rem;overflow:hidden}.ai-chat h3{border-bottom:1px solid var(--border);padding:.75rem 1rem}.ai-chat-messages{max-height:300px;padding:1rem;overflow-y:auto}.ai-msg{gap:.5rem;margin-bottom:.75rem;display:flex}.ai-msg p{background:var(--bg-input);border-radius:8px;padding:.5rem .75rem}.ai-msg-user{justify-content:flex-end}.ai-msg-markdown{background:var(--bg-input);border-radius:8px;max-width:100%;padding:.5rem .75rem;font-size:.9rem;line-height:1.6;overflow-x:auto}.ai-msg-markdown p{margin:0 0 .5rem}.ai-msg-markdown p:last-child{margin-bottom:0}.ai-msg-markdown code{background:#ffffff14;border-radius:4px;padding:.15rem .35rem;font-family:Cascadia Code,Fira Code,Consolas,monospace;font-size:.85em}.ai-msg-markdown pre{border:1px solid var(--border);background:#ffffff0f;border-radius:6px;margin:.5rem 0;padding:.75rem;overflow-x:auto}.ai-msg-markdown pre code{background:0 0;padding:0;font-size:.85em}.ai-msg-markdown ul,.ai-msg-markdown ol{margin:.5rem 0;padding-left:1.5rem}.ai-msg-markdown li{margin-bottom:.2rem}.ai-msg-markdown h1,.ai-msg-markdown h2,.ai-msg-markdown h3{margin:.75rem 0 .4rem;font-size:1em;font-weight:600}.ai-msg-markdown strong{color:var(--text)}.ai-msg-markdown blockquote{border-left:3px solid var(--primary);color:var(--text-muted);margin:.5rem 0;padding:.25rem .75rem}.ai-chat-input{border-top:1px solid var(--border);display:flex}.ai-chat-input input{background:0 0;border:none;flex:1;padding:.75rem}.ai-chat-input button{background:var(--primary);color:#fff;cursor:pointer;border:none;padding:.75rem 1rem}.leaderboard-table{border-collapse:collapse;width:100%;margin-top:1rem}.leaderboard-table th{text-align:left;border-bottom:2px solid var(--border);color:var(--text-muted);padding:.75rem}.leaderboard-table td{border-bottom:1px solid var(--border);padding:.75rem}.leaderboard-table .rank{width:50px;font-size:1.25rem}.leaderboard-table .points{color:var(--primary);font-weight:700}.top-1{background:#ffd7000d}.top-2{background:#c0c0c00d}.top-3{background:#cd7f320d}.leaderboard-widget{background:var(--bg-card);border:1px solid var(--border);border-radius:10px;padding:1.25rem}.leaderboard-widget h3{margin-bottom:.75rem}.leaderboard-widget ol{padding-left:0;list-style:none}.leaderboard-widget li{border-bottom:1px solid var(--border);justify-content:space-between;padding:.5rem 0;display:flex}.lb-points{color:var(--primary);font-weight:600}.profile-card{background:var(--bg-card);border-radius:12px;align-items:center;gap:2rem;margin-top:1.5rem;padding:2rem;display:flex}.profile-avatar{background:var(--primary);color:#fff;border-radius:50%;justify-content:center;align-items:center;width:80px;height:80px;font-size:2rem;font-weight:700;display:flex}.profile-info{flex:1}.profile-info h2{margin-bottom:.25rem}.profile-info p{color:var(--text-muted)}.profile-stats{gap:2rem;display:flex}.stat{text-align:center}.stat-value{font-size:1.5rem;font-weight:700;display:block}.stat-label{color:var(--text-muted);font-size:.85rem}.profile-section{background:var(--bg-card);border-radius:12px;margin-top:2rem;padding:1.5rem 2rem}.profile-section h2{margin-bottom:1.25rem;font-size:1.1rem}.profile-section h3.progress-subtitle{color:var(--text-muted);margin:1.25rem 0 .75rem;font-size:.95rem}.progress-grid{grid-template-columns:repeat(3,1fr);gap:1rem;display:grid}.progress-stat-card{background:var(--bg-input);text-align:center;border-radius:10px;padding:1rem}.progress-stat-value{color:var(--primary);font-size:1.75rem;font-weight:700;display:block}.progress-stat-label{color:var(--text-muted);margin-top:.25rem;font-size:.8rem;display:block}.difficulty-progress{flex-direction:column;gap:.6rem;display:flex}.diff-row{align-items:center;gap:.75rem;display:flex}.diff-label{flex-shrink:0;width:70px;font-size:.85rem;font-weight:600}.diff-easy{color:#4caf50}.diff-medium{color:#ff9800}.diff-hard{color:#f44336}.diff-bar-track{background:var(--bg-input);border-radius:4px;flex:1;height:8px;overflow:hidden}.diff-bar{border-radius:4px;height:100%;transition:width .4s}.diff-bar-easy{background:#4caf50}.diff-bar-medium{background:#ff9800}.diff-bar-hard{background:#f44336}.diff-count{text-align:right;width:28px;color:var(--text-muted);flex-shrink:0;font-size:.85rem}.diff-badge{text-transform:uppercase;letter-spacing:.04em;border-radius:4px;padding:.15rem .5rem;font-size:.7rem;font-weight:600;display:inline-block}.diff-badge-easy{color:#4caf50;background:#4caf5026}.diff-badge-medium{color:#ff9800;background:#ff980026}.diff-badge-hard{color:#f44336;background:#f4433626}.no-data{color:var(--text-muted);font-size:.95rem}.submission-history{flex-direction:column;gap:.75rem;display:flex}.submission-item{background:var(--bg-input);border:1px solid var(--border);border-radius:8px;overflow:hidden}.submission-header{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:1rem;padding:.75rem 1rem;display:flex}.submission-meta{flex-wrap:wrap;flex:1;align-items:center;gap:.6rem;display:flex}.submission-task-title{font-size:.95rem;font-weight:500}.submission-lang{color:var(--text-muted);background:var(--bg-card);border-radius:4px;padding:.1rem .45rem;font-size:.8rem}.submission-right{flex-wrap:wrap;align-items:center;gap:.75rem;display:flex}.submission-status{border-radius:4px;padding:.2rem .55rem;font-size:.8rem;font-weight:600}.status-accepted{color:#4caf50;background:#4caf5026}.status-wrong,.status-error{color:#f44336;background:#f4433626}.status-tle{color:#ff9800;background:#ff980026}.status-pending{color:var(--text-muted);background:#88888826}.submission-points{color:var(--primary);font-size:.8rem;font-weight:600}.submission-ai-bonus{opacity:.8;font-weight:500}.submission-time{color:var(--text-muted);font-size:.8rem}.submission-date{color:var(--text-muted);white-space:nowrap;font-size:.8rem}.toggle-code-btn{border:1px solid var(--border);color:var(--text);cursor:pointer;white-space:nowrap;background:0 0;border-radius:5px;padding:.25rem .65rem;font-size:.78rem}.toggle-code-btn:hover{border-color:var(--primary);color:var(--primary)}.submission-code{border-top:1px solid var(--border);background:var(--bg);color:var(--text);white-space:pre;margin:0;padding:1rem;font-family:Cascadia Code,Fira Code,Consolas,monospace;font-size:.82rem;line-height:1.5;overflow-x:auto}.submission-ai-review{border-top:1px solid var(--border);background:#6366f10f;padding:.75rem 1rem}.ai-review-label{color:var(--primary);margin-bottom:.35rem;font-size:.78rem;font-weight:600;display:block}.submission-ai-review p{color:var(--text);margin:0;font-size:.87rem;line-height:1.5}@media (width<=768px){.dashboard-grid,.task-info{grid-template-columns:1fr}.main-nav{flex-direction:column;gap:.5rem}.profile-card{text-align:center;flex-direction:column}.progress-grid{grid-template-columns:1fr 1fr}.submission-header{flex-direction:column;align-items:flex-start}}
