:root{--bg-primary: #0d1117;--bg-secondary: #161b22;--bg-tertiary: #21262d;--bg-card: #1c2128;--text-primary: #e6edf3;--text-secondary: #8b949e;--text-muted: #6e7681;--accent-primary: #58a6ff;--accent-success: #3fb950;--accent-warning: #d29922;--accent-danger: #f85149;--accent-purple: #a371f7;--border-color: #30363d;--border-radius: 8px;--border-radius-lg: 12px;--shadow: 0 4px 12px rgba(0, 0, 0, .4);--shadow-lg: 0 8px 24px rgba(0, 0, 0, .6);--transition: all .2s ease;--font-mono: "JetBrains Mono", "Fira Code", monospace;--font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html{font-size:16px;scroll-behavior:smooth}body{font-family:var(--font-sans);background-color:var(--bg-primary);color:var(--text-primary);line-height:1.6;min-height:100vh}h1,h2,h3,h4,h5,h6{font-weight:600;line-height:1.3;margin-bottom:.5em}h1{font-size:2.5rem}h2{font-size:2rem}h3{font-size:1.5rem}h4{font-size:1.25rem}p{margin-bottom:1rem}a{color:var(--accent-primary);text-decoration:none;transition:var(--transition)}a:hover{text-decoration:underline}.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;padding:.75rem 1.5rem;font-size:1rem;font-weight:500;border:none;border-radius:var(--border-radius);cursor:pointer;transition:var(--transition);text-decoration:none}.btn-primary{background:var(--accent-primary);color:var(--bg-primary)}.btn-primary:hover{background:#79b8ff;text-decoration:none}.btn-secondary{background:var(--bg-tertiary);color:var(--text-primary);border:1px solid var(--border-color)}.btn-secondary:hover{background:var(--border-color);text-decoration:none}.btn-success{background:var(--accent-success);color:var(--bg-primary)}.btn-danger{background:var(--accent-danger);color:#fff}.btn-sm{padding:.5rem 1rem;font-size:.875rem}.btn-lg{padding:1rem 2rem;font-size:1.125rem}.btn:disabled{opacity:.5;cursor:not-allowed}.form-group{margin-bottom:1.5rem}.form-label{display:block;margin-bottom:.5rem;font-weight:500;color:var(--text-secondary)}.form-input,.form-select,.form-textarea{width:100%;padding:.75rem 1rem;font-size:1rem;font-family:inherit;background:var(--bg-tertiary);border:1px solid var(--border-color);border-radius:var(--border-radius);color:var(--text-primary);transition:var(--transition)}.form-input:focus,.form-select:focus,.form-textarea:focus{outline:none;border-color:var(--accent-primary);box-shadow:0 0 0 3px #58a6ff33}.form-input::placeholder{color:var(--text-muted)}.form-textarea{min-height:120px;resize:vertical}.card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--border-radius-lg);padding:1.5rem}.card-header{margin-bottom:1rem;padding-bottom:1rem;border-bottom:1px solid var(--border-color)}.card-title{font-size:1.25rem;margin-bottom:0}.badge{display:inline-flex;align-items:center;padding:.25rem .75rem;font-size:.75rem;font-weight:600;border-radius:9999px;text-transform:uppercase}.badge-c{background:#f8514933;color:var(--accent-danger)}.badge-b{background:#d2992233;color:var(--accent-warning)}.badge-a{background:#3fb95033;color:var(--accent-success)}.badge-s{background:#a371f733;color:var(--accent-purple)}.container{max-width:1200px;margin:0 auto;padding:0 1.5rem}.container-sm{max-width:600px}.container-md{max-width:800px}.grid{display:grid;gap:1.5rem}.grid-2{grid-template-columns:repeat(2,1fr)}.grid-3{grid-template-columns:repeat(3,1fr)}.grid-4{grid-template-columns:repeat(4,1fr)}@media(max-width:768px){.grid-2,.grid-3,.grid-4{grid-template-columns:1fr}}.flex{display:flex}.flex-col{flex-direction:column}.items-center{align-items:center}.justify-center{justify-content:center}.justify-between{justify-content:space-between}.gap-1{gap:.5rem}.gap-2{gap:1rem}.gap-3{gap:1.5rem}.mt-1{margin-top:.5rem}.mt-2{margin-top:1rem}.mt-3{margin-top:1.5rem}.mt-4{margin-top:2rem}.mb-1{margin-bottom:.5rem}.mb-2{margin-bottom:1rem}.mb-3{margin-bottom:1.5rem}.mb-4{margin-bottom:2rem}.text-center{text-align:center}.text-muted{color:var(--text-secondary)}.text-success{color:var(--accent-success)}.text-danger{color:var(--accent-danger)}.text-warning{color:var(--accent-warning)}.timer{display:inline-flex;align-items:center;gap:.5rem;padding:.5rem 1rem;background:var(--bg-tertiary);border-radius:var(--border-radius);font-family:var(--font-mono);font-size:1.25rem;font-weight:600}.timer.warning{background:#d2992233;color:var(--accent-warning)}.timer.danger{background:#f8514933;color:var(--accent-danger)}.qcm-options{display:flex;flex-direction:column;gap:.75rem}.qcm-option{display:flex;align-items:center;gap:1rem;padding:1rem 1.25rem;background:var(--bg-tertiary);border:2px solid var(--border-color);border-radius:var(--border-radius);cursor:pointer;transition:var(--transition)}.qcm-option:hover{border-color:var(--accent-primary)}.qcm-option.selected{border-color:var(--accent-primary);background:#58a6ff1a}.qcm-option input{display:none}.qcm-option-marker{width:2rem;height:2rem;display:flex;align-items:center;justify-content:center;background:var(--bg-secondary);border-radius:50%;font-weight:600}.qcm-option.selected .qcm-option-marker{background:var(--accent-primary);color:var(--bg-primary)}.progress-bar{width:100%;height:8px;background:var(--bg-tertiary);border-radius:4px;overflow:hidden}.progress-bar-fill{height:100%;background:var(--accent-primary);border-radius:4px;transition:width .3s ease}.code-editor-container{border:1px solid var(--border-color);border-radius:var(--border-radius);overflow:hidden}.code-output{background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--border-radius);padding:1rem;font-family:var(--font-mono);font-size:.875rem;white-space:pre-wrap;max-height:200px;overflow-y:auto}.code-output.error{border-color:var(--accent-danger);color:var(--accent-danger)}.code-output.success{border-color:var(--accent-success)}table{width:100%;border-collapse:collapse}th,td{padding:1rem;text-align:left;border-bottom:1px solid var(--border-color)}th{font-weight:600;color:var(--text-secondary);background:var(--bg-tertiary)}tr:hover td{background:var(--bg-secondary)}.alert{padding:1rem 1.25rem;border-radius:var(--border-radius);margin-bottom:1rem}.alert-warning{background:#d2992233;border:1px solid var(--accent-warning);color:var(--accent-warning)}.alert-danger{background:#f8514933;border:1px solid var(--accent-danger);color:var(--accent-danger)}.alert-success{background:#3fb95033;border:1px solid var(--accent-success);color:var(--accent-success)}.modal-overlay{position:fixed;inset:0;background:#000c;display:flex;align-items:center;justify-content:center;z-index:1000;backdrop-filter:blur(4px)}.modal-overlay.active,.modal-overlay:not(.hidden){opacity:1;visibility:visible}.modal{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--border-radius-lg);padding:2rem;max-width:500px;width:90%;transform:scale(.9);transition:var(--transition)}.modal-overlay.active .modal{transform:scale(1)}.cheat-warning{position:fixed;top:50%;left:50%;transform:translate(-50%,-50%);background:var(--bg-card);border:2px solid var(--accent-danger);border-radius:var(--border-radius-lg);padding:2rem;text-align:center;z-index:9999;animation:shake .5s ease-in-out}@keyframes shake{0%,to{transform:translate(-50%,-50%) rotate(0)}25%{transform:translate(-50%,-50%) rotate(-2deg)}75%{transform:translate(-50%,-50%) rotate(2deg)}}.navbar{background:var(--bg-secondary);border-bottom:1px solid var(--border-color);padding:1rem 0;position:sticky;top:0;z-index:100}.navbar-content{display:flex;align-items:center;justify-content:space-between}.navbar-brand{font-size:1.25rem;font-weight:700;color:var(--text-primary);text-decoration:none}.navbar-nav{display:flex;align-items:center;gap:1.5rem;list-style:none}.navbar-nav a{color:var(--text-secondary);text-decoration:none;transition:var(--transition)}.navbar-nav a:hover,.navbar-nav a.active{color:var(--text-primary)}.stat-card{text-align:center;padding:1.5rem}.stat-value{font-size:2.5rem;font-weight:700;color:var(--accent-primary)}.stat-label{color:var(--text-secondary);font-size:.875rem;margin-top:.25rem}.question-nav{display:flex;flex-wrap:wrap;gap:.5rem}.question-nav-item{width:2.5rem;height:2.5rem;display:flex;align-items:center;justify-content:center;background:var(--bg-tertiary);border:1px solid var(--border-color);border-radius:var(--border-radius);font-weight:500;cursor:pointer;transition:var(--transition)}.question-nav-item:hover{border-color:var(--accent-primary)}.question-nav-item.current{background:var(--accent-primary);color:var(--bg-primary);border-color:var(--accent-primary)}.question-nav-item.answered{background:var(--accent-success);color:var(--bg-primary);border-color:var(--accent-success)}.hide-scrollbar{-ms-overflow-style:none;scrollbar-width:none}.hide-scrollbar::-webkit-scrollbar{display:none}.loader{width:40px;height:40px;border:3px solid var(--bg-tertiary);border-top-color:var(--accent-primary);border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.hidden{display:none!important}