:root{--bg-primary: #0d1117;--bg-secondary: #161b22;--bg-tertiary: #1c2333;--bg-elevated: #21283b;--bg-hover: #292f3d;--text-primary: #e6edf3;--text-secondary: #8b949e;--text-muted: #6e7681;--text-accent: #58a6ff;--border-default: #30363d;--border-subtle: #21262d;--border-focus: #58a6ff;--accent-blue: #58a6ff;--accent-green: #3fb950;--accent-yellow: #d29922;--accent-red: #f85149;--accent-purple: #bc8cff;--accent-cyan: #39d2c0;--gradient-header: linear-gradient(135deg, #0d1117 0%, #161b22 50%, #1c2333 100%);--gradient-accent: linear-gradient(135deg, #58a6ff 0%, #bc8cff 100%);--gradient-success: linear-gradient(135deg, #3fb950 0%, #39d2c0 100%);--gradient-danger: linear-gradient(135deg, #f85149 0%, #d29922 100%);--font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;--font-mono: "JetBrains Mono", "Fira Code", monospace;--space-xs: 4px;--space-sm: 8px;--space-md: 16px;--space-lg: 24px;--space-xl: 32px;--radius-sm: 4px;--radius-md: 8px;--radius-lg: 12px;--radius-xl: 16px;--shadow-sm: 0 1px 2px rgba(0, 0, 0, .3);--shadow-md: 0 4px 12px rgba(0, 0, 0, .4);--shadow-lg: 0 8px 24px rgba(0, 0, 0, .5);--shadow-glow-blue: 0 0 20px rgba(88, 166, 255, .15);--shadow-glow-green: 0 0 20px rgba(63, 185, 80, .15);--transition-fast: .15s ease;--transition-normal: .25s ease;--transition-slow: .4s ease}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html,body,#root{height:100%;width:100%;overflow:hidden}body{font-family:var(--font-sans);background:var(--bg-primary);color:var(--text-primary);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}.exam-screen{display:flex;flex-direction:column;height:100vh;background:var(--bg-primary)}.exam-topbar{display:flex;align-items:center;justify-content:space-between;height:56px;padding:0 var(--space-lg);background:var(--gradient-header);border-bottom:1px solid 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var(--border-default);color:var(--text-secondary);font-size:18px;padding:6px 10px;border-radius:var(--radius-md);cursor:pointer;transition:var(--transition-fast)}.settings-btn:hover{background:var(--bg-hover);color:var(--text-primary);border-color:var(--border-focus)}.exam-content{display:flex;flex:1;overflow:hidden}.exam-left-panel{width:30%;min-width:280px;max-width:400px;border-right:1px solid var(--border-default);overflow-y:auto;background:var(--bg-secondary)}.exam-center-panel{flex:1;position:relative;overflow:hidden;background:var(--bg-primary)}.exam-right-panel{width:220px;min-width:200px;border-left:1px solid var(--border-default);display:flex;flex-direction:column;background:var(--bg-secondary)}.isometric-canvas-container{width:100%;height:100%;position:relative}.isometric-canvas{display:block}.zoom-controls{position:absolute;bottom:var(--space-lg);left:50%;transform:translate(-50%);display:flex;align-items:center;gap:var(--space-sm);padding:6px 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var(--border-default)}.submit-btn{width:100%;display:flex;align-items:center;justify-content:center;gap:var(--space-sm);padding:12px;background:var(--gradient-success);color:#fff;border:none;border-radius:var(--radius-md);font-size:14px;font-weight:600;cursor:pointer;transition:var(--transition-normal);font-family:var(--font-sans);text-transform:uppercase;letter-spacing:.5px}.submit-btn:hover{filter:brightness(1.1);transform:translateY(-1px);box-shadow:var(--shadow-glow-green)}.submit-btn:active{transform:translateY(0)}.submit-icon{font-size:18px}::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-track{background:var(--bg-primary)}::-webkit-scrollbar-thumb{background:var(--border-default);border-radius:4px}::-webkit-scrollbar-thumb:hover{background:var(--text-muted)}@keyframes fadeIn{0%{opacity:0;transform:translateY(4px)}to{opacity:1;transform:translateY(0)}}@keyframes pulse{0%,to{opacity:1}50%{opacity:.6}}@keyframes glow{0%,to{box-shadow:0 0 5px #58a6ff33}50%{box-shadow:0 0 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ease}.modal-icon{font-size:40px;text-align:center;margin-bottom:var(--space-md)}.modal-title{font-size:18px;font-weight:700;color:var(--text-primary);text-align:center;margin-bottom:var(--space-sm)}.modal-message{font-size:14px;color:var(--text-secondary);text-align:center;line-height:1.5;margin-bottom:var(--space-lg)}.modal-stats{display:grid;grid-template-columns:repeat(2,1fr);gap:var(--space-sm);margin-bottom:var(--space-lg)}.modal-stat{display:flex;flex-direction:column;align-items:center;padding:10px;background:var(--bg-tertiary);border-radius:var(--radius-md);border:1px solid var(--border-subtle)}.modal-stat-value{font-size:20px;font-weight:700;font-family:var(--font-mono);color:var(--accent-blue)}.modal-stat-label{font-size:11px;color:var(--text-muted);text-transform:uppercase}.modal-actions{display:flex;gap:var(--space-sm)}.modal-btn{flex:1;padding:12px;border-radius:var(--radius-md);font-size:14px;font-weight:600;cursor:pointer;transition:var(--transition-fast);font-family:var(--font-sans);text-align:center}.modal-btn-cancel{background:var(--bg-tertiary);border:1px solid var(--border-default);color:var(--text-secondary)}.modal-btn-cancel:hover{background:var(--bg-hover);color:var(--text-primary);border-color:var(--text-muted)}.modal-btn-confirm{background:var(--gradient-success);border:none;color:#fff}.modal-btn-confirm:hover{filter:brightness(1.1);box-shadow:var(--shadow-glow-green)}.toast-notification{position:fixed;top:var(--space-lg);right:var(--space-lg);padding:14px 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.2s}.exam-card-btn:hover:not(:disabled){opacity:.85}.exam-card-btn:disabled{opacity:.4;cursor:not-allowed}.no-exams{color:var(--text-secondary);font-size:1rem}.loading-spinner{display:flex;justify-content:center;align-items:center;height:100vh;font-size:1.2rem;color:var(--text-secondary)}.error-message{display:flex;flex-direction:column;align-items:center;justify-content:center;height:100vh;gap:1rem;color:var(--accent-red);font-size:1rem}.error-message button{padding:.5rem 1.5rem;background:var(--bg-tertiary);color:var(--text-primary);border:1px solid var(--border-default);border-radius:6px;cursor:pointer}.question-nav{display:flex;align-items:center;gap:4px}.q-nav-btn{background:none;border:1px solid var(--border-default);color:var(--text-secondary);width:28px;height:28px;border-radius:4px;cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:.85rem;transition:all .15s}.q-nav-btn:hover:not(:disabled){border-color:var(--accent-blue);color:var(--text-primary)}.q-nav-btn:disabled{opacity:.3;cursor:not-allowed}.q-nav-dot{background:var(--bg-tertiary);border:1px solid var(--border-default);color:var(--text-secondary);width:28px;height:28px;border-radius:4px;cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:.8rem;font-weight:500;transition:all .15s}.q-nav-dot:hover{border-color:var(--accent-blue)}.q-nav-active{background:var(--accent-blue);border-color:var(--accent-blue);color:#fff}.q-nav-answered:not(.q-nav-active){border-color:var(--accent-green);color:var(--accent-green)}.question-info{padding:.75rem;margin-bottom:.5rem;border-bottom:1px solid var(--border-subtle)}.question-info h3{font-size:.95rem;font-weight:600;margin:0 0 .25rem;color:var(--text-primary)}.question-desc{font-size:.8rem;color:var(--text-secondary);margin:0;line-height:1.4}.submitted-badge{padding:4px 12px;background:#3fb95026;color:var(--accent-green);border-radius:12px;font-size:.8rem;font-weight:500}.exam-timer{padding:4px 12px;border-radius:6px;font-family:Courier New,monospace;font-weight:700;font-size:1rem;background:var(--bg-tertiary);border:1px solid var(--border-default);color:var(--text-primary);transition:all .3s}.timer-warning{background:#d2992226;border-color:var(--accent-yellow);color:var(--accent-yellow)}.timer-critical{background:#f8514926;border-color:var(--accent-red);color:var(--accent-red);animation:timerPulse 1s ease-in-out infinite}@keyframes timerPulse{0%,to{opacity:1}50%{opacity:.6}}.autosave-indicator{font-size:.75rem;color:var(--text-muted)}.auth-page{min-height:100vh;display:flex;align-items:center;justify-content:center;background:var(--bg-primary);padding:2rem}.auth-card{width:100%;max-width:400px;background:var(--bg-secondary);border:1px solid var(--border-default);border-radius:var(--radius-xl);padding:2.5rem;box-shadow:var(--shadow-lg);animation:fadeIn .3s ease}.auth-logo{display:flex;align-items:center;justify-content:center;gap:var(--space-sm);margin-bottom:1.5rem}.auth-title{font-size:1.4rem;font-weight:700;color:var(--text-primary);text-align:center;margin-bottom:1.5rem}.auth-error{background:#f851491f;border:1px solid rgba(248,81,73,.3);color:var(--accent-red);padding:.75rem 1rem;border-radius:var(--radius-md);font-size:.875rem;margin-bottom:1rem}.form-group{margin-bottom:1rem}.form-group label{display:block;font-size:.85rem;font-weight:500;color:var(--text-secondary);margin-bottom:.35rem}.form-group input{width:100%;padding:.65rem .85rem;background:var(--bg-tertiary);border:1px solid var(--border-default);border-radius:var(--radius-md);color:var(--text-primary);font-size:.9rem;font-family:var(--font-sans);transition:border-color var(--transition-fast);outline:none}.form-group input::placeholder{color:var(--text-muted)}.form-group input:focus{border-color:var(--accent-blue);box-shadow:0 0 0 2px #58a6ff26}.auth-submit{width:100%;padding:.75rem;margin-top:.5rem;background:var(--gradient-accent);color:#fff;border:none;border-radius:var(--radius-md);font-size:.95rem;font-weight:600;cursor:pointer;font-family:var(--font-sans);transition:filter var(--transition-fast),transform var(--transition-fast)}.auth-submit:hover:not(:disabled){filter:brightness(1.1);transform:translateY(-1px)}.auth-submit:disabled{opacity:.6;cursor:not-allowed}.auth-link{text-align:center;margin-top:1.25rem;font-size:.85rem;color:var(--text-secondary)}.auth-link a{color:var(--accent-blue);text-decoration:none;font-weight:500}.auth-link a:hover{text-decoration:underline}.user-menu{display:flex;align-items:center;gap:.75rem;margin-left:auto}.user-menu .user-name{font-size:.875rem;color:var(--text-secondary);font-weight:500}.logout-btn{padding:.4rem .85rem;background:var(--bg-tertiary);border:1px solid var(--border-default);border-radius:var(--radius-md);color:var(--text-secondary);font-size:.8rem;font-weight:500;cursor:pointer;font-family:var(--font-sans);transition:var(--transition-fast)}.logout-btn:hover{background:#f851491f;border-color:var(--accent-red);color:var(--accent-red)}.grade-results{display:flex;flex-direction:column;gap:.75rem;padding:.5rem 0;overflow-y:auto;height:100%}.grade-total{background:var(--bg-tertiary);border:1px solid var(--border-default);border-radius:var(--radius-md);padding:1rem;text-align:center}.grade-total-label{font-size:.75rem;color:var(--text-tertiary);text-transform:uppercase;letter-spacing:.05em;margin-bottom:.25rem}.grade-total-score{font-size:1.5rem;font-weight:700;color:var(--accent-green);font-family:var(--font-mono)}.grade-question-result{background:var(--bg-tertiary);border:1px solid var(--border-default);border-radius:var(--radius-md);padding:.75rem}.grade-question-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:.5rem}.grade-question-title{font-size:.8rem;font-weight:600;color:var(--text-primary)}.grade-question-score{font-size:.8rem;font-weight:600;font-family:var(--font-mono);color:var(--accent-blue)}.grade-detail{display:flex;flex-direction:column;gap:.4rem;margin-bottom:.5rem}.grade-score-bar{display:flex;align-items:center;gap:.5rem}.grade-bar-label{font-size:.7rem;color:var(--text-tertiary);min-width:3rem}.grade-bar-track{flex:1;height:6px;background:var(--bg-secondary);border-radius:3px;overflow:hidden}.grade-bar-fill{height:100%;background:var(--accent-green);border-radius:3px;transition:width .5s 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