:root{--bg-primary: #050505;--bg-secondary: #0f1012;--bg-card: rgba(255, 255, 255, .03);--bg-glass: rgba(20, 20, 22, .6);--bg-glass-strong: rgba(10, 10, 12, .85);--gpa-green-light: #34d399;--gpa-green: #10b981;--gpa-green-dark: #059669;--text-primary: #f0f4f8;--text-secondary: #94a3b8;--text-tertiary: #64748b;--text-muted: #475569;--accent-primary: #3b82f6;--accent-primary-hover: #2563eb;--accent-purple: #8b5cf6;--accent-purple-hover: #7c3aed;--accent-success: #10b981;--accent-error: #ef4444;--accent-warning: #f59e0b;--border-color: rgba(255, 255, 255, .1);--border-glass: rgba(255, 255, 255, .08);--shadow-glass: 0 8px 32px 0 rgba(0, 0, 0, .36);--shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, .05);--shadow-md: 0 4px 6px -1px rgba(0, 0, 0, .1), 0 2px 4px -1px rgba(0, 0, 0, .06);--glow-primary: 0 0 20px rgba(59, 130, 246, .5);--glow-purple: 0 0 20px rgba(139, 92, 246, .4);--font-xs: .75rem;--font-sm: .875rem;--font-base: 1rem;--font-lg: 1.125rem;--font-xl: 1.25rem;--font-2xl: 1.5rem;--font-3xl: 2rem;--font-4xl: 3rem;font-family:Inter,system-ui,-apple-system,sans-serif;line-height:1.6;color-scheme:dark}*{box-sizing:border-box}::-webkit-scrollbar{display:none}input::-webkit-outer-spin-button,input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}input[type=number]{-moz-appearance:textfield}body{margin:0;background-color:var(--bg-primary);color:var(--text-primary);min-height:100vh;-webkit-font-smoothing:antialiased}.app-container{display:flex;flex-direction:column;min-height:100vh;width:100%;max-width:1400px;margin:0 auto}.top-bar{background:var(--bg-secondary);padding:.5rem 1rem;font-size:var(--font-xs);color:var(--text-tertiary);text-align:center;border-bottom:1px solid var(--border-color)}.top-bar a{color:var(--accent-primary);text-decoration:none;font-weight:500;transition:opacity .2s}.top-bar a:hover{opacity:.8}.app-header{padding:1rem 1.5rem;display:flex;flex-direction:column;gap:1.5rem;border-bottom:1px solid var(--border-color);background:#050505cc;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);position:relative;z-index:100}@media(min-width:768px){.app-header{flex-direction:row;align-items:center;justify-content:space-between;position:sticky;top:0}}.header-brand{display:flex;align-items:center;gap:1rem;justify-content:space-between}.brand-icon{color:var(--accent-primary);filter:drop-shadow(0 0 5px rgba(59,130,246,.5))}.header-brand h1{margin:0;font-size:var(--font-xl);font-weight:700;letter-spacing:-.025em;background:linear-gradient(135deg,#fff,#94a3b8);background-clip:text;-webkit-background-clip:text;-webkit-text-fill-color:transparent}.theme-toggle-btn{background:transparent;border:1px solid var(--border-color);color:var(--text-secondary);padding:.5rem;border-radius:50%;display:flex;align-items:center;justify-content:center;cursor:pointer;transition:all .2s}.theme-toggle-btn:hover{color:var(--accent-warning);border-color:var(--accent-warning);transform:rotate(15deg)}.start-quiz-btn{background:linear-gradient(135deg,var(--accent-primary),var(--accent-primary-hover));color:#fff;border:none;padding:.6rem 1.2rem;border-radius:999px;font-weight:600;font-size:var(--font-sm);cursor:pointer;box-shadow:0 4px 6px -1px #3b82f64d;transition:transform .2s,box-shadow .2s;white-space:nowrap}.start-quiz-btn:hover{transform:translateY(-1px);box-shadow:0 6px 8px -1px #3b82f666}.header-user-section{display:flex;flex-direction:column;align-items:flex-end;gap:.5rem;width:100%}@media(min-width:768px){.header-user-section{width:auto;align-items:center}}.user-controls{display:flex;align-items:center;gap:1rem;justify-content:space-between;width:100%}@media(min-width:768px){.user-controls{width:auto}}.logout-btn{display:flex;align-items:center;gap:.5rem;background:var(--bg-card);border:1px solid var(--border-color);color:var(--text-secondary);padding:.5rem 1rem;border-radius:8px;cursor:pointer;transition:all .2s}.logout-btn:hover{background:var(--bg-secondary);color:var(--text-primary);border-color:var(--text-tertiary)}.auth-form-container{display:flex;flex-direction:column;gap:.5rem;width:100%;max-width:400px}.auth-form{display:flex;gap:.5rem}.auth-input{flex:1;background:var(--bg-secondary);border:1px solid var(--border-color);color:var(--text-primary);padding:.5rem .75rem;border-radius:6px;font-size:var(--font-sm);min-width:0}.auth-input:focus{outline:none;border-color:var(--accent-primary);box-shadow:0 0 0 2px #3b82f633}.auth-submit-btn{background:var(--bg-card);border:1px solid var(--border-color);color:var(--accent-primary);padding:.5rem 1rem;border-radius:6px;cursor:pointer;display:flex;align-items:center;justify-content:center}.auth-submit-btn:hover{background:var(--accent-primary);color:#fff;border-color:var(--accent-primary)}.auth-toggle-container{font-size:var(--font-xs);color:var(--text-tertiary);text-align:right}.auth-toggle-btn{background:none;border:none;color:var(--accent-primary);cursor:pointer;font-size:inherit;padding:0;text-decoration:underline}.auth-error{color:var(--accent-error);font-size:var(--font-xs);text-align:right}.main-content{flex:1;padding:2rem 1rem;display:flex;flex-direction:column;align-items:center;gap:2rem}.score-board{display:flex;gap:1rem;width:100%;max-width:600px}.card-glass{background:var(--bg-glass);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border:1px solid var(--border-glass);border-radius:16px;box-shadow:var(--shadow-glass);width:100%}.score-card{padding:1.5rem;display:flex;flex-direction:column;align-items:center;text-align:center;flex:1}.score-label{font-size:var(--font-xs);text-transform:uppercase;letter-spacing:.05em;color:var(--text-tertiary);margin-bottom:.5rem}.score-value{font-size:var(--font-2xl);font-weight:800;line-height:1}.score-value.highlight{color:var(--accent-success);text-shadow:0 0 20px rgba(16,185,129,.3)}.questions-container{width:100%;max-width:800px;display:flex;flex-direction:column;gap:1.5rem}.empty-state,.loading-state{text-align:center;padding:3rem;color:var(--text-secondary);border:1px dashed var(--border-color);border-radius:12px}.pagination-controls{display:flex;gap:.5rem;flex-wrap:wrap;justify-content:center;margin-top:auto}.pagination-btn{background:var(--bg-card);border:1px solid var(--border-color);color:var(--text-secondary);width:40px;height:40px;border-radius:8px;display:flex;align-items:center;justify-content:center;cursor:pointer;font-size:var(--font-sm);transition:all .2s}.pagination-btn:hover:not(:disabled){background:var(--bg-secondary);color:var(--text-primary);transform:translateY(-2px)}.pagination-btn.active{background:var(--accent-primary);color:#fff;border-color:var(--accent-primary);box-shadow:var(--glow-primary)}.pagination-btn:disabled{opacity:.5;cursor:not-allowed}.quiz-complete-card{padding:3rem;text-align:center;max-width:500px;margin:0 auto}.restart-btn{margin-top:1.5rem;background:var(--accent-primary);color:#fff;border:none;padding:.8rem 2rem;border-radius:8px;font-weight:600;cursor:pointer;transition:opacity .2s}.restart-btn:hover{opacity:.9}.app-footer{text-align:center;padding:3rem 1rem;border-top:1px solid var(--border-color);background:var(--bg-secondary);color:var(--text-tertiary);margin-top:auto}.footer-brand{color:var(--text-primary);font-weight:700;font-size:var(--font-lg);margin-bottom:.5rem}.footer-credits a{color:var(--text-secondary);text-decoration:none;border-bottom:1px dotted var(--text-tertiary)}.footer-credits a:hover{color:var(--accent-primary);border-color:var(--accent-primary)}.qc-header{position:relative;display:flex;justify-content:space-between;align-items:flex-start;margin-bottom:1.5rem}.qc-title{margin:0;font-size:var(--font-lg);line-height:1.4;padding-right:2.5rem}.qc-delete-btn{position:absolute;top:-5px;right:-5px;background:transparent;border:none;color:var(--text-tertiary);padding:.5rem;border-radius:50%;cursor:pointer;transition:all .2s;display:flex;align-items:center;justify-content:center}.qc-delete-btn:hover{background:#ef44441a;color:var(--accent-error)}.qc-code-block{background:#0000004d;padding:1rem;border-radius:8px;border:1px solid var(--border-color);font-family:Fira Code,Consolas,monospace;font-size:var(--font-sm);overflow-x:auto;margin-bottom:1.5rem;color:#e2e8f0}.qc-options-list{display:flex;flex-direction:column;gap:.75rem}.qc-option{position:relative;padding:1rem;border-radius:12px;border:2px solid var(--border-color);background:var(--bg-secondary);cursor:pointer;transition:all .2s cubic-bezier(.4,0,.2,1);display:flex;flex-direction:column;overflow:hidden}.qc-option:hover:not(.disabled){border-color:var(--text-tertiary);background:var(--bg-card);transform:translate(4px)}.qc-option.disabled{cursor:default;opacity:.9}.qc-option.selected{border-color:var(--accent-primary);background:#3b82f61a}.qc-option.correct{border-color:var(--accent-success);background:#10b9811a}.qc-option.wrong{border-color:var(--accent-error);background:#ef44441a}.qc-option.missed{border-color:var(--accent-success);background:transparent;border-style:dashed;opacity:.7}.qc-option-content{display:flex;align-items:center;justify-content:space-between;width:100%;z-index:1}.qc-checkbox{width:24px;height:24px;border-radius:6px;border:2px solid var(--text-tertiary);margin-right:1rem;display:flex;align-items:center;justify-content:center;flex-shrink:0;transition:all .2s;background:transparent}.qc-radio .qc-checkbox{border-radius:50%}.qc-option.selected .qc-checkbox{border-color:var(--accent-primary);background:var(--accent-primary)}.qc-option.correct .qc-checkbox{border-color:var(--accent-success);background:var(--accent-success)}.qc-option.wrong .qc-checkbox{border-color:var(--accent-error);background:var(--accent-error)}.qc-option.missed .qc-checkbox{border-color:var(--accent-success)}.qc-checkbox-inner{width:10px;height:10px;background:#fff;border-radius:2px;opacity:0;transform:scale(0);transition:all .2s}.qc-radio .qc-checkbox-inner{border-radius:50%}.qc-option.selected .qc-checkbox-inner,.qc-option.correct .qc-checkbox-inner,.qc-option.wrong .qc-checkbox-inner{opacity:1;transform:scale(1)}.qc-label{font-size:var(--font-base);color:var(--text-primary);flex:1}.qc-explanation{margin-top:.75rem;padding:.75rem;background:#0003;border-radius:6px;font-size:var(--font-sm);color:var(--text-secondary);border-left:3px solid var(--text-tertiary);animation:fadeIn .3s ease}.qc-feedback-container{margin-top:1.5rem;padding:1rem 1.5rem;border-radius:12px;border:1px solid transparent;animation:fadeIn .3s ease}.qc-feedback-container.correct{background:#10b9811a;border-color:#10b9814d;color:var(--accent-success)}.qc-feedback-container.wrong{background:#ef44441a;border-color:#ef44444d;color:var(--accent-error)}.qc-feedback-title{margin:0;font-weight:700;font-size:var(--font-base)}.qc-submit-btn{margin-top:2rem;width:100%;padding:1rem;background:var(--accent-primary);color:#fff;border:none;border-radius:12px;font-weight:600;font-size:var(--font-base);cursor:pointer;transition:opacity .2s}.qc-submit-btn:disabled{opacity:.5;cursor:not-allowed}.qc-submit-btn:hover:not(:disabled){opacity:.9}.quiz-container{width:100%;max-width:900px;margin:0 auto;min-height:100vh;display:flex;flex-direction:column}.quiz-header-bar{position:sticky;top:0;z-index:100;background:#121212f2;backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);padding:1rem 1.5rem;border-bottom:1px solid var(--border-color);display:flex;justify-content:space-between;align-items:center;box-shadow:0 4px 6px -1px #0000001a}.quiz-quit-btn{background:transparent;border:none;color:var(--text-secondary);cursor:pointer;font-size:var(--font-sm);display:flex;align-items:center;gap:.5rem;transition:color .2s}.quiz-quit-btn:hover{color:var(--accent-error)}.quiz-timer{font-family:monospace;font-weight:700;font-size:var(--font-lg);display:flex;align-items:center;gap:.5rem;color:var(--text-primary)}.quiz-timer.low{color:var(--accent-error);animation:pulse 1s infinite}.quiz-setup-card{max-width:600px;margin:3rem auto;padding:2.5rem}.setup-title{font-size:var(--font-2xl);font-weight:800;margin-bottom:.5rem;background:linear-gradient(135deg,#fff,#94a3b8);background-clip:text;-webkit-background-clip:text;-webkit-text-fill-color:transparent}.setup-subtitle{color:var(--text-secondary);margin-bottom:2rem}.chapter-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(110px,1fr));gap:1rem;margin-bottom:1rem}.chapter-label{display:flex;align-items:center;gap:.75rem;padding:.75rem;border-radius:12px;background:var(--bg-secondary);border:1px solid var(--border-color);cursor:pointer;transition:all .2s;font-size:var(--font-sm);-webkit-user-select:none;user-select:none}.chapter-label:hover{background:var(--bg-card)}.chapter-label.active{background:#3b82f61a;border-color:var(--accent-primary);color:var(--accent-primary)}.chapter-input{accent-color:var(--accent-primary);width:16px;height:16px}.selection-actions{display:flex;gap:1rem;font-size:var(--font-xs);margin-bottom:2rem}.selection-link{background:none;border:none;color:var(--accent-primary);cursor:pointer;padding:0;text-decoration:underline}.quiz-select{width:100%;padding:1rem;background:var(--bg-secondary);border:1px solid var(--border-color);color:var(--text-primary);border-radius:12px;font-size:var(--font-base);margin-bottom:2rem;appearance:none}.action-btn{width:100%;padding:1rem;border-radius:12px;border:none;font-weight:600;cursor:pointer;display:flex;align-items:center;justify-content:center;gap:.75rem;font-size:var(--font-base);transition:opacity .2s}.action-btn.primary{background:var(--accent-primary);color:#fff}.action-btn.success{background:var(--accent-success);color:#fff}.action-btn:hover{opacity:.9}.quiz-results-hero{padding:4rem 2rem;text-align:center;background:linear-gradient(180deg,var(--bg-secondary) 0%,transparent 100%);margin-bottom:2rem}.results-score-large{font-size:4rem;font-weight:800;color:var(--accent-success);display:block;margin:1rem 0}body.light-mode{--bg-primary: #f8fafc;--bg-secondary: #ffffff;--bg-card: rgba(0, 0, 0, .03);--bg-glass: rgba(255, 255, 255, .7);--text-primary: #0f172a;--text-secondary: #475569;--text-tertiary: #94a3b8;--border-color: #e2e8f0;--border-glass: #cbd5e1}body.light-mode .header-brand h1,body.light-mode .setup-title{background:linear-gradient(135deg,#0f172a,#475569);background-clip:text;-webkit-background-clip:text;-webkit-text-fill-color:transparent}.protect-cat{position:fixed;z-index:9999;width:64px;height:64px;pointer-events:none;filter:drop-shadow(2px 2px 0px rgba(0,0,0,.5));background-image:url(/assets/pixelated_cat_walk_strip-eqIlDi8z.png);background-size:256px 64px;background-repeat:no-repeat;image-rendering:pixelated}.protect-cat.walk{animation:catLegs .6s steps(4) infinite}.protect-cat.hit{background-position:0 0;animation:catHit .4s ease-in-out}@keyframes catLegs{0%{background-position:0 0}to{background-position:-256px 0}}@keyframes catHit{0%{transform:translate(-50%) scale(1)}50%{transform:translate(-50%,10px) scale(1.2)}to{transform:translate(-50%) scale(1)}}@keyframes pulse{0%{opacity:1}50%{opacity:.5}to{opacity:1}}@keyframes fadeIn{0%{opacity:0;transform:translateY(5px)}to{opacity:1;transform:translateY(0)}}.landing-container{min-height:100vh;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:2rem;background:radial-gradient(circle at top center,#1e293b,var(--bg-primary))}.landing-header{text-align:center;margin-bottom:3rem}.brand-large{display:flex;align-items:center;justify-content:center;gap:1rem;margin-bottom:1rem}.brand-large h1{font-size:4rem;font-weight:800;margin:0;background:linear-gradient(135deg,#fff,#3b82f6);background-clip:text;-webkit-background-clip:text;-webkit-text-fill-color:transparent}.brand-icon-large{color:var(--accent-primary);filter:drop-shadow(0 0 15px rgba(59,130,246,.6))}.landing-subtitle{font-size:var(--font-lg);color:var(--text-secondary);max-width:600px;margin:0 auto}.landing-auth-card{width:100%;max-width:400px;padding:2.5rem;margin-bottom:3rem;text-align:center}.landing-auth-card h2{margin-top:0;margin-bottom:1.5rem}.landing-auth-form{display:flex;flex-direction:column;gap:1rem}.auth-input-large{width:100%;padding:1rem;background:#0000004d;border:1px solid var(--border-color);border-radius:8px;color:#fff;font-size:var(--font-base)}.input-group{width:100%}.auth-switcher{margin-top:1.5rem;font-size:var(--font-sm);color:var(--text-secondary)}.text-btn{background:none;border:none;color:var(--accent-primary);cursor:pointer;text-decoration:underline;font-size:inherit;padding:0}.landing-welcome{text-align:center;margin-bottom:3rem}.landing-welcome h2{font-size:var(--font-xl);margin-bottom:.5rem}.topic-grid{display:flex;gap:2rem;flex-wrap:wrap;justify-content:center;width:100%;max-width:900px}.topic-card{flex:1;min-width:300px;padding:2rem;display:flex;flex-direction:column;align-items:center;text-align:center;transition:transform .3s,box-shadow .3s}.topic-card:hover{transform:translateY(-5px);box-shadow:0 10px 40px -10px #00000080;border-color:var(--accent-primary)}.card-icon{width:80px;height:80px;border-radius:50%;display:flex;align-items:center;justify-content:center;margin-bottom:1.5rem}.java-icon{background:#f59e0b1a;color:#f59e0b}.algo-icon{background:#10b9811a;color:#10b981}.theory-icon{background:#8b5cf61a;color:#8b5cf6}.topic-card h3{font-size:var(--font-xl);margin:0 0 1rem}.topic-card p{color:var(--text-secondary);margin-bottom:2rem;flex-grow:1}.card-actions{display:flex;flex-direction:column;gap:1rem;width:100%}.action-btn{padding:.8rem 1.5rem;border-radius:8px;font-weight:600;cursor:pointer;font-size:var(--font-base);transition:all .2s;display:flex;align-items:center;justify-content:center;gap:.5rem;width:100%}.action-btn.primary{background:var(--accent-primary);color:#fff;border:none}.action-btn.primary:hover{background:var(--accent-primary-hover)}.action-btn.secondary{background:transparent;border:1px solid var(--border-color);color:var(--text-primary)}.action-btn.secondary:hover{background:var(--bg-secondary)}.full-width{width:100%}.highlight{color:var(--accent-primary)}.landing-footer{margin-top:4rem;color:var(--text-tertiary);font-size:var(--font-xs)}.qc-image-container{margin:1.5rem 0;display:flex;justify-content:center;width:100%}.qc-image{max-width:100%;max-height:400px;border-radius:8px;border:1px solid var(--border-color);box-shadow:0 4px 6px -1px #0000004d;object-fit:contain;background:#fff}.qc-option-image{max-height:50px;margin-left:1rem;border-radius:4px;border:1px solid var(--border-color);background:#fff;cursor:pointer;transition:transform .2s}.qc-option-image:hover{transform:scale(1.5);z-index:10;box-shadow:0 4px 12px #0003}