*{box-sizing:border-box;margin:0;padding:0}html,body{height:100%;overflow:auto}body{font-family:DM Sans,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}#root{height:100%;overflow:auto}.app-container{min-height:100vh;background:#f0f4f8;width:100%;max-width:none;margin:0;padding:0;overflow:auto;display:flex;flex-direction:column}.mode-selection{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;padding:2rem;background:linear-gradient(135deg,#667eea,#764ba2)}.mode-selection h1{font-size:3rem;color:#fff;margin-bottom:3rem;text-align:center;text-shadow:0 2px 10px rgba(0,0,0,.2)}.mode-buttons{display:flex;flex-direction:column;gap:1.5rem;width:100%;max-width:500px}.mode-button{padding:2rem;font-size:1.5rem;font-weight:700;color:#1f2937;background:#fff;border:none;border-radius:20px;cursor:pointer;transition:all .3s ease;box-shadow:0 10px 30px #0000001a}.mode-button:hover{transform:translateY(-5px);box-shadow:0 15px 40px #00000026}.mode-button:active{transform:translateY(-2px)}.isee-level-selection{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;padding:2rem;background:linear-gradient(135deg,#f093fb,#f5576c)}.isee-level-selection h1{font-size:2.5rem;color:#fff;margin-bottom:2rem;text-align:center;text-shadow:0 2px 10px rgba(0,0,0,.2)}.level-buttons{display:flex;flex-direction:column;gap:1rem;width:100%;max-width:600px;margin-bottom:2rem}.level-button{padding:1.5rem 2rem;font-size:1.2rem;font-weight:600;color:#1f2937;background:#fff;border:none;border-radius:16px;cursor:pointer;transition:all .3s ease;box-shadow:0 4px 15px #0000001a;text-align:left}.level-button:hover{transform:translateY(-3px);box-shadow:0 8px 25px #00000026}.level-button:active{transform:translateY(-1px)}::-webkit-scrollbar{width:8px}::-webkit-scrollbar-track{background:#f1f5f9}::-webkit-scrollbar-thumb{background:#cbd5e1;border-radius:4px}::-webkit-scrollbar-thumb:hover{background:#94a3b8}::selection{background:#667eea4d;color:#1f2937}:focus-visible{outline:3px solid #667eea;outline-offset:2px}@keyframes slideIn{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}@media(max-width:768px){.mode-selection h1{font-size:2rem}.mode-button{padding:1.5rem;font-size:1.2rem}.isee-level-selection h1{font-size:2rem}.level-button{padding:1.2rem 1.5rem;font-size:1rem}}@media(max-width:480px){.mode-selection h1{font-size:1.5rem}.mode-button{padding:1.2rem;font-size:1rem}.isee-level-selection h1{font-size:1.5rem}.level-button{padding:1rem 1.2rem;font-size:.9rem}}.app-header{position:fixed;top:0;left:0;right:0;z-index:55;height:auto;padding-top:max(env(safe-area-inset-top),12px);padding-bottom:12px;padding-left:24px;padding-right:24px;background:#fffffff2;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-bottom:1px solid rgba(0,0,0,.08);box-shadow:0 1px 3px #00000014;display:flex;justify-content:space-between;align-items:center;gap:16px}.header-logo{flex:1;min-width:0}.header-logo h1{margin:0;font-family:Nunito,sans-serif;font-size:22px;font-weight:900;color:#1e293b;letter-spacing:-.3px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.header-auth{flex-shrink:0;display:flex;align-items:center}.app-container{padding-top:max(calc(env(safe-area-inset-top) + 60px),80px)}.login-button-container{position:relative}.login-sign-in-button{display:flex;align-items:center;gap:8px;padding:8px 16px;border:1px solid #e2e8f0;border-radius:10px;background:#fff;color:#475569;font-size:14px;font-weight:600;cursor:pointer;transition:all .15s ease;white-space:nowrap;box-shadow:0 1px 3px #0000000f}.login-sign-in-button:hover{background:#f8fafc;border-color:#667eea;color:#667eea;box-shadow:0 2px 6px #00000014}.login-user-button{display:flex;align-items:center;gap:8px;padding:4px 12px 4px 4px;border:1px solid #e2e8f0;border-radius:10px;background:#fff;cursor:pointer;transition:all .15s ease;max-width:200px;box-shadow:0 1px 3px #0000000f}.login-user-button:hover{border-color:#667eea;box-shadow:0 2px 6px #00000014}.login-avatar{width:28px;height:28px;border-radius:50%;object-fit:cover}.login-avatar-placeholder{width:28px;height:28px;border-radius:8px;background:#667eea;color:#fff;display:flex;align-items:center;justify-content:center;font-size:14px;font-weight:700}.login-display-name{font-size:13px;color:#475569;font-weight:500;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.login-dropdown{position:absolute;top:calc(100% + 6px);left:50%;transform:translate(-50%);background:#fff;border-radius:12px;box-shadow:0 4px 16px #0000001a;border:1px solid #e2e8f0;min-width:200px;z-index:100;overflow:hidden}.login-dropdown-item{display:block;width:100%;padding:12px 16px;border:none;background:none;font-size:14px;font-weight:500;cursor:pointer;text-align:left;transition:background .15s ease}.login-dropdown-item:hover{background:#f5f5f5}.google-button{display:flex;align-items:center;gap:10px;color:#3c4043;font-weight:500}.google-icon{flex-shrink:0}.sign-out-button{color:#d32f2f}.login-error{position:absolute;top:calc(100% + 6px);left:50%;transform:translate(-50%);background:#ffebee;color:#c62828;padding:8px 12px;border-radius:8px;font-size:12px;white-space:nowrap;z-index:100}@media(max-width:480px){.login-sign-in-button{padding:6px 12px;font-size:12px}.login-user-button{padding:3px 8px 3px 3px}.login-display-name{display:none}.login-dropdown{min-width:180px}}.grade-container{flex-grow:1;padding:24px 20px 20px;display:flex;flex-direction:column;align-items:center;min-height:100vh;box-sizing:border-box}.app-title{font-family:Nunito,sans-serif;font-size:38px;font-weight:900;color:#1e293b;margin:0 0 5px;text-align:center;letter-spacing:-.5px}.title{font-family:Nunito,sans-serif;font-size:22px;font-weight:700;color:#475569;margin-bottom:6px;text-align:center}.subtitle{font-size:15px;color:#94a3b8;margin-bottom:28px;text-align:center}.recent-progress-section{width:100%;max-width:600px;margin-top:28px;margin-bottom:28px;background:#fff;border-radius:16px;padding:20px;box-shadow:0 2px 12px #00000014;border:1px solid #e5e7eb}.recent-progress-header{margin-bottom:16px}.recent-progress-title{font-size:18px;font-weight:700;color:#1f2937;margin:0 0 6px}.progress-summary{display:flex;align-items:center;gap:6px;flex-wrap:wrap}.summary-stat{font-size:13px;color:#6b7280;font-weight:500}.summary-dot{font-size:13px;color:#d1d5db}.recent-progress-list{display:flex;flex-direction:column;gap:8px}.progress-row{display:flex;align-items:center;justify-content:space-between;padding:12px 14px;background:#f9fafb;border:1px solid #f3f4f6;border-radius:12px;cursor:pointer;transition:all .15s ease;width:100%;text-align:left}.progress-row:hover{background:#f3f4f6;border-color:#667eea;transform:translate(2px)}.progress-row-left{display:flex;align-items:center;gap:12px;min-width:0}.progress-row-grade-badge{font-size:11px;font-weight:700;color:#fff;background:linear-gradient(135deg,#667eea,#764ba2);padding:4px 8px;border-radius:6px;white-space:nowrap;flex-shrink:0}.progress-row-info{display:flex;flex-direction:column;gap:1px;min-width:0}.progress-row-topic{font-size:14px;font-weight:600;color:#1f2937;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.progress-row-time{font-size:11px;color:#9ca3af}.progress-row-right{display:flex;align-items:center;gap:10px;flex-shrink:0}.progress-row-level-badge{font-size:12px;font-weight:700;color:#667eea;background:#eef2ff;padding:3px 8px;border-radius:6px}.progress-row-accuracy{font-size:12px;font-weight:600;color:#6b7280;min-width:32px;text-align:right}.progress-row-bar{width:40px;height:4px;background:#e5e7eb;border-radius:2px;overflow:hidden}.progress-row-bar-fill{height:100%;background:linear-gradient(90deg,#667eea,#764ba2);border-radius:2px;transition:width .3s ease}.progress-row-arrow{font-size:14px;color:#d1d5db;transition:color .15s ease}.progress-row:hover .progress-row-arrow{color:#667eea}.delete-progress-button{margin-top:16px;padding:8px 16px;background:none;border:1px solid #e5e7eb;border-radius:8px;color:#9ca3af;font-size:12px;font-weight:500;cursor:pointer;transition:all .15s ease;width:100%}.delete-progress-button:hover{border-color:#ef4444;color:#ef4444;background:#fef2f2}.delete-confirm-overlay{position:fixed;inset:0;background:#00000080;display:flex;align-items:center;justify-content:center;z-index:1000;animation:fadeIn .2s ease}.delete-confirm-dialog{background:#fff;border-radius:16px;padding:28px;max-width:360px;width:90%;box-shadow:0 20px 40px #0003}.delete-confirm-title{font-size:18px;font-weight:700;color:#1f2937;margin:0 0 8px}.delete-confirm-text{font-size:14px;color:#6b7280;margin:0 0 20px;line-height:1.5}.delete-confirm-buttons{display:flex;gap:10px}.delete-confirm-cancel{flex:1;padding:10px;border:1px solid #e5e7eb;border-radius:10px;background:#fff;color:#374151;font-size:14px;font-weight:600;cursor:pointer}.delete-confirm-cancel:hover{background:#f9fafb}.delete-confirm-delete{flex:1;padding:10px;border:none;border-radius:10px;background:#ef4444;color:#fff;font-size:14px;font-weight:600;cursor:pointer}.delete-confirm-delete:hover{background:#dc2626}.delete-confirm-delete:disabled{opacity:.6;cursor:not-allowed}@media(max-width:480px){.progress-row-bar,.progress-row-accuracy{display:none}}.grade-groups{width:100%;max-width:600px;display:flex;flex-direction:column;gap:24px}.grade-group{border-radius:20px;padding:24px;background:#fff;box-shadow:0 1px 3px #0000000f,0 6px 16px #0000000a;transition:transform .2s ease,box-shadow .2s ease;border:1px solid rgba(0,0,0,.04)}.grade-group:hover{transform:translateY(-2px);box-shadow:0 2px 6px #00000014,0 12px 24px #0000000f}.grade-group.elementary{border-left:4px solid #22c55e}.grade-group.middle{border-left:4px solid #3b82f6}.grade-group.high{border-left:4px solid #a855f7}.group-header{margin-bottom:16px;text-align:left}.group-name{font-family:Nunito,sans-serif;font-size:18px;font-weight:800;margin:0 0 2px;color:#1e293b}.group-description{font-size:13px;margin:0;color:#94a3b8}.grade-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(80px,1fr));gap:10px}.grade-button{padding:14px 8px;border-radius:16px;display:flex;flex-direction:column;align-items:center;justify-content:center;border:none;cursor:pointer;color:#fff;font-weight:700;transition:transform .15s ease,box-shadow .15s ease;min-height:72px;box-shadow:0 2px 8px #0000001a}.grade-button .grade-number{font-family:Nunito,sans-serif;font-size:26px;font-weight:900;line-height:1}.grade-button .grade-label{font-size:11px;font-weight:500;opacity:.85;margin-top:4px}.grade-button.elementary{background:#22c55e}.grade-button.elementary:hover{transform:translateY(-2px);box-shadow:0 6px 16px #22c55e59}.grade-button.middle{background:#3b82f6}.grade-button.middle:hover{transform:translateY(-2px);box-shadow:0 6px 16px #3b82f659}.grade-button.high{background:#a855f7}.grade-button.high:hover{transform:translateY(-2px);box-shadow:0 6px 16px #a855f759}.grade-button:active{transform:scale(.95);box-shadow:0 1px 4px #0000001a}@media(max-width:480px){.grade-groups{padding:0 10px}.grade-group{padding:16px}.grade-grid{grid-template-columns:repeat(3,1fr)}.grade-button{min-height:60px;padding:10px 6px}.grade-button .grade-number{font-size:20px}.grade-button .grade-label{font-size:10px}}@media(min-width:481px){.elementary .grade-grid{grid-template-columns:repeat(6,1fr)}.middle .grade-grid{grid-template-columns:repeat(3,1fr)}.high .grade-grid{grid-template-columns:repeat(4,1fr)}}.topic-container{padding:20px;padding-top:max(calc(env(safe-area-inset-top) + 16px),60px);min-height:100vh;max-width:1000px;margin:0 auto;background:#f0f4f8;box-sizing:border-box}.topic-header{margin-bottom:30px;text-align:center}.topic-container .back-button{background:#fff;padding:10px 20px;border-radius:10px;border:1px solid #e2e8f0;cursor:pointer;color:#475569;font-size:14px;font-weight:600;transition:all .15s ease;box-shadow:0 1px 3px #0000000f;display:inline-flex;align-items:center;gap:8px}.topic-container .back-button:hover{transform:translateY(-1px);border-color:#667eea;color:#667eea;box-shadow:0 2px 6px #00000014}.topic-container .back-button:active{transform:scale(.97)}.grade-title{font-family:Nunito,sans-serif;font-size:32px;font-weight:900;color:#1e293b;text-align:center;margin:20px 0 10px;letter-spacing:-.5px}.topic-subtitle{font-size:18px;color:#6b7280;text-align:center;margin-bottom:10px;font-weight:500}.topics-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px;margin-top:25px;padding:10px}@media(min-width:769px){.topics-grid{grid-template-columns:repeat(3,1fr)}}.topic-card{background:#fff;border-radius:16px;padding:24px;cursor:pointer;box-shadow:0 1px 3px #0000000f,0 4px 12px #0000000a;transition:all .2s ease;border:1px solid rgba(0,0,0,.04);border-left:4px solid #667eea;position:relative;overflow:hidden}@media(hover:hover){.topic-card:hover{transform:translateY(-3px);box-shadow:0 2px 6px #00000014,0 12px 24px #0000000f;border-left-color:#667eea}.topic-card:hover .topic-arrow{color:#667eea;transform:translateY(-50%) translate(3px)}}.topic-card:active{transform:scale(.98)}.topic-icon{font-size:32px;margin-bottom:12px;display:block}.topic-name{font-size:20px;font-weight:700;color:#1f2937;margin-bottom:10px;margin-top:0;display:flex;align-items:center;gap:10px}.topic-description{font-size:14px;color:#6b7280;margin:0;line-height:1.6}.topic-arrow{position:absolute;right:20px;top:50%;transform:translateY(-50%);font-size:20px;color:#d1d5db;transition:all .3s ease}.topic-level-badge{display:inline-flex;align-items:center;justify-content:center;background:#fef3c7;color:#d97706;font-size:11px;font-weight:700;padding:2px 8px;border-radius:6px;white-space:nowrap;border:1px solid #fde68a}.no-topics{text-align:center;padding:60px 40px;background:#fff;border-radius:20px;box-shadow:0 4px 20px #00000014}.no-topics p{font-size:18px;color:#6b7280;margin:0}.topic-count{display:inline-block;background:#eef2ff;color:#667eea;font-size:12px;font-weight:600;padding:6px 14px;border-radius:8px;margin-bottom:20px;border:1px solid #c7d2fe}@media(max-width:768px){.topics-grid{grid-template-columns:repeat(2,1fr);gap:12px;padding:6px}.topic-container{padding:15px}.grade-title{font-size:28px}.topic-card{padding:16px}.topic-icon{font-size:26px;margin-bottom:8px}.topic-name{font-size:15px;margin-bottom:6px}.topic-description{font-size:12px}.topic-arrow{display:none}}@media(max-width:480px){.topics-grid{grid-template-columns:repeat(2,1fr);gap:10px;padding:4px}.topic-card{padding:14px 12px;border-radius:16px;min-height:100px;-webkit-tap-highlight-color:rgba(102,126,234,.15);touch-action:manipulation}.topic-card:active{transform:scale(.97);background-color:#f8fafc}.topic-icon{font-size:22px;margin-bottom:6px}.topic-name{font-size:13px;gap:4px}.topic-description{font-size:11px;line-height:1.4;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}.topic-container .back-button{padding:10px 18px;font-size:14px;min-height:44px;touch-action:manipulation;-webkit-tap-highlight-color:transparent}}.question-container-wrapper{flex-grow:1;padding:20px;padding-top:max(calc(env(safe-area-inset-top) + 16px),60px);min-height:100vh;background:#f0f4f8;display:flex;flex-direction:column;overflow:auto;box-sizing:border-box}.loading-container{display:flex;flex-direction:column;justify-content:center;align-items:center;min-height:100vh;gap:20px}.loading-text{font-size:20px;color:#475569;font-weight:600}.loading-spinner{width:50px;height:50px;border:4px solid #e2e8f0;border-top-color:#667eea;border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.header{margin-bottom:12px;max-width:800px;margin-left:auto;margin-right:auto;width:100%;flex-shrink:0}.nav-buttons{display:flex;gap:8px;margin-bottom:8px;flex-wrap:wrap;align-items:center}.back-button{background:#fff;padding:8px 14px;border-radius:10px;border:1px solid #e2e8f0;cursor:pointer;color:#475569;font-size:13px;font-weight:600;transition:all .15s ease;display:inline-flex;align-items:center;gap:4px;box-shadow:0 1px 3px #0000000f}.back-button:hover{background:#f8fafc;border-color:#667eea;color:#667eea;transform:translateY(-1px);box-shadow:0 2px 6px #00000014}.topics-button{background:#fff}.topics-button:hover{background:#f8fafc}.grade-title{font-family:Nunito,sans-serif;font-size:24px;font-weight:800;color:#1e293b;text-align:center;margin-bottom:8px}.stats-container{display:flex;justify-content:center;gap:20px;padding:10px 20px;background:#fff;border-radius:12px;border:1px solid #e2e8f0;box-shadow:0 1px 3px #0000000f}.stats-text{font-size:15px;font-weight:700;color:#475569;display:flex;align-items:center;gap:6px}.stats-icon{font-size:16px}.question-container{background:#fff;padding:24px;border-radius:20px;box-shadow:0 1px 3px #0000000f,0 6px 16px #0000000a;border:1px solid rgba(0,0,0,.04);max-width:800px;margin:0 auto;width:100%;animation:slideUp .5s ease;flex:0 0 auto;display:flex;flex-direction:column}@keyframes slideUp{0%{opacity:0;transform:translateY(30px)}to{opacity:1;transform:translateY(0)}}.question-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;gap:10px;flex-shrink:0}.question-text{font-size:20px;font-weight:700;color:#1f2937;line-height:1.4;flex:1;margin:0}.ai-badge{display:inline-flex;align-items:center;gap:6px;font-size:13px;padding:8px 14px;border-radius:20px;font-weight:600;white-space:nowrap;flex-shrink:0}.ai-badge.ai-generated{background:#ecfdf5;color:#059669;border:1px solid #a7f3d0}.ai-badge.random-generated{background:#fffbeb;color:#d97706;border:1px solid #fde68a}.options-container{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin-bottom:12px;flex:1;align-content:start}.keyboard-hint{font-size:12px;color:#9ca3af;text-align:center;margin-bottom:10px;font-weight:500;grid-column:1 / -1}.option-button{background:#f8fafc;padding:14px 16px;border-radius:12px;border:2px solid #e2e8f0;cursor:pointer;color:#1f2937;font-size:16px;font-weight:700;transition:all .15s ease;display:flex;align-items:center;gap:10px;text-align:left}.option-button:hover:not(:disabled){background:#667eea;border-color:#667eea;color:#fff;transform:translateY(-2px);box-shadow:0 4px 12px #667eea40}.option-button:active:not(:disabled){transform:scale(.97);box-shadow:none}.option-button:disabled{cursor:not-allowed;opacity:.7}.correct-option{background:#10b981!important;border-color:#10b981!important;color:#fff!important;animation:correctPulse .5s ease}@keyframes correctPulse{0%,to{transform:scale(1)}50%{transform:scale(1.02)}}.option-number{display:inline-flex;align-items:center;justify-content:center;width:26px;height:26px;background:#0000001a;border-radius:6px;font-size:12px;font-weight:700;flex-shrink:0}.option-button:hover:not(:disabled) .option-number{background:#fff3}.correct-option .option-number{background:#fff3}.input-container{margin-bottom:12px;flex-shrink:0}.answer-input{border:2px solid #e2e8f0;border-radius:12px;padding:14px 18px;font-size:20px;font-weight:600;text-align:center;margin-bottom:12px;background:#f8fafc;width:100%;box-sizing:border-box;transition:all .15s ease;color:#1f2937}.answer-input:focus{outline:none;border-color:#667eea;box-shadow:0 0 0 4px #667eea33;background:#fff}.answer-input::placeholder{color:#9ca3af;font-weight:500;font-size:16px}.submit-button{background:#ef4444;padding:14px 24px;border-radius:12px;border:none;cursor:pointer;color:#fff;font-size:16px;font-weight:700;width:100%;transition:all .15s ease;box-shadow:0 2px 8px #ef444433}.submit-button:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 4px 12px #ef44444d}.submit-button:active:not(:disabled){transform:scale(.97);box-shadow:none}.disabled-button{background:#d1d5db!important;cursor:not-allowed!important;box-shadow:none!important}.feedback-container{margin-top:12px;padding:12px 16px;border-radius:12px;text-align:center;animation:fadeInUp .3s ease;flex-shrink:0}@keyframes fadeInUp{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.feedback-text{font-size:16px;font-weight:700;text-align:center;margin:0;display:flex;align-items:center;justify-content:center;gap:8px}.correct-feedback{color:#059669;background:#ecfdf5;border:1px solid #a7f3d0}.incorrect-feedback{color:#dc2626;background:#fef2f2;border:1px solid #fecaca}.explanation-container{margin-top:12px;padding-top:12px;border-top:1px solid rgba(220,38,38,.2)}.explanation-label{font-size:13px;font-weight:600;color:#92400e;margin:0 0 6px;text-align:left}.explanation-text{font-family:SF Mono,Fira Code,Consolas,monospace;font-size:14px;font-weight:600;color:#1f2937;background:#fff9;padding:10px 14px;border-radius:8px;margin:0;white-space:pre-wrap;line-height:1.6;text-align:left}.next-button{background:#667eea;padding:14px 24px;border-radius:12px;border:none;cursor:pointer;color:#fff;font-size:16px;font-weight:700;margin-top:12px;width:100%;transition:all .15s ease;box-shadow:0 2px 8px #667eea33;display:flex;align-items:center;justify-content:center;gap:8px;flex-shrink:0}.next-button:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 4px 12px #667eea4d}.next-button:active:not(:disabled){transform:scale(.97);box-shadow:none}.next-button:disabled{opacity:.7;cursor:not-allowed}.keyboard-shortcut{font-size:12px;color:#ffffffb3;font-weight:500;background:#ffffff26;padding:4px 10px;border-radius:8px}.progress-container{margin-top:12px;padding-top:12px;border-top:1px solid #f1f5f9;flex-shrink:0}.progress-label{font-size:12px;color:#6b7280;font-weight:600;margin-bottom:6px;display:flex;justify-content:space-between}.progress-bar{height:6px;background:#e5e7eb;border-radius:6px;overflow:hidden}.progress-fill{height:100%;background:linear-gradient(90deg,#667eea,#764ba2);border-radius:6px;transition:width .5s ease}.level-progress-fill{background:linear-gradient(90deg,#f59e0b,#ef4444)!important}.level-up-overlay{position:fixed;inset:0;background:#0009;display:flex;align-items:center;justify-content:center;z-index:1000;animation:fadeIn .3s ease}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}.level-up-content{background:#fff;border-radius:24px;padding:40px;text-align:center;animation:levelUpBounce .5s cubic-bezier(.175,.885,.32,1.275);box-shadow:0 25px 50px #00000040;max-width:320px;width:90%}@keyframes levelUpBounce{0%{opacity:0;transform:scale(.5) translateY(40px)}to{opacity:1;transform:scale(1) translateY(0)}}.level-up-icon{font-size:64px;margin-bottom:12px}.level-up-title{font-family:Nunito,sans-serif;font-size:32px;font-weight:900;color:#f59e0b;margin:0 0 8px}.level-up-text{font-size:20px;font-weight:700;color:#1f2937;margin:0 0 4px}.level-up-subtext{font-size:14px;color:#6b7280;margin:0}.confetti-piece{position:fixed;top:-10px;z-index:1001;opacity:1;animation:confettiFall linear forwards}@keyframes confettiFall{0%{transform:translateY(0) translate(0) rotate(0);opacity:1}25%{transform:translateY(25vh) translate(15px) rotate(180deg)}50%{transform:translateY(50vh) translate(-10px) rotate(360deg)}75%{transform:translateY(75vh) translate(20px) rotate(540deg);opacity:1}to{transform:translateY(100vh) translate(-5px) rotate(720deg);opacity:0}}@media(max-width:768px){.question-container-wrapper{padding:12px;padding-top:max(calc(env(safe-area-inset-top) + 16px),60px);padding-bottom:max(12px,env(safe-area-inset-bottom))}.header{margin-bottom:8px}.nav-buttons{gap:6px;margin-bottom:6px}.back-button{padding:6px 12px;font-size:12px}.grade-title{font-size:20px;margin-bottom:6px}.stats-container{gap:12px;padding:8px 14px}.stats-text{font-size:13px}.stats-icon{font-size:14px}.question-container{padding:16px;border-radius:16px}.question-header{margin-bottom:12px}.question-text{font-size:18px}.ai-badge{font-size:11px;padding:5px 10px}.options-container{gap:8px}.option-button{padding:12px 14px;font-size:15px;border-radius:10px}.option-number{width:24px;height:24px;font-size:11px}.answer-input{padding:12px 14px;font-size:18px;border-radius:10px}.submit-button,.next-button{padding:12px 20px;font-size:15px;border-radius:10px}.feedback-container{padding:10px 12px;margin-top:10px}.feedback-text{font-size:14px}.progress-container{margin-top:10px;padding-top:10px}.progress-label{font-size:11px}.progress-bar{height:5px}}@media(max-width:480px){.question-container-wrapper{padding:10px;padding-top:max(calc(env(safe-area-inset-top) + 16px),60px);padding-bottom:max(10px,env(safe-area-inset-bottom))}.header{margin-bottom:6px}.nav-buttons{flex-direction:row;justify-content:flex-start}.back-button{padding:5px 10px;font-size:11px;border-radius:15px}.grade-title{font-size:18px;margin-bottom:4px}.stats-container{padding:6px 12px;border-radius:12px}.stats-text{font-size:12px}.question-container{padding:14px;border-radius:14px}.question-header{flex-direction:row;align-items:center;margin-bottom:10px;gap:8px}.question-text{font-size:16px;line-height:1.3}.ai-badge{font-size:10px;padding:4px 8px}.keyboard-hint{display:none}.options-container{grid-template-columns:repeat(2,1fr);gap:6px}.option-button{padding:10px 12px;font-size:14px;gap:6px}.option-number{width:22px;height:22px;font-size:10px}.answer-input{padding:10px 12px;font-size:16px;margin-bottom:10px}.submit-button,.next-button{padding:10px 16px;font-size:14px;margin-top:8px}.feedback-container{padding:8px 10px;margin-top:8px;border-radius:10px}.feedback-text{font-size:13px;gap:6px}.keyboard-shortcut{display:none}.progress-container{margin-top:8px;padding-top:8px}.progress-label{font-size:10px;margin-bottom:4px}.progress-bar{height:4px}}@media(max-height:700px){.question-container-wrapper{padding:8px}.header{margin-bottom:4px}.grade-title{font-size:16px;margin-bottom:4px}.stats-container{padding:5px 10px}.question-container{padding:12px}.question-header{margin-bottom:8px}.question-text{font-size:15px}.options-container{gap:5px}.option-button{padding:8px 10px;font-size:13px}.feedback-container{padding:6px 8px;margin-top:6px}.feedback-text{font-size:12px}.next-button{padding:8px 14px;font-size:13px;margin-top:6px}.progress-container{margin-top:6px;padding-top:6px}}:root{font-family:Inter,system-ui,Avenir,Helvetica,Arial,sans-serif;line-height:1.5;font-weight:400;color-scheme:light dark;color:#ffffffde;background-color:#242424;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;-webkit-text-size-adjust:100%}*{box-sizing:border-box}body{margin:0;display:flex;place-items:center;min-width:320px;min-height:100vh;background-color:#f0f8ff}#root{max-width:1280px;margin:0 auto;padding:2rem;text-align:center;width:100%}
