:root{--color-bg: #F5F4FF;--color-surface: #FFFFFF;--color-surface-2: #F0EFFE;--color-border: #E0DCFC;--color-text-1: #1A1744;--color-text-2: #4A4580;--color-text-3: #8B88B0;--color-primary: #4F46E5;--color-primary-light: #EEF2FF;--color-primary-hover: #4338CA;--color-fraction-a: #2563EB;--color-fraction-a-light: #DBEAFE;--color-fraction-b: #EA580C;--color-fraction-b-light: #FFEDD5;--color-success: #16A34A;--color-success-light: #DCFCE7;--color-warning: #D97706;--color-warning-light: #FEF3C7;--font-display: "Nunito", system-ui, sans-serif;--font-body: "Nunito Sans", system-ui, sans-serif;--radius-sm: 8px;--radius-md: 12px;--radius-lg: 20px;--radius-xl: 28px;--shadow-sm: 0 1px 3px rgba(79, 70, 229, .08);--shadow-md: 0 4px 16px rgba(79, 70, 229, .12);--shadow-lg: 0 8px 32px rgba(79, 70, 229, .16)}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html{font-size:18px}body{font-family:var(--font-body);background:var(--color-bg);color:var(--color-text-1);min-height:100vh;line-height:1.5;-webkit-font-smoothing:antialiased}#root{min-height:100vh;display:flex;flex-direction:column}h1,h2,h3{font-family:var(--font-display);font-weight:800;line-height:1.2}h1{font-size:2.2rem}h2{font-size:1.7rem}h3{font-size:1.3rem}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font-family:var(--font-display);font-weight:700;font-size:1rem;padding:14px 28px;border-radius:var(--radius-md);border:none;cursor:pointer;transition:all .15s ease;min-height:52px;min-width:52px;text-decoration:none}.btn:active{transform:scale(.97)}.btn:disabled{opacity:.5;cursor:not-allowed}.btn:disabled:active{transform:none}.btn-primary{background:var(--color-primary);color:#fff;box-shadow:0 4px 14px #4f46e559}.btn-primary:hover:not(:disabled){background:var(--color-primary-hover);box-shadow:0 6px 20px #4f46e573;transform:translateY(-1px)}.btn-ghost{background:transparent;color:var(--color-text-2);border:2px solid var(--color-border)}.btn-ghost:hover:not(:disabled){background:var(--color-surface);border-color:var(--color-primary);color:var(--color-primary)}.btn-large{font-size:1.2rem;padding:18px 36px;min-height:64px}.card{background:var(--color-surface);border-radius:var(--radius-lg);border:1.5px solid var(--color-border);padding:28px;box-shadow:var(--shadow-sm)}.answer-btn{display:flex;align-items:center;justify-content:center;padding:20px 32px;border-radius:var(--radius-md);border:2.5px solid var(--color-border);background:var(--color-surface);font-family:var(--font-display);font-weight:800;font-size:1.1rem;color:var(--color-text-1);cursor:pointer;transition:all .15s ease;min-height:64px;min-width:64px}.answer-btn:hover:not(:disabled){border-color:var(--color-primary);background:var(--color-primary-light);color:var(--color-primary);transform:translateY(-2px);box-shadow:var(--shadow-md)}.answer-btn:active:not(:disabled){transform:translateY(0)}.answer-btn.selected-correct{border-color:var(--color-success);background:var(--color-success-light);color:var(--color-success)}.answer-btn.selected-wrong{border-color:var(--color-warning);background:var(--color-warning-light);color:var(--color-warning)}.answer-btn:disabled{cursor:default}.progress-bar{height:8px;background:var(--color-surface-2);border-radius:100px;overflow:hidden}.progress-fill{height:100%;background:var(--color-primary);border-radius:100px;transition:width .4s ease}.fraction{display:inline-flex;flex-direction:column;align-items:center;font-family:var(--font-display);font-weight:900;line-height:1;gap:3px}.fraction-numerator{font-size:1.8rem}.fraction-bar{width:100%;height:3px;border-radius:2px;min-width:28px}.fraction-denominator{font-size:1.8rem}.fraction-a .fraction-bar{background:var(--color-fraction-a)}.fraction-b .fraction-bar{background:var(--color-fraction-b)}.feedback-box{border-radius:var(--radius-md);padding:20px 24px;border:2px solid;font-size:1rem;line-height:1.6}.feedback-box.success{background:var(--color-success-light);border-color:var(--color-success);color:#14532d}.feedback-box.try-again{background:var(--color-warning-light);border-color:var(--color-warning);color:#78350f}.session-dot{width:52px;height:52px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-family:var(--font-display);font-weight:800;font-size:1.1rem;border:3px solid;transition:all .2s ease;cursor:pointer;position:relative}.session-dot.done{background:var(--color-primary);border-color:var(--color-primary);color:#fff}.session-dot.active{background:#fff;border-color:var(--color-primary);color:var(--color-primary);box-shadow:0 0 0 4px var(--color-primary-light)}.session-dot.locked{background:var(--color-surface-2);border-color:var(--color-border);color:var(--color-text-3);cursor:not-allowed}.phase-nav{display:flex;align-items:center;gap:8px;font-family:var(--font-display);font-weight:700;font-size:.85rem}.phase-step{display:flex;align-items:center;gap:6px;padding:6px 14px;border-radius:100px;color:var(--color-text-3)}.phase-step.done{color:var(--color-success)}.phase-step.active{background:var(--color-primary-light);color:var(--color-primary)}.phase-arrow{color:var(--color-border);font-size:1rem}@keyframes fadeIn{0%{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}@keyframes popIn{0%{transform:scale(.8);opacity:0}60%{transform:scale(1.05)}to{transform:scale(1);opacity:1}}@keyframes slideRight{0%{transform:translate(-12px);opacity:0}to{transform:translate(0);opacity:1}}@keyframes bounce{0%,to{transform:translateY(0)}50%{transform:translateY(-8px)}}@keyframes shimmer{0%{background-position:-200% center}to{background-position:200% center}}.animate-fade-in{animation:fadeIn .35s ease forwards}.animate-pop-in{animation:popIn .4s cubic-bezier(.34,1.56,.64,1) forwards}.animate-slide-right{animation:slideRight .3s ease forwards}.animate-bounce{animation:bounce 1s ease-in-out infinite}@media (prefers-reduced-motion: reduce){*,*:before,*:after{animation-duration:.01ms!important;transition-duration:.01ms!important}}.container{max-width:900px;margin:0 auto;padding:0 24px;width:100%}.container-narrow{max-width:640px;margin:0 auto;padding:0 24px;width:100%}.stack{display:flex;flex-direction:column}.stack-sm{gap:8px}.stack-md{gap:16px}.stack-lg{gap:28px}.row{display:flex;flex-direction:row;align-items:center}.row-gap-sm{gap:8px}.row-gap-md{gap:16px}.row-gap-lg{gap:24px}.text-center{text-align:center}.text-muted{color:var(--color-text-2)}.text-faint{color:var(--color-text-3)}.text-sm{font-size:.9rem}.text-lg{font-size:1.1rem}.text-xl{font-size:1.3rem}::-webkit-scrollbar{width:6px}::-webkit-scrollbar-track{background:transparent}::-webkit-scrollbar-thumb{background:var(--color-border);border-radius:3px}.app-bar{background:var(--color-surface);border-bottom:1.5px solid var(--color-border);padding:14px 24px;display:flex;align-items:center;justify-content:space-between;position:sticky;top:0;z-index:100;box-shadow:0 1px 8px #4f46e50f}.app-logo{font-family:var(--font-display);font-weight:900;font-size:1.35rem;color:var(--color-primary);display:flex;align-items:center;gap:8px}.mastery-badge{display:inline-flex;align-items:center;gap:6px;padding:6px 16px;border-radius:100px;font-family:var(--font-display);font-weight:800;font-size:.85rem}.badge-achieved{background:var(--color-success-light);color:var(--color-success);border:2px solid #86efac}.badge-in-progress{background:var(--color-primary-light);color:var(--color-primary);border:2px solid #c7d2fe}.badge-not-started{background:var(--color-surface-2);color:var(--color-text-3);border:2px solid var(--color-border)}.score-circle{width:80px;height:80px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-family:var(--font-display);font-weight:900;font-size:1.5rem;border:4px solid}.score-pass{background:var(--color-success-light);border-color:var(--color-success);color:var(--color-success)}.score-near{background:var(--color-warning-light);border-color:var(--color-warning);color:var(--color-warning)}.score-low{background:#fff1f2;border-color:#f43f5e;color:#e11d48}.divider{height:1.5px;background:var(--color-border);border:none;border-radius:1px}.star{color:#fbbf24;font-size:1.5rem}@media (max-width: 640px){html{font-size:16px}.container,.container-narrow{padding:0 16px}h1{font-size:1.8rem}h2{font-size:1.4rem}}