:root{--primary-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);--bg-dark: #0f172a;--sidebar-bg: rgba(30, 41, 59, .7);--card-bg: rgba(30, 41, 59, .8);--text-main: #f8fafc;--text-muted: #94a3b8;--accent: #38bdf8;--success: #22c55e;--error: #ef4444;--border: rgba(255, 255, 255, .1);--shadow: 0 10px 25px -5px rgba(0, 0, 0, .3);--modal-bg: #1e293b;--transition: .3s ease}body.light-theme{--bg-dark: #f1f5f9;--sidebar-bg: rgba(255, 255, 255, .8);--card-bg: #ffffff;--text-main: #0f172a;--text-muted: #475569;--border: rgba(0, 0, 0, .1);--shadow: 0 4px 6px -1px rgba(0, 0, 0, .1), 0 2px 4px -1px rgba(0, 0, 0, .06);--modal-bg: #ffffff}*{box-sizing:border-box;margin:0;padding:0;font-family:Inter,-apple-system,system-ui,sans-serif}html,body{background:var(--bg-dark);color:var(--text-main);overflow:hidden;height:100%;overscroll-behavior:none!important}.app-container{display:flex;height:100vh;width:100vw}.sidebar{width:320px;background:var(--sidebar-bg);-webkit-backdrop-filter:blur(20px);backdrop-filter:blur(20px);border-right:1px solid var(--border);display:flex;flex-direction:column;padding:24px;z-index:1001}.logo-area h1{font-size:1.5rem;font-weight:800;background:var(--primary-gradient);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;margin-bottom:30px}.folder-list{list-style:none}.folder-item{padding:12px 14px;border-radius:8px;cursor:pointer;transition:all .2s;color:var(--text-muted);font-size:.9rem;margin-bottom:4px;border:1px solid transparent}.folder-item:hover{background:#ffffff0d;color:var(--text-main);border-color:var(--border)}.folder-item.active{background:var(--primary-gradient);color:#fff}body.light-theme .folder-item.active{background:#a5f3fc!important;color:#000!important}.main-content{flex:1;display:flex;flex-direction:column;height:100vh;overflow-y:auto;position:relative;padding-bottom:250px;overscroll-behavior:contain!important}.header-stats{position:sticky;top:0;z-index:1000;background:var(--bg-dark);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);padding:15px 40px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--border)}.q-badge{background:#6366f11a;color:#818cf8;padding:6px 14px;border-radius:20px;font-weight:700}.card{background:var(--card-bg);border:1px solid var(--border);border-radius:24px;padding:30px 40px;box-shadow:var(--shadow);width:95%;max-width:1100px;margin:30px auto}.quiz-question{font-size:1.1rem;line-height:1.6;margin-bottom:25px;word-break:break-word;overflow-wrap:break-word}.choice-item{padding:16px 20px;background:#ffffff08;border:1px solid var(--border);border-radius:12px;cursor:pointer;margin-bottom:10px;transition:.2s;font-size:.95rem}.choice-item:hover{background:#ffffff0f}.choice-item.selected{background:#6366f11a;border-color:#6366f1}.choice-item.correct{background:#22c55e26!important;border-color:#22c55e!important;color:#4ade80!important}.choice-item.incorrect{background:#ef444426!important;border-color:#ef4444!important;color:#f87171!important}.feedback-panel{margin-top:50px;display:flex;flex-direction:column;gap:10px}.feedback-badge{display:inline-block;padding:8px 24px;border-radius:12px;font-weight:800;font-size:.9rem;letter-spacing:.05em;width:fit-content;box-shadow:0 4px 12px #0003}.feedback-badge.correct{background:var(--success);color:#fff}.feedback-badge.incorrect{background:var(--error);color:#fff}.explanation-title{text-transform:uppercase;letter-spacing:.1em;color:var(--text-muted);font-size:.75rem;margin-top:15px;margin-bottom:8px}.explanation-text{line-height:1.7;color:var(--text-muted);font-size:.95rem;word-break:break-word;overflow-wrap:break-word}.footer-fixed-controls{position:fixed;bottom:0;right:0;width:calc(100% - 320px);padding:20px 40px;display:flex;justify-content:center;background:var(--bg-dark);-webkit-backdrop-filter:blur(15px);backdrop-filter:blur(15px);border-top:1px solid var(--border);z-index:1000}.bottom-nav{display:flex;gap:30px;align-items:center;justify-content:center}.nav-btn{width:65px;height:65px;border-radius:50%;border:1px solid var(--border);background:var(--card-bg);color:var(--text-main);font-size:1.5rem;cursor:pointer;display:flex;align-items:center;justify-content:center;box-shadow:var(--shadow);transition:transform .2s,background .2s;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.nav-btn:hover{transform:scale(1.1);background:#ffffff1a}.nav-btn:disabled{opacity:.3;cursor:not-allowed}body.light-theme .nav-btn{background:#fff;color:#000}.score-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(45px,1fr));gap:12px;margin-top:15px}.modal-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#000000b3;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);display:flex;align-items:center;justify-content:center;z-index:2000}.modal-content{background:var(--modal-bg);border:1px solid var(--border);border-radius:20px;padding:30px;width:90%;max-width:800px;box-shadow:var(--shadow)}.side-input{width:100%;border:1px solid var(--border);background:#ffffff0d;color:var(--text-main);padding:12px;border-radius:8px;font-size:1rem;outline:none}.icon-side-btn{flex:1;width:100%;min-height:55px;border-radius:12px;border:1px solid var(--border);background:#ffffff08;color:var(--text-main);cursor:pointer;display:flex;flex-direction:column;align-items:center;justify-content:center;transition:.2s;font-size:1.1rem}@media (max-width: 768px){.sidebar{position:fixed;left:-100%;top:0;bottom:0;width:280px;z-index:2100;transition:.3s ease;background:var(--modal-bg);box-shadow:10px 0 30px #00000080}.sidebar.open{left:0}.main-content{padding-bottom:180px}.footer-fixed-controls{width:100%;padding:15px 20px}.bottom-nav{gap:15px}.nav-btn{width:55px;height:55px;font-size:1.2rem}.card{width:96%;padding:24px 20px;margin:10px auto;border-radius:16px}.quiz-question{font-size:.95rem;margin-bottom:20px;text-align:justify;text-justify:inter-word;line-height:1.5}.choice-item{font-size:.82rem;padding:14px 18px;text-align:justify;text-justify:inter-word;line-height:1.4}.explanation-text{font-size:.82rem;text-align:justify;text-justify:inter-word;line-height:1.5}.q-badge{font-size:.75rem;padding:4px 10px}.header-stats{padding:10px 15px}.mobile-menu-btn{width:35px;height:35px;font-size:1rem}.modal-content{padding:20px;max-height:75vh;overflow-y:auto}.score-grid{grid-template-columns:repeat(auto-fill,minmax(38px,1fr));gap:8px}.sidebar-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#0009;-webkit-backdrop-filter:blur(5px);backdrop-filter:blur(5px);z-index:2050}}.landing-container{animation:fadeIn .8s cubic-bezier(.4,0,.2,1);text-align:center;overflow-y:auto}.badge-grid{padding:20px}.lib-badge{position:relative;transition:all .4s cubic-bezier(.175,.885,.32,1.275)}.lib-badge:hover{transform:translateY(-12px) scale(1.05);border-color:var(--accent);box-shadow:0 30px 60px #00000080;background:#ffffff0d}.lib-badge button{transition:.3s}.lib-badge:hover button{transform:scale(1.1);box-shadow:0 0 20px #ffffff4d}@keyframes fadeIn{0%{opacity:0;transform:translateY(30px) scale(.95)}to{opacity:1;transform:translateY(0) scale(1)}}@media (max-width: 768px){.badge-grid{grid-template-columns:1fr!important;gap:20px!important;padding:10px!important}.landing-container{padding:20px!important;justify-content:flex-start!important}.landing-container h1{font-size:2.2rem!important;margin-top:40px}.lib-badge{padding:30px!important}}@media (min-width: 769px){.mobile-menu-btn,.mobile-close{display:none}}.mobile-close{display:none}.score-item{aspect-ratio:1;border:1px solid var(--border);border-radius:10px;display:flex;align-items:center;justify-content:center;font-weight:700;cursor:pointer;transition:.2s;background:#ffffff08}.score-item.correct{background:var(--success)!important;color:#fff;border:none}.score-item.incorrect{background:var(--error)!important;color:#fff;border:none}.score-item.current{border:2px solid var(--accent);box-shadow:0 0 10px var(--accent)}.side-btn.primary{background:var(--primary-gradient);border:none;color:#fff;padding:12px 20px;border-radius:12px;font-weight:700;cursor:pointer;transition:.2s}.toast{padding:12px 24px;border-radius:12px;background:var(--modal-bg);border:1px solid var(--border);color:var(--text-main);font-weight:600;box-shadow:var(--shadow);animation:slideIn .3s ease-out}@keyframes slideIn{0%{transform:translate(50%);opacity:0}to{transform:translate(0);opacity:1}}