*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
:root{
  --primary:#6c3dff;--primary-light:#8b5cf6;--primary-dark:#5521d0;
  --accent:#00d4aa;--accent-light:#34ebc3;
  --bg:#0a0a1a;--bg-card:rgba(255,255,255,0.04);--bg-card-hover:rgba(255,255,255,0.08);
  --text:#e8e8f0;--text-muted:#8b8ba7;--text-dim:#5a5a7a;
  --border:rgba(255,255,255,0.08);--border-hover:rgba(255,255,255,0.15);
  --success:#22c55e;--error:#ef4444;--warning:#f59e0b;
  --radius:14px;--radius-sm:8px;--radius-lg:20px;
  --shadow:0 8px 32px rgba(0,0,0,0.4);
  --font:'Inter',system-ui,-apple-system,sans-serif;
  --glass:rgba(255,255,255,0.03);--glass-border:rgba(255,255,255,0.06);
}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:var(--font);background:var(--bg);color:var(--text);line-height:1.6;overflow-x:hidden;min-height:100vh}
a{color:var(--primary-light);text-decoration:none;transition:color .2s}
a:hover{color:var(--accent)}
img{max-width:100%;height:auto}
.hidden{display:none!important}
.gradient-text{background:linear-gradient(135deg,var(--primary-light),var(--accent));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}

#particles-bg{position:fixed;top:0;left:0;width:100%;height:100%;z-index:-1;pointer-events:none}
#particles-bg::before{content:'';position:absolute;top:10%;left:10%;width:500px;height:500px;border-radius:50%;background:radial-gradient(circle,rgba(108,61,255,0.12) 0%,transparent 70%);animation:pulse-bg 8s ease-in-out infinite}
#particles-bg::after{content:'';position:absolute;bottom:10%;right:10%;width:400px;height:400px;border-radius:50%;background:radial-gradient(circle,rgba(0,212,170,0.08) 0%,transparent 70%);animation:pulse-bg 10s ease-in-out infinite reverse}
@keyframes pulse-bg{0%,100%{transform:scale(1);opacity:.6}50%{transform:scale(1.2);opacity:1}}

.glass-card{background:var(--glass);border:1px solid var(--glass-border);border-radius:var(--radius);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);transition:all .3s ease}
.glass-card:hover{border-color:var(--border-hover);box-shadow:var(--shadow)}

.navbar{position:fixed;top:0;left:0;right:0;z-index:100;padding:12px 0;transition:all .3s;background:rgba(10,10,26,0.8);backdrop-filter:blur(20px);border-bottom:1px solid var(--border)}
.nav-container{max-width:1200px;margin:0 auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between}
.nav-logo{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.25rem;color:var(--text);text-decoration:none}
.logo-icon{font-size:1.5rem}
.nav-links{display:flex;gap:28px}
.nav-link{color:var(--text-muted);font-size:.9rem;font-weight:500;transition:color .2s;text-decoration:none}
.nav-link:hover{color:var(--text)}
.nav-actions{display:flex;align-items:center;gap:12px}
#nav-guest,.nav-user{display:flex;align-items:center;gap:10px}
.nav-lang-switch{display:flex;align-items:center;gap:4px;padding:3px;background:var(--bg-card);border:1px solid var(--border);border-radius:999px}
.lang-btn{min-width:34px;padding:5px 8px;border:0;border-radius:999px;background:transparent;color:var(--text-muted);font-family:var(--font);font-size:.72rem;font-weight:800;letter-spacing:.04em;cursor:pointer;transition:all .2s}
.lang-btn:hover{color:var(--text)}
.lang-btn.active{background:rgba(108,61,255,0.2);color:var(--text);box-shadow:0 0 0 1px rgba(108,61,255,0.2)}
.nav-credits{display:flex;align-items:center;gap:6px;padding:6px 14px;background:var(--bg-card);border-radius:20px;font-weight:600;font-size:.85rem}
.credits-icon{font-size:1rem}
.nav-avatar-wrap{position:relative;cursor:pointer}
.nav-avatar{width:36px;height:36px;border-radius:50%;background:linear-gradient(135deg,var(--primary),var(--accent));display:flex;align-items:center;justify-content:center;font-weight:700;font-size:.85rem;color:#fff}
.nav-dropdown{position:absolute;top:calc(100% + 8px);right:0;min-width:220px;background:rgba(20,20,40,0.98);border:1px solid var(--border);border-radius:var(--radius-sm);padding:8px 0;display:none;box-shadow:var(--shadow)}
.nav-dropdown.show{display:block}
.dropdown-header{padding:12px 16px}
#dropdown-name{display:block;font-weight:600;font-size:.9rem}
.dropdown-email{display:block;font-size:.75rem;color:var(--text-muted);margin-top:2px}
.dropdown-divider{height:1px;background:var(--border);margin:4px 0}
.dropdown-item{display:block;width:100%;text-align:left;padding:10px 16px;font-size:.85rem;color:var(--text);background:none;border:none;cursor:pointer;font-family:var(--font);transition:background .15s}
.dropdown-item:hover{background:var(--bg-card-hover)}
.dropdown-item.danger{color:var(--error)}
.nav-hamburger{display:none;flex-direction:column;gap:5px;background:none;border:none;cursor:pointer;padding:6px}
.nav-hamburger span{display:block;width:22px;height:2px;background:var(--text);border-radius:2px;transition:all .3s}

.btn-primary{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 28px;background:linear-gradient(135deg,var(--primary),var(--primary-dark));color:#fff;border:none;border-radius:var(--radius-sm);font-weight:600;font-size:.9rem;cursor:pointer;transition:all .25s;font-family:var(--font);text-decoration:none}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 6px 24px rgba(108,61,255,0.4);color:#fff}
.btn-outline{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 28px;background:transparent;color:var(--text);border:1px solid var(--border);border-radius:var(--radius-sm);font-weight:600;font-size:.9rem;cursor:pointer;transition:all .25s;font-family:var(--font);text-decoration:none}
.btn-outline:hover{border-color:var(--primary-light);color:var(--primary-light);background:rgba(108,61,255,0.05)}
.btn-ghost{background:none;border:none;color:var(--text-muted);font-weight:500;font-size:.9rem;cursor:pointer;padding:8px 16px;transition:color .2s;font-family:var(--font)}
.btn-ghost:hover{color:var(--text)}
.btn-sm{padding:8px 18px;font-size:.8rem}
.btn-lg{padding:14px 36px;font-size:1rem}
.btn-block{width:100%}
.btn-loader{display:inline-block;width:16px;height:16px;border:2px solid rgba(255,255,255,0.3);border-top-color:#fff;border-radius:50%;animation:spin .6s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}

.hero{min-height:100vh;display:flex;align-items:center;padding:120px 24px 80px;max-width:1200px;margin:0 auto;gap:60px}
.hero-content{flex:1;max-width:600px}
.hero-badge{display:inline-block;padding:6px 16px;background:rgba(108,61,255,0.15);color:var(--primary-light);border-radius:20px;font-size:.8rem;font-weight:600;margin-bottom:24px;border:1px solid rgba(108,61,255,0.2)}
.hero-title{font-size:clamp(2.2rem,5vw,3.8rem);font-weight:800;line-height:1.1;margin-bottom:20px}
.hero-subtitle{font-size:1.1rem;color:var(--text-muted);line-height:1.7;margin-bottom:36px;max-width:500px}
.hero-buttons{display:flex;gap:16px;flex-wrap:wrap;margin-bottom:48px}
.btn-arrow{transition:transform .25s}
.btn-primary:hover .btn-arrow{transform:translateX(4px)}
.hero-stats{display:flex;gap:40px}
.stat-item{text-align:center}
.stat-number{display:block;font-size:1.8rem;font-weight:800;color:var(--text)}
.stat-label{font-size:.75rem;color:var(--text-muted);text-transform:uppercase;letter-spacing:1px}
.hero-visual{flex:1;display:flex;justify-content:center;align-items:center;position:relative;min-height:360px}
.hero-preview-image{position:absolute;z-index:0;width:min(100%,430px);border-radius:var(--radius);border:1px solid var(--border);opacity:.18;transform:translate(24px,24px);box-shadow:var(--shadow)}
.hero-card{padding:32px;max-width:380px;width:100%;border:1px solid rgba(108,61,255,0.15);position:relative;z-index:1}
.mock-badge{display:inline-block;padding:4px 12px;background:rgba(108,61,255,0.2);border-radius:12px;font-size:.75rem;font-weight:600;color:var(--primary-light);margin-bottom:16px}
.mock-text{font-size:1rem;font-weight:600;margin-bottom:20px}
.mock-options{display:flex;flex-direction:column;gap:10px}
.mock-option{padding:12px 16px;background:rgba(255,255,255,0.03);border:1px solid var(--border);border-radius:var(--radius-sm);font-size:.85rem;transition:all .3s}
.mock-option.correct{border-color:var(--success);background:rgba(34,197,94,0.1);color:var(--success);font-weight:600}
.check{float:right;font-weight:700}
.mock-status{margin-top:16px;display:flex;align-items:center;gap:8px;font-size:.8rem;color:var(--accent)}
.status-dot{width:8px;height:8px;border-radius:50%;background:var(--accent);animation:pulse .8s ease-in-out infinite alternate}
@keyframes pulse{0%{opacity:.4}100%{opacity:1}}

.section-container{max-width:1200px;margin:0 auto;padding:0 24px}
.features,.platforms,.pricing,.mobile-section,.leaderboard-section,.dashboard-section{padding:100px 0}
.section-header{text-align:center;margin-bottom:60px}
.section-badge{display:inline-block;padding:6px 16px;background:rgba(108,61,255,0.12);color:var(--primary-light);border-radius:20px;font-size:.8rem;font-weight:600;margin-bottom:12px}
.section-title{font-size:clamp(1.8rem,3vw,2.5rem);font-weight:800;margin-bottom:12px}
.section-subtitle{color:var(--text-muted);font-size:1rem;max-width:500px;margin:0 auto}
.features-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:20px}
.feature-card{padding:28px;text-align:center}
.feature-icon{font-size:2rem;margin-bottom:14px}
.feature-card h3{font-size:1rem;font-weight:700;margin-bottom:8px}
.feature-card p{font-size:.85rem;color:var(--text-muted);line-height:1.6}
.platforms-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:14px}
.platform-card{padding:20px;text-align:center;font-size:.85rem;font-weight:600;display:flex;align-items:center;justify-content:center;gap:8px}
.platform-card span{font-size:1.2rem}

.pricing-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:24px;max-width:960px;margin:0 auto}
.pricing-card{padding:36px;position:relative;overflow:hidden}
.pricing-card.featured{border-color:var(--primary);box-shadow:0 0 40px rgba(108,61,255,0.15)}
.pricing-badge{position:absolute;top:16px;right:-32px;padding:4px 40px;background:var(--primary);color:#fff;font-size:.7rem;font-weight:700;transform:rotate(45deg);text-transform:uppercase}
.pricing-badge.best{background:var(--accent);color:var(--bg)}
.pricing-header{text-align:center;margin-bottom:28px}
.pricing-header h3{font-size:1.2rem;font-weight:700;margin-bottom:12px}
.pricing-amount{font-size:2.8rem;font-weight:800;margin-bottom:4px}
.price-dollar{font-size:1.2rem;vertical-align:super;color:var(--text-muted)}
.pricing-credits{color:var(--text-muted);font-size:.9rem}
.pricing-features{list-style:none;margin-bottom:28px;text-align:left}
.pricing-features li{padding:8px 0;font-size:.85rem;color:var(--text-muted);border-bottom:1px solid var(--border)}
.pricing-features li::before{content:'✓ ';color:var(--success);font-weight:700}

.tutorial-steps{padding:36px;max-width:700px;margin:0 auto}
.tutorial-step{display:flex;gap:20px;margin-bottom:28px;align-items:flex-start}
.tutorial-step:last-child{margin-bottom:0}
.step-number{width:40px;height:40px;flex-shrink:0;display:flex;align-items:center;justify-content:center;border-radius:50%;background:linear-gradient(135deg,var(--primary),var(--accent));color:#fff;font-weight:700;font-size:1rem}
.step-content h4{font-weight:700;margin-bottom:4px}
.step-content p{font-size:.85rem;color:var(--text-muted);line-height:1.6}
.step-content a{color:var(--primary-light)}

.leaderboard-table{max-width:600px;margin:0 auto;overflow:hidden}
.leaderboard-header{display:grid;grid-template-columns:50px 1fr 120px 100px;padding:14px 20px;font-weight:700;font-size:.8rem;color:var(--text-muted);text-transform:uppercase;letter-spacing:1px;border-bottom:1px solid var(--border)}
.leaderboard-row{display:grid;grid-template-columns:50px 1fr 120px 100px;padding:14px 20px;border-bottom:1px solid var(--border);font-size:.9rem;transition:background .2s}
.leaderboard-row:hover{background:var(--bg-card-hover)}
.leaderboard-row:last-child{border-bottom:none}
.leaderboard-rank{font-weight:800;color:var(--primary-light)}
.leaderboard-rank.gold{color:#ffd700}
.leaderboard-rank.silver{color:#c0c0c0}
.leaderboard-rank.bronze{color:#cd7f32}
.leaderboard-loading{padding:40px;text-align:center;color:var(--text-muted)}

.dashboard-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:20px;margin-bottom:32px}
.dash-card{padding:28px;text-align:center}
.dash-icon{font-size:2rem;margin-bottom:8px}
.dash-value{font-size:1.8rem;font-weight:800;margin-bottom:4px}
.dash-label{font-size:.8rem;color:var(--text-muted);margin-bottom:8px}
.dash-history{padding:28px}
.dash-history h3{margin-bottom:16px;font-size:1rem}
.dash-history-item{display:flex;justify-content:space-between;padding:10px 0;border-bottom:1px solid var(--border);font-size:.85rem}
.dash-empty{color:var(--text-muted);font-size:.85rem}

.footer{padding:60px 0 30px;border-top:1px solid var(--border);background:rgba(0,0,0,0.3)}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:40px;margin-bottom:40px}
.footer-brand .logo-icon,.footer-brand .logo-text{display:inline}
.footer-brand{font-size:1.1rem;font-weight:700}
.footer-desc{margin-top:12px;font-size:.85rem;color:var(--text-muted);line-height:1.6}
.footer-links h4{font-weight:700;margin-bottom:14px;font-size:.9rem}
.footer-links a{display:block;color:var(--text-muted);font-size:.85rem;margin-bottom:8px;transition:color .2s;text-decoration:none}
.footer-links a:hover{color:var(--text)}
.footer-bottom{text-align:center;padding-top:24px;border-top:1px solid var(--border);font-size:.8rem;color:var(--text-dim)}

.modal-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,0.7);backdrop-filter:blur(4px);z-index:200;display:flex;align-items:center;justify-content:center;padding:20px}
.modal{max-width:420px;width:100%;padding:40px;position:relative;animation:modal-in .3s ease}
@keyframes modal-in{from{opacity:0;transform:translateY(20px) scale(.95)}to{opacity:1;transform:translateY(0) scale(1)}}
.modal-close{position:absolute;top:16px;right:16px;background:none;border:none;color:var(--text-muted);font-size:1.5rem;cursor:pointer;line-height:1;padding:4px;transition:color .2s}
.modal-close:hover{color:var(--text)}
.modal-title{font-size:1.5rem;font-weight:800;margin-bottom:8px}
.modal-subtitle{color:var(--text-muted);font-size:.9rem;margin-bottom:28px}
.form-group{margin-bottom:14px}
.form-input{width:100%;padding:12px 16px;background:rgba(255,255,255,0.05);border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:.9rem;font-family:var(--font);transition:border-color .2s;outline:none}
.form-input:focus{border-color:var(--primary-light)}
.form-input::placeholder{color:var(--text-dim)}
.form-row{display:flex;align-items:center;justify-content:space-between;margin-bottom:20px}
.checkbox-label{display:flex;align-items:center;gap:8px;font-size:.85rem;color:var(--text-muted);cursor:pointer}
.checkbox-label input{accent-color:var(--primary)}
.form-error{padding:10px 14px;background:rgba(239,68,68,0.1);border:1px solid rgba(239,68,68,0.2);border-radius:var(--radius-sm);color:var(--error);font-size:.85rem;margin-bottom:14px}
.form-switch{text-align:center;margin-top:20px;font-size:.85rem;color:var(--text-muted)}
.form-switch a{color:var(--primary-light);font-weight:600}

.toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);padding:12px 28px;background:rgba(20,20,40,0.95);border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:.85rem;z-index:300;animation:toast-in .3s ease;box-shadow:var(--shadow)}
@keyframes toast-in{from{opacity:0;transform:translateX(-50%) translateY(10px)}to{opacity:1;transform:translateX(-50%) translateY(0)}}

.quiz-page{max-width:1180px;margin:0 auto;padding:128px 24px 90px}
.quiz-hero{margin-bottom:32px}
.quiz-hero h1{font-size:clamp(2rem,4vw,3.1rem);line-height:1.1;margin:14px 0 14px}
.quiz-hero p{max-width:760px;color:var(--text-muted)}
.quiz-auth-card{padding:32px;max-width:760px}
.quiz-auth-card h2{font-size:1.35rem;margin-bottom:8px}
.quiz-auth-card p{color:var(--text-muted);margin-bottom:20px}
.quiz-auth-grid{display:grid;grid-template-columns:1fr 1fr auto;gap:12px;align-items:center}
.quiz-shell,.practice-shell{display:grid;gap:20px}
.quiz-toolbar{display:flex;justify-content:space-between;gap:20px;align-items:center;padding:24px}
.quiz-toolbar h2{font-size:1.25rem;margin-bottom:2px}
.quiz-toolbar p{color:var(--text-muted);font-size:.9rem}
.quiz-toolbar-actions{display:flex;gap:10px;align-items:center;flex-wrap:wrap;justify-content:flex-end}
.quiz-toolbar-actions .form-input{width:auto;min-width:180px}
.quiz-empty{padding:36px;text-align:center}
.quiz-empty p{color:var(--text-muted);margin-top:8px}
.notes-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:16px}
.note-card{padding:20px;display:flex;flex-direction:column;gap:12px;border-color:var(--border)}
.note-card.is-selected{border-color:rgba(0,212,170,.5);box-shadow:0 0 0 1px rgba(0,212,170,.16)}
.note-card-top{display:flex;align-items:center;justify-content:space-between;gap:10px}
.note-check{display:flex;align-items:center;gap:8px;color:var(--text-muted);font-size:.8rem;cursor:pointer}
.note-check input{accent-color:var(--accent)}
.note-favorite{border:1px solid var(--border);background:var(--bg-card);color:var(--text-dim);border-radius:999px;width:32px;height:32px;cursor:pointer;transition:all .2s}
.note-favorite.active,.note-favorite:hover{color:#ffd700;border-color:rgba(255,215,0,.45);background:rgba(255,215,0,.08)}
.note-card h3{font-size:1rem;line-height:1.45}
.note-meta{display:flex;gap:8px;flex-wrap:wrap}
.note-meta span{font-size:.72rem;color:var(--text-muted);padding:3px 8px;border:1px solid var(--border);border-radius:999px;background:var(--bg-card)}
.note-answer,.note-explanation{font-size:.85rem;color:var(--text-muted);line-height:1.55}
.note-answer strong,.note-explanation strong{color:var(--text)}
.note-status{width:100%;padding:9px 12px;border-radius:var(--radius-sm);border:1px solid var(--border);background:rgba(255,255,255,.05);color:var(--text);font-family:var(--font)}
.practice-shell{padding:28px}
.practice-header{display:flex;justify-content:space-between;gap:16px;align-items:center}
.practice-progress{font-size:.9rem;color:var(--text-muted);font-weight:700}
.practice-card{display:grid;gap:18px}
.practice-meta{color:var(--accent);font-size:.82rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em}
.practice-card h2{font-size:1.5rem;line-height:1.35}
.practice-options{display:grid;gap:10px}
.practice-option{display:flex;align-items:flex-start;gap:10px;padding:14px 16px;border:1px solid var(--border);border-radius:var(--radius-sm);background:rgba(255,255,255,.035);cursor:pointer}
.practice-option:hover{border-color:var(--primary-light)}
.practice-option input{margin-top:3px;accent-color:var(--primary)}
.practice-feedback{padding:16px;border-radius:var(--radius-sm);font-size:.9rem;line-height:1.65}
.practice-feedback.success{background:rgba(34,197,94,.1);border:1px solid rgba(34,197,94,.25);color:#86efac}
.practice-feedback.error{background:rgba(239,68,68,.1);border:1px solid rgba(239,68,68,.25);color:#fca5a5}
.practice-actions{display:flex;gap:10px;flex-wrap:wrap}
.practice-result{text-align:center;padding:44px 0}
.practice-result h2{font-size:2rem;margin-bottom:8px}
.practice-result p{color:var(--text-muted);margin-bottom:24px}

@media(max-width:768px){
  .nav-links{display:none}
  .nav-hamburger{display:flex}
  .nav-lang-switch{order:-1}
  .nav-actions{gap:8px}
  .nav-links.show{display:flex;position:absolute;top:100%;left:0;right:0;flex-direction:column;padding:16px 24px;background:rgba(10,10,26,0.98);border-bottom:1px solid var(--border);gap:12px}
  .hero{flex-direction:column;padding-top:100px;gap:40px;min-height:auto}
  .hero-visual{order:-1}
  .hero-stats{gap:20px}
  .footer-grid{grid-template-columns:1fr 1fr}
  .leaderboard-header,.leaderboard-row{grid-template-columns:40px 1fr 80px 70px;padding:10px 14px;font-size:.8rem}
  .pricing-grid{grid-template-columns:1fr}
  .quiz-toolbar{align-items:stretch;flex-direction:column}
  .quiz-toolbar-actions{justify-content:flex-start}
  .quiz-toolbar-actions .form-input{width:100%}
  .quiz-auth-grid{grid-template-columns:1fr}
}
@media(max-width:480px){
  .hero-buttons{flex-direction:column}
  .hero-stats{flex-direction:column;gap:12px;align-items:center}
  .footer-grid{grid-template-columns:1fr}
  .dashboard-grid{grid-template-columns:1fr 1fr}
}