:root{--bg-color:#0f1115;--bg-color-alt:#16181d;--bg-card:#1c1f26;--text-main:#e2e8f0;--text-muted:#94a3b8;--accent-color:#f97316;--accent-hover:#ea580c;--accent-light:#f973161a;--border-color:#2dd4bf20;--border-card:#ffffff0d;--font-family:"Inter", system-ui, -apple-system, sans-serif;--line-height:1.6;--container-width:1100px;--spacing-sm:.5rem;--spacing-md:1rem;--spacing-lg:2rem;--spacing-xl:4rem;--transition:.3s cubic-bezier(.4, 0, .2, 1);--radius-sm:6px;--radius-md:12px;--radius-lg:20px}@media (prefers-color-scheme:light){:root{--bg-color:#fdfdfd;--bg-color-alt:#f1f5f9;--bg-card:#fff;--text-main:#0f172a;--text-muted:#475569;--border-color:#e2e8f0;--border-card:#e2e8f0}}*,:before,:after{box-sizing:border-box;margin:0;padding:0}body{font-family:var(--font-family);background-color:var(--bg-color);color:var(--text-main);line-height:var(--line-height);-webkit-font-smoothing:antialiased;transition:background-color var(--transition), color 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svg{color:var(--accent-color)}.main-nav{justify-self:center;align-items:center;display:flex}.nav-links{gap:var(--spacing-lg);font-size:.95rem;font-weight:500;display:flex}.auth-buttons{gap:var(--spacing-sm);justify-self:end;display:flex}@media (width<=768px){.nav-links,.auth-buttons .btn-ghost{display:none}}.hero{padding:calc(var(--spacing-xl) * 2) 0 var(--spacing-xl);text-align:center;background:radial-gradient(circle at top center, var(--accent-light) 0%, transparent 50%)}.hero h1{letter-spacing:-.03em;margin-bottom:var(--spacing-md);font-size:clamp(2.5rem,5vw,4.5rem);font-weight:800;line-height:1.1}.hero-subtitle{color:var(--text-muted);max-width:600px;margin:0 auto var(--spacing-lg);font-size:clamp(1.1rem,2vw,1.25rem)}.hero-actions{gap:var(--spacing-md);margin-bottom:var(--spacing-md);flex-wrap:wrap;justify-content:center;display:flex}.invite-note{color:var(--text-muted);font-size:.9rem;font-style:italic}.demo-section{padding:var(--spacing-xl) 0;background-color:var(--bg-color-alt);border-top:1px solid var(--border-card);border-bottom:1px solid var(--border-card)}.demo-container{gap:var(--spacing-xl);grid-template-columns:1fr 1fr;align-items:center;display:grid}@media (width<=860px){.demo-container{text-align:center;grid-template-columns:1fr}}.demo-intro h2{margin-bottom:var(--spacing-sm);font-size:2rem;font-weight:700}.demo-intro p{color:var(--text-muted);font-size:1.1rem}.demo-card-container{align-items:center;gap:var(--spacing-md);perspective:1000px;flex-direction:column;display:flex}.flashcard{cursor:pointer;width:100%;max-width:400px;height:280px}.flashcard-inner{text-align:center;width:100%;height:100%;transform-style:preserve-3d;transition:transform .6s cubic-bezier(.4,0,.2,1);position:relative}.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{backface-visibility:hidden;width:100%;height:100%;padding:var(--spacing-lg);border-radius:var(--radius-lg);background-color:var(--bg-card);border:1px solid var(--border-card);flex-direction:column;justify-content:center;align-items:center;display:flex;position:absolute;box-shadow:0 10px 30px #0000001a}@media (prefers-color-scheme:light){.flashcard-front,.flashcard-back{box-shadow:0 10px 30px #0000000d}}.flashcard-front{z-index:2}.flashcard-back{background:linear-gradient(135deg, var(--bg-card), #f973160d);border-color:var(--accent-color);transform:rotateY(180deg)}.word-type{text-transform:uppercase;letter-spacing:.1em;color:var(--accent-color);margin-bottom:.5rem;font-size:.85rem;font-weight:700}.word{letter-spacing:-.02em;margin-bottom:.5rem;font-size:2.5rem;font-weight:800}.pronunciation{color:var(--text-muted);margin-bottom:1.5rem;font-family:monospace;font-size:1rem}.hint{color:var(--text-muted);opacity:.7;font-size:.85rem;transition:opacity .3s}.flashcard:hover .hint{opacity:1}.definition{margin-bottom:1rem;font-size:1.1rem;font-weight:500}.example-sentence{color:var(--text-muted);border-top:1px dashed var(--border-card);padding-top:1rem;font-size:.95rem;font-style:italic}.example-sentence strong{color:var(--accent-color)}.section-header{text-align:center;max-width:600px;margin:0 auto var(--spacing-xl)}.section-header h2{margin-bottom:var(--spacing-sm);letter-spacing:-.02em;font-size:2.25rem;font-weight:800}.section-header p{color:var(--text-muted);font-size:1.1rem}.features{padding:var(--spacing-xl) 0}.features-grid{gap:var(--spacing-lg);grid-template-columns:repeat(auto-fit,minmax(300px,1fr));display:grid}.feature-card{padding:var(--spacing-lg);background-color:var(--bg-card);border-radius:var(--radius-md);border:1px solid var(--border-card);transition:border-color var(--transition)}.feature-card:hover{border-color:var(--accent-light)}.feature-icon{margin-bottom:var(--spacing-md);font-size:2.5rem}.feature-card h3{margin-bottom:var(--spacing-sm);font-size:1.25rem;font-weight:700}.feature-card p{color:var(--text-muted);font-size:.95rem}.pricing{padding:var(--spacing-xl) 0 calc(var(--spacing-xl) * 2);background-color:var(--bg-color-alt)}.pricing-grid{gap:var(--spacing-lg);grid-template-columns:repeat(auto-fit,minmax(300px,1fr));max-width:800px;margin:0 auto;display:grid}.pricing-card{background-color:var(--bg-card);border-radius:var(--radius-lg);border:1px solid var(--border-card);padding:var(--spacing-lg);flex-direction:column;display:flex;position:relative}.pricing-card h3{margin-bottom:var(--spacing-sm);font-size:1.5rem;font-weight:700}.price{color:var(--text-muted);margin-bottom:var(--spacing-lg);border-bottom:1px solid var(--border-card);padding-bottom:var(--spacing-lg);font-size:1rem;font-weight:500}.price span{color:var(--text-main);letter-spacing:-.04em;font-size:3rem;font-weight:800}.pricing-features{margin-bottom:var(--spacing-lg);flex-grow:1}.pricing-features li{color:var(--text-muted);align-items:center;gap:.75rem;margin-bottom:.75rem;font-size:.95rem;display:flex}.pricing-features li svg{color:var(--accent-color);flex-shrink:0}.pricing-card.featured{border:2px solid var(--accent-color)}.pricing-card.featured .badge{background-color:var(--accent-color);color:#fff;text-transform:uppercase;letter-spacing:.05em;border-radius:100px;padding:.25rem .75rem;font-size:.75rem;font-weight:700;position:absolute;top:-12px;left:50%;transform:translate(-50%)}.pricing-note{text-align:center;margin-top:var(--spacing-xl);color:var(--text-muted);font-size:.95rem}@media (width<=768px){.pricing-card.featured{border:2px solid var(--accent-color)}}.modal-overlay{-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px);z-index:1000;opacity:0;visibility:hidden;width:100vw;height:100vh;transition:opacity var(--transition), visibility var(--transition);background-color:#000000b3;justify-content:center;align-items:center;display:flex;position:fixed;top:0;left:0}.modal-overlay.active{opacity:1;visibility:visible}.modal{background-color:var(--bg-card);border-radius:var(--radius-md);width:100%;max-width:400px;padding:var(--spacing-lg) var(--spacing-xl);opacity:0;border:1px solid var(--border-card);transition:transform .4s cubic-bezier(.4,0,.2,1),opacity .4s;display:none;position:relative;transform:translateY(20px);box-shadow:0 10px 40px #0003}.modal.active{opacity:1;display:block;transform:translateY(0)}.close-modal{color:var(--text-muted);cursor:pointer;transition:color var(--transition);background:0 0;border:none;font-size:1.5rem;position:absolute;top:1rem;right:1.5rem}.close-modal:hover{color:var(--text-main)}.modal h2{margin-bottom:var(--spacing-md);text-align:center;font-size:1.5rem;font-weight:700}.modal-desc{color:var(--text-muted);margin-bottom:var(--spacing-md);text-align:center;font-size:.95rem}.form-group{margin-bottom:var(--spacing-md)}.form-group label{color:var(--text-muted);margin-bottom:.5rem;font-size:.85rem;font-weight:600;display:block}.form-control{background-color:var(--bg-color);border:1px solid var(--border-card);border-radius:var(--radius-sm);width:100%;color:var(--text-main);transition:border-color var(--transition);padding:.75rem 1rem;font-family:inherit;font-size:.95rem}.form-control:focus{border-color:var(--accent-color);outline:none}.alert{border-radius:var(--radius-sm);margin-bottom:var(--spacing-md);padding:.75rem 1rem;font-size:.85rem;font-weight:500;line-height:1.4}.alert.error{color:#ef4444;background-color:#ef44441a;border:1px solid #ef444433}.alert.success{color:#10b981;background-color:#10b9811a;border:1px solid #10b98133}.site-footer{color:#a1a1aa;padding:var(--spacing-xl) 0 var(--spacing-md);background-color:#000;border-top:1px solid #1f1f22}@media (prefers-color-scheme:light){.site-footer{color:#64748b;background-color:#f8fafc;border-top:1px solid #e2e8f0}}.footer-content{gap:var(--spacing-lg);margin-bottom:var(--spacing-xl);grid-template-columns:2fr 1fr 1fr 1fr;display:grid}@media (width<=860px){.footer-content{grid-template-columns:1fr 1fr}.footer-brand{grid-column:1/-1}}.footer-brand .logo{color:#fff;margin-bottom:var(--spacing-sm)}@media (prefers-color-scheme:light){.footer-brand .logo{color:#0f172a}}.footer-brand p{max-width:250px;font-size:.9rem}.footer-links h4{color:#fff;margin-bottom:var(--spacing-md);font-size:1rem;font-weight:600}@media (prefers-color-scheme:light){.footer-links h4{color:#0f172a}}.footer-links li{margin-bottom:.5rem}.footer-links a{font-size:.9rem}.footer-links a:hover{color:#fff}@media (prefers-color-scheme:light){.footer-links a:hover{color:var(--accent-color)}}.footer-bottom{text-align:center;padding-top:var(--spacing-md);border-top:1px solid #1f1f22;font-size:.85rem}@media (prefers-color-scheme:light){.footer-bottom{border-top:1px solid #e2e8f0}}