*{margin:0;padding:0;box-sizing:border-box;}:root{--primary-color:#6366f1;--primary-dark:#4f46e5;--secondary-color:#8b5cf6;--accent-color:#ec4899;--bg-color:#f8fafc;--card-bg:#ffffff;--text-color:#1e293b;--text-light:#64748b;--border-color:#e2e8f0;--success-color:#10b981;--youtube-red:#ff0000;--shadow:0 4px 6px -1px rgba(0,0,0,0.1),0 2px 4px -1px rgba(0,0,0,0.06);--shadow-lg:0 10px 15px -3px rgba(0,0,0,0.1),0 4px 6px -2px rgba(0,0,0,0.05);}body{font-family:'Segoe UI',Tahoma,Geneva,Verdana,sans-serif;background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);color:var(--text-color);line-height:1.6;min-height:100vh;padding:2rem 1rem;}.back-btn{display:inline-flex;align-items:center;gap:0.5rem;padding:0.75rem 1.5rem;background:var(--card-bg);color:var(--primary-color);text-decoration:none;border-radius:12px;font-weight:600;font-size:1rem;box-shadow:var(--shadow);transition:all 0.3s ease;margin-bottom:2rem;position:relative;overflow:hidden;border:2px solid transparent;}.back-btn::before{content:'';position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(99,102,241,0.1),transparent);transition:left 0.5s ease;}.back-btn:hover::before{left:100%;}.back-btn:hover{background:var(--primary-color);color:white;transform:translateX(-5px);box-shadow:var(--shadow-lg);border-color:var(--primary-color);}.back-btn:active{transform:translateX(-3px)scale(0.98);}.container{max-width:800px;margin:0 auto;background:var(--card-bg);padding:2.5rem 2rem;border-radius:16px;box-shadow:var(--shadow-lg);animation:fadeInUp 0.6s ease;}.container h1{font-size:2rem;color:var(--primary-color);margin-bottom:1rem;text-align:center;}.container > p{font-size:1rem;color:var(--text-light);text-align:center;margin-bottom:2rem;line-height:1.7;}.input-box{display:flex;flex-direction:column;gap:1rem;margin-bottom:2rem;}#ytLink{width:100%;padding:1rem 1.25rem;font-size:1rem;border:2px solid var(--border-color);border-radius:12px;transition:all 0.3s ease;background:var(--bg-color);}#ytLink:focus{outline:none;border-color:var(--youtube-red);box-shadow:0 0 0 4px rgba(255,0,0,0.1);background:white;}#ytLink::placeholder{color:var(--text-light);}#fetchBtn{padding:1.25rem 2rem;background:linear-gradient(135deg,var(--primary-color)0%,var(--secondary-color)100%);color:white;border:none;border-radius:12px;font-size:1.05rem;font-weight:600;cursor:pointer;transition:all 0.3s ease;box-shadow:var(--shadow);position:relative;overflow:hidden;}#fetchBtn::before{content:'';position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(255,255,255,0.2),transparent);transition:left 0.5s ease;}#fetchBtn:hover::before{left:100%;}#fetchBtn:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);background:linear-gradient(135deg,var(--primary-dark)0%,var(--secondary-color)100%);}#fetchBtn:active{transform:translateY(-1px);}#fetchBtn:disabled{background:var(--text-light);cursor:not-allowed;box-shadow:none;}.thumbnail-preview{background:var(--bg-color);border:2px dashed var(--border-color);border-radius:12px;padding:2rem;min-height:200px;display:flex;align-items:center;justify-content:center;margin-bottom:2rem;position:relative;overflow:hidden;transition:all 0.3s ease;}.thumbnail-preview:empty::after{content:'🖼️ Thumbnail will appear here';color:var(--text-light);font-size:1.1rem;font-weight:500;}.thumbnail-preview img{max-width:100%;height:auto;border-radius:8px;box-shadow:var(--shadow-lg);transition:all 0.3s ease;animation:fadeIn 0.5s ease;}.thumbnail-preview:has(img){border-style:solid;border-color:var(--primary-color);padding:1rem;background:white;}.thumbnail-preview img:hover{transform:scale(1.02);box-shadow:0 15px 30px rgba(0,0,0,0.2);}.download-btn{display:inline-flex;align-items:center;justify-content:center;gap:0.5rem;padding:1.25rem 2.5rem;background:linear-gradient(135deg,var(--success-color)0%,#059669 100%);color:white;text-decoration:none;border-radius:12px;font-size:1.1rem;font-weight:600;box-shadow:var(--shadow);transition:all 0.3s ease;position:relative;overflow:hidden;width:100%;max-width:400px;margin:0 auto;}.download-btn::before{content:'';position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(255,255,255,0.3),transparent);transition:left 0.5s ease;}.download-btn:hover::before{left:100%;}.download-btn:hover{transform:translateY(-3px)scale(1.02);box-shadow:var(--shadow-lg);background:linear-gradient(135deg,#059669 0%,#047857 100%);}.download-btn:active{transform:translateY(-1px)scale(1);}.download-btn.hidden{display:none;}.how-to-section{background:var(--bg-color);border-radius:12px;padding:2rem;margin:3rem 0 2rem;border:2px solid var(--border-color);}.how-to-section h2{font-size:1.8rem;color:var(--primary-color);margin-bottom:2rem;text-align:center;font-weight:700;}.steps-container{display:grid;gap:1.5rem;margin-bottom:2rem;}.step-item{display:flex;gap:1.5rem;background:white;padding:1.5rem;border-radius:12px;border:2px solid var(--border-color);transition:all 0.3s ease;align-items:flex-start;}.step-item:hover{border-color:var(--primary-color);box-shadow:var(--shadow);transform:translateY(-2px);}.step-number{flex-shrink:0;width:50px;height:50px;background:linear-gradient(135deg,var(--primary-color)0%,var(--secondary-color)100%);color:white;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:1.5rem;font-weight:700;box-shadow:var(--shadow);}.step-content h3{font-size:1.2rem;color:var(--text-color);margin-bottom:0.5rem;font-weight:600;}.step-content p{font-size:1rem;color:var(--text-color);line-height:1.7;margin:0;}.tips-box{background:linear-gradient(135deg,rgba(255,193,7,0.1)0%,rgba(255,152,0,0.1)100%);border:2px solid #ffc107;border-left:4px solid #ffc107;border-radius:12px;padding:1.5rem;margin-top:2rem;}.tips-box h3{font-size:1.3rem;color:var(--text-color);margin-bottom:1rem;font-weight:600;}.tips-box ul{list-style:none;padding:0;margin:0;}.tips-box ul li{padding:0.75rem 0;padding-left:1.5rem;position:relative;color:var(--text-color);line-height:1.7;}.tips-box ul li::before{content:'✓';position:absolute;left:0;color:var(--success-color);font-weight:700;font-size:1.2rem;}.tips-box ul li strong{color:var(--primary-color);font-weight:700;}.faq-section{background:var(--bg-color);border-radius:12px;padding:2rem;margin:2rem 0;border:2px solid var(--border-color);}.faq-section h2{font-size:1.8rem;color:var(--primary-color);margin-bottom:2rem;text-align:center;font-weight:700;}.faq-item{background:white;border:2px solid var(--border-color);border-left:4px solid var(--primary-color);border-radius:12px;padding:1.5rem;margin-bottom:1.5rem;transition:all 0.3s ease;}.faq-item:hover{box-shadow:var(--shadow);transform:translateY(-2px);}.faq-item h3{font-size:1.1rem;color:var(--primary-color);margin-bottom:0.75rem;font-weight:600;line-height:1.5;}.faq-item p{font-size:1rem;color:var(--text-color);line-height:1.7;margin:0;}.blog-cta{background:linear-gradient(135deg,rgba(99,102,241,0.1)0%,rgba(139,92,246,0.1)100%);border:2px solid var(--primary-color);border-radius:12px;padding:2.5rem;text-align:center;margin-top:2rem;}.blog-cta-content h3{font-size:1.8rem;color:var(--text-color);margin-bottom:1rem;font-weight:700;}.blog-cta-content p{font-size:1.1rem;color:var(--text-light);margin-bottom:1.5rem;line-height:1.8;}.blog-btn{display:inline-block;padding:1rem 2.5rem;background:linear-gradient(135deg,var(--primary-color)0%,var(--secondary-color)100%);color:white;text-decoration:none;border-radius:10px;font-weight:700;font-size:1.05rem;box-shadow:var(--shadow);transition:all 0.3s ease;}.blog-btn:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);}.ad-sidebar{width:100%;max-width:300px;margin:20px auto;text-align:center;border-radius:8px;}@media(min-width:640px){.container h1{font-size:2.25rem;}.input-box{flex-direction:row;gap:1rem;}#ytLink{flex:1;}#fetchBtn{white-space:nowrap;flex-shrink:0;}.download-btn{width:auto;}.step-item{flex-direction:row;}}@media(min-width:768px){body{padding:3rem 2rem;}.container{padding:3rem 2.5rem;}.container h1{font-size:2.5rem;}.container > p{font-size:1.1rem;}.thumbnail-preview{padding:3rem;min-height:300px;}.thumbnail-preview:empty::after{font-size:1.25rem;}.how-to-section,.faq-section{padding:2.5rem;}.how-to-section h2,.faq-section h2{font-size:2rem;}}@media(min-width:1024px){.container h1{font-size:3rem;}}@media(max-width:640px){.step-item{flex-direction:column;text-align:center;}.step-number{margin:0 auto;}.how-to-section,.faq-section{padding:1.5rem;}.tips-box{padding:1.25rem;}.faq-item{padding:1.25rem;}}@keyframes fadeInUp{from{opacity:0;transform:translateY(30px);}to{opacity:1;transform:translateY(0);}}@keyframes fadeIn{from{opacity:0;transform:scale(0.95);}to{opacity:1;transform:scale(1);}}*:focus{outline:2px solid var(--primary-color);outline-offset:2px;}@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:0.01ms !important;animation-iteration-count:1 !important;transition-duration:0.01ms !important;}}