:root{--primary-color:#4361ee;--secondary-color:#3a0ca3;--accent-color:#7209b7;--light-color:#f8f9fa;--dark-color:#212529;--gray-color:#6c757d;--success-color:#4cc9f0;--warning-color:#f72585;--convert-primary:#059669;--convert-gradient:linear-gradient(135deg,#10b981 0%,#047857 100%);--border-radius:12px;--box-shadow:0 8px 24px rgba(0,0,0,0.1);--transition:all 0.3s ease}*{margin:0;padding:0;box-sizing:border-box;font-family:'Segoe UI','Microsoft YaHei',sans-serif}body{background-color:#f0f2f5;color:var(--dark-color);line-height:1.6}.container{width:100%;max-width:1200px;margin:0 auto;padding:0 20px}header{background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));color:white;padding:20px 0;box-shadow:0 4px 12px rgba(0,0,0,0.1);position:sticky;top:0;z-index:100}.header-content{display:flex;justify-content:space-between;align-items:center}.logo{display:flex;align-items:center;gap:15px}.logo i{font-size:2.5rem}.logo h1{font-size:1.8rem;font-weight:700}.logo span{color:var(--success-color)}nav ul{display:flex;list-style:none;gap:25px}nav a{color:white;text-decoration:none;font-weight:600;font-size:1.1rem;padding:8px 12px;border-radius:6px;transition:var(--transition)}nav a:hover,nav a.active{background-color:rgba(255,255,255,0.2)}main{padding:40px 0}.section-title{font-size:1.8rem;margin-bottom:25px;color:var(--secondary-color);display:flex;align-items:center;gap:10px}.section-title i{color:var(--accent-color)}.tools-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:25px;margin-bottom:40px}.tool-card{background:white;border-radius:var(--border-radius);padding:25px;box-shadow:var(--box-shadow);transition:var(--transition);cursor:pointer;border:2px solid transparent}.tool-card:hover{transform:translateY(-5px);border-color:var(--primary-color)}.tool-card i{font-size:2.5rem;color:var(--primary-color);margin-bottom:15px}.tool-card h3{font-size:1.4rem;margin-bottom:10px;color:var(--dark-color)}.tool-card p{color:var(--gray-color);margin-bottom:20px}.use-tool-btn{background-color:var(--primary-color);color:white;border:none;padding:10px 20px;border-radius:6px;font-weight:600;cursor:pointer;transition:var(--transition);width:100%}.use-tool-btn:hover{background-color:var(--secondary-color)}.tool-detail{background:white;border-radius:var(--border-radius);padding:30px;box-shadow:var(--box-shadow);margin-top:30px;display:none}.tool-detail.active{display:block}.tool-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:25px;padding-bottom:15px;border-bottom:2px solid #f0f2f5}.tool-header h2{font-size:1.6rem;color:var(--secondary-color)}.close-tool{background:none;border:none;font-size:1.5rem;color:var(--gray-color);cursor:pointer;transition:var(--transition)}.close-tool:hover{color:var(--warning-color)}.converter-layout{display:flex;flex-wrap:wrap;gap:30px}.converter-settings{flex:1;min-width:300px;background:#f8fafc;border-radius:12px;padding:25px;border:1px solid #e2e8f0}.setting-group{margin-bottom:25px}.setting-label{display:block;font-weight:700;color:var(--secondary-color);margin-bottom:10px}.form-select,.form-input{width:100%;padding:12px;border:2px solid #e2e8f0;border-radius:8px;font-size:1rem;outline:none;transition:var(--transition)}.form-select:focus{border-color:var(--convert-primary)}.drop-zone{border:2px dashed #cbd5e1;border-radius:12px;padding:30px 20px;text-align:center;cursor:pointer;transition:var(--transition);background:white;position:relative}.drop-zone:hover,.drop-zone.dragover{border-color:var(--convert-primary);background:#ecfdf5}.drop-zone i{font-size:3rem;color:var(--gray-color);margin-bottom:15px}.drop-zone p{color:var(--gray-color);margin-bottom:10px}.drop-zone .file-info{font-size:0.9rem;color:var(--convert-primary);font-weight:600}.range-container{display:flex;align-items:center;gap:15px}input[type=range]{flex:1;-webkit-appearance:none;height:6px;background:#cbd5e1;border-radius:5px;outline:none}input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:20px;height:20px;border-radius:50%;background:var(--convert-primary);cursor:pointer}.convert-btn{width:100%;padding:15px;background:var(--convert-gradient);color:white;border:none;border-radius:8px;font-size:1.1rem;font-weight:700;cursor:pointer;transition:var(--transition);display:flex;align-items:center;justify-content:center;gap:10px;box-shadow:0 4px 12px rgba(5,150,105,0.3)}.convert-btn:hover{transform:translateY(-2px);box-shadow:0 6px 16px rgba(5,150,105,0.4)}.convert-btn:disabled{background:#9ca3af;cursor:not-allowed;transform:none;box-shadow:none}.converter-preview{flex:2;min-width:300px;display:flex;flex-direction:column;gap:15px}.preview-box{background:#f1f5f9;border:1px solid #e2e8f0;border-radius:12px;min-height:400px;display:flex;align-items:center;justify-content:center;overflow:hidden;position:relative}.preview-box img{max-width:100%;max-height:500px;object-fit:contain}.empty-state{color:var(--gray-color);text-align:center}.status-bar{display:flex;justify-content:space-between;background:#ecfdf5;border:1px solid #a7f3d0;color:#065f46;padding:10px 15px;border-radius:8px;font-size:0.9rem;display:none}@media (max-width:768px){.converter-layout{flex-direction:column}.drop-zone{padding:20px}}