:root{--primary:#4f46e5;--primary-hover:#4338ca;--primary-light:#e0e7ff;--bg:#f8fafc;--white:#fff;--text:#1e293b;--text-secondary:#64748b;--border:#e2e8f0;--success:#10b981;--error:#ef4444;--warning:#f59e0b;--shadow:0 1px 3px rgba(0,0,0,.1),0 1px 2px rgba(0,0,0,.06);--shadow-lg:0 10px 15px -3px rgba(0,0,0,.1),0 4px 6px -2px rgba(0,0,0,.05);--radius:12px;--radius-sm:8px}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,sans-serif;background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh}a{color:var(--primary);text-decoration:none}a:hover{color:var(--primary-hover)}.header{background:var(--white);border-bottom:1px solid var(--border);padding:0 24px;position:-webkit-sticky;position:sticky;top:0;z-index:100;box-shadow:var(--shadow)}.header-inner{max-width:1200px;margin:0 auto;justify-content:space-between;height:64px}.header-inner,.logo{display:flex;align-items:center}.logo{font-size:20px;font-weight:700;color:var(--primary);gap:8px}.logo svg{width:28px;height:28px}.nav{display:flex;gap:4px}.nav a{padding:8px 16px;border-radius:var(--radius-sm);color:var(--text-secondary);font-weight:500;font-size:14px;transition:all .2s}.nav a.active,.nav a:hover{background:var(--primary-light);color:var(--primary)}.footer{background:var(--white);border-top:1px solid var(--border);padding:24px;margin-top:auto}.footer-inner{max-width:1200px;margin:0 auto;display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:16px}.footer-inner p{color:var(--text-secondary);font-size:14px}.footer-links{display:flex;gap:20px}.footer-links a{color:var(--text-secondary);font-size:14px;display:flex;align-items:center;gap:6px}.footer-links a:hover{color:var(--primary)}.main-container{max-width:1200px;margin:0 auto;padding:40px 24px;min-height:calc(100vh - 64px - 80px)}.page-title{font-size:28px;font-weight:700;margin-bottom:8px}.page-desc{color:var(--text-secondary);font-size:16px;margin-bottom:32px}.card{background:var(--white);border-radius:var(--radius);padding:32px;box-shadow:var(--shadow);border:1px solid var(--border)}.upload-area{border:2px dashed var(--border);border-radius:var(--radius);padding:48px 24px;text-align:center;cursor:pointer;transition:all .3s;background:var(--bg)}.upload-area.dragover,.upload-area:hover{border-color:var(--primary);background:var(--primary-light)}.upload-area svg{width:48px;height:48px;color:var(--text-secondary);margin-bottom:16px}.upload-area h3{font-size:18px;margin-bottom:8px}.upload-area p{color:var(--text-secondary);font-size:14px}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 24px;border-radius:var(--radius-sm);font-size:16px;font-weight:600;cursor:pointer;border:none;transition:all .2s}.btn-primary{background:var(--primary);color:var(--white)}.btn-primary:hover{background:var(--primary-hover)}.btn-primary:disabled{opacity:.5;cursor:not-allowed}.btn-secondary{background:var(--bg);color:var(--text);border:1px solid var(--border)}.btn-secondary:hover{background:var(--border)}.btn-success{background:var(--success);color:var(--white)}.btn-success:hover{background:#059669}.file-info{display:flex;align-items:center;gap:12px;padding:16px;background:var(--bg);border-radius:var(--radius-sm);margin-top:16px}.file-info svg{width:24px;height:24px;color:var(--primary)}.file-info .file-name{font-weight:600;font-size:14px}.file-info .file-size{color:var(--text-secondary);font-size:13px}.file-info .file-remove{margin-left:auto;background:none;border:none;color:var(--text-secondary);cursor:pointer;padding:4px}.file-info .file-remove:hover{color:var(--error)}.progress-bar{width:100%;height:8px;background:var(--border);border-radius:4px;overflow:hidden;margin:16px 0}.progress-bar .progress-fill{height:100%;background:var(--primary);border-radius:4px;transition:width .3s}.result-area{margin-top:24px;padding:20px;background:#f0fdf4;border:1px solid #bbf7d0;border-radius:var(--radius-sm);display:flex;align-items:center;gap:12px}.result-area.error{background:#fef2f2;border-color:#fecaca}.result-area svg{width:24px;height:24px;flex-shrink:0}.result-area.success svg{color:var(--success)}.result-area.error svg{color:var(--error)}.features-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));grid-gap:24px;gap:24px;margin-top:32px}.feature-card{background:var(--white);border-radius:var(--radius);padding:32px;box-shadow:var(--shadow);border:1px solid var(--border);text-align:center;transition:all .3s;cursor:pointer;text-decoration:none;color:var(--text);display:block}.feature-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--primary)}.feature-card .icon{width:64px;height:64px;border-radius:16px;background:var(--primary-light);display:flex;align-items:center;justify-content:center;margin:0 auto 16px}.feature-card .icon svg{width:32px;height:32px;color:var(--primary)}.feature-card h3{font-size:20px;margin-bottom:8px}.feature-card p{color:var(--text-secondary);font-size:14px}.history-table{width:100%;border-collapse:collapse;margin-top:16px}.history-table td,.history-table th{text-align:left;padding:12px 16px;border-bottom:1px solid var(--border)}.history-table th{font-weight:600;font-size:13px;color:var(--text-secondary);text-transform:uppercase;letter-spacing:.05em}.history-table td{font-size:14px}.history-table tr:hover td{background:var(--bg)}.badge{display:inline-block;padding:4px 10px;border-radius:9999px;font-size:12px;font-weight:600}.badge-success{background:#dcfce7;color:#166534}.badge-error{background:#fef2f2;color:#991b1b}@media (max-width:768px){.header-inner{flex-direction:column;height:auto;padding:12px 0;gap:8px}.nav{flex-wrap:wrap;justify-content:center}.main-container{padding:24px 16px}.page-title{font-size:22px}.features-grid{grid-template-columns:1fr}.footer-inner{flex-direction:column;text-align:center}}.spinner{display:inline-block;width:20px;height:20px;border:2px solid var(--white);border-top:2px solid transparent;border-radius:50%;animation:spin .6s linear infinite}@keyframes spin{to{transform:rotate(1turn)}}.convert-actions{display:flex;gap:12px;margin-top:24px;align-items:center}