:root{--bg:#f5f5f7;--card-bg:#fff;--text:#1a1a1a;--text-secondary:#666;--border:#e0e0e0;--primary:#2563eb;--primary-hover:#1d4ed8;--primary-disabled:#93b4f5;--accent-bg:#2563eb0f;--accent-border:#2563eb4d;--danger:#dc2626;--success:#16a34a;--shadow:0 1px 3px #00000014, 0 1px 2px #0000000f;--shadow-lg:0 4px 12px #0000001a;--radius:12px;--radius-sm:8px;--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light dark;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif}@media (prefers-color-scheme:dark){:root{--lightningcss-light: ;--lightningcss-dark:initial;--bg:#0f0f11;--card-bg:#1c1c1f;--text:#e5e5e5;--text-secondary:#999;--border:#2e2e32;--primary:#3b82f6;--primary-hover:#60a5fa;--primary-disabled:#1e3a6e;--accent-bg:#3b82f61a;--accent-border:#3b82f64d;--shadow:0 1px 3px #0000004d;--shadow-lg:0 4px 12px #0006}}*,:before,:after{box-sizing:border-box}body{background:var(--bg);color:var(--text);margin:0}.container{max-width:880px;margin:0 auto;padding:40px 24px 80px}.header{text-align:center;margin-bottom:40px}.header h1{letter-spacing:-.5px;margin:0 0 8px;font-size:32px;font-weight:700}.subtitle{color:var(--text-secondary);margin:0;font-size:16px}.grid{grid-template-columns:1fr 1fr;gap:24px;display:grid}@media (width<=640px){.grid{grid-template-columns:1fr}}.card{background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:24px}.card h2{margin:0 0 16px;font-size:18px;font-weight:600}.dropzone{border:2px dashed var(--border);border-radius:var(--radius-sm);cursor:pointer;-webkit-user-select:none;user-select:none;padding:32px 16px;transition:border-color .2s,background .2s}.dropzone:hover,.dropzone--over{border-color:var(--primary);background:var(--accent-bg)}.dropzone--done{border-style:solid;border-color:var(--accent-border);background:var(--accent-bg)}.dropzone-content{text-align:center;flex-direction:column;align-items:center;gap:8px;display:flex}.drop-icon{font-size:32px;line-height:1}.drop-filename{word-break:break-all;font-size:14px;font-weight:500}.drop-hint{color:var(--text-secondary);font-size:13px}.preview{margin-top:20px}.preview h3{color:var(--text-secondary);text-transform:uppercase;letter-spacing:.5px;margin:0 0 12px;font-size:14px;font-weight:600}.preview img{border-radius:var(--radius-sm);max-width:100%;max-height:320px;box-shadow:var(--shadow-lg);object-fit:contain;margin:0 auto;display:block}.no-cover{text-align:center;color:var(--text-secondary);margin-top:20px;font-size:14px;font-style:italic}.separator{background:var(--border);border:none;height:1px;margin:32px 0}.output-section{background:var(--card-bg);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:24px}.field{margin-bottom:20px}.field-label{color:var(--text);margin-bottom:8px;font-size:14px;font-weight:600;display:block}.filename-row{align-items:center;gap:0;display:flex}.input{border:1px solid var(--border);border-radius:var(--radius-sm) 0 0 var(--radius-sm);background:var(--bg);color:var(--text);outline:none;flex:1;padding:10px 14px;font-size:16px;transition:border-color .2s}.input:focus{border-color:var(--primary)}.epub-ext{background:var(--accent-bg);border:1px solid var(--border);border-radius:0 var(--radius-sm) var(--radius-sm) 0;color:var(--text-secondary);white-space:nowrap;border-left:none;padding:10px 14px;font-size:16px;font-weight:500}.progress{margin-bottom:16px}.progress-track{background:var(--border);border-radius:2px;height:4px;overflow:hidden}.progress-indicator{background:var(--primary);border-radius:2px;height:100%;animation:1.5s ease-in-out infinite indeterminate}@keyframes indeterminate{0%{width:40%;transform:translate(-100%)}50%{width:60%;transform:translate(60%)}to{width:40%;transform:translate(200%)}}.error-msg{color:var(--danger);margin:0 0 16px;font-size:14px}.success-msg{color:var(--success);margin:0 0 16px;font-size:14px;font-weight:500}.hint-text{text-align:center;color:var(--text-secondary);margin:12px 0 0;font-size:13px}.download-btn{color:#fff;background:var(--primary);border-radius:var(--radius-sm);cursor:pointer;border:none;width:100%;padding:14px 24px;font-size:16px;font-weight:600;transition:background .2s}.download-btn:hover:not(:disabled){background:var(--primary-hover)}.download-btn:disabled{background:var(--primary-disabled);cursor:not-allowed}.download-btn:focus-visible{outline:2px solid var(--primary);outline-offset:2px}