:root{--primary:#007bff;--success:#198754;--bg:#f0f2f5;--panel:#fff;--border:#d9dee5;--text:#212529;--muted:#6c757d;--input:#fff;--secondary:#6c757d}body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;background:var(--bg);color:var(--text);margin:0;padding:20px}.container{display:flex;gap:20px;max-width:1240px;margin:0 auto;background:var(--panel);border:1px solid var(--border);border-radius:12px;padding:20px}.controls{width:340px;flex-shrink:0;display:flex;flex-direction:column;gap:13px}.controls h1{font-size:24px;margin:0}.description{font-size:13px;color:var(--muted);line-height:1.7;margin:0}.upload-box{border:2px dashed var(--border);border-radius:14px;background:var(--bg);padding:22px;text-align:center;cursor:pointer}.upload-box.dragover{border-color:var(--primary);background:rgba(0,123,255,.06)}.upload-icon{font-size:38px}.upload-box p{margin:4px 0 12px;color:var(--muted)}.control-group{display:flex;flex-direction:column;gap:7px}.control-group label{font-size:14px;font-weight:600}select,input[type=number],input[type=color]{width:100%;box-sizing:border-box;border:1px solid var(--border);border-radius:8px;background:var(--input);color:var(--text);padding:9px 10px}input[type=color]{height:40px;padding:4px}input[type=range]{width:100%}button{width:100%;border:none;border-radius:8px;background:var(--primary);color:#fff;padding:10px 13px;cursor:pointer;font-weight:600}button:hover{background:#0b5ed7}.secondary{background:var(--secondary)}.secondary:hover{background:#5b6269}.color-row{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.color-btn{position:relative;background:var(--c);color:#222;border:1px solid var(--border);text-shadow:0 1px 2px rgba(255,255,255,.5)}.custom-size{display:grid;grid-template-columns:1fr 1fr;gap:10px}.switch-line{display:grid;grid-template-columns:auto 1fr;align-items:center}.switch-line input{width:18px;height:18px}.replace-options{display:grid;gap:12px;padding:12px;border:1px solid var(--border);border-radius:12px;background:rgba(0,0,0,.02)}.inline-row{display:grid;grid-template-columns:70px 1fr;gap:8px}.preview-panel{flex:1;min-width:0;display:grid;gap:16px;align-content:start}.preview-card{min-height:540px;background:var(--bg);border:1px solid var(--border);border-radius:12px;display:flex;align-items:center;justify-content:center;position:relative;overflow:auto;padding:20px;background-image:linear-gradient(45deg,rgba(0,0,0,.05) 25%,transparent 25%),linear-gradient(-45deg,rgba(0,0,0,.05) 25%,transparent 25%),linear-gradient(45deg,transparent 75%,rgba(0,0,0,.05) 75%),linear-gradient(-45deg,transparent 75%,rgba(0,0,0,.05) 75%);background-size:22px 22px;background-position:0 0,0 11px,11px -11px,-11px 0}#previewCanvas{max-width:100%;max-height:520px;box-shadow:0 8px 28px rgba(0,0,0,.18);background:#fff}#placeholderText{position:absolute;color:var(--muted);font-size:18px}.info-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.info-grid div{background:var(--bg);border:1px solid var(--border);border-radius:12px;padding:14px;text-align:center}.info-grid strong{display:block;font-size:18px}.info-grid span{font-size:12px;color:var(--muted)}.tips{margin:0;color:var(--muted);font-size:13px;line-height:1.7}.seo-note-wrap{max-width:1100px;margin:22px auto 0;padding:14px 18px 6px;box-sizing:border-box;border-top:1px solid rgba(148,163,184,.22);color:#64748b}.seo-note-item{margin:0 0 14px}.seo-note-item h2{margin:0 0 6px;font-size:13px;line-height:1.5;font-weight:600;color:#475569}.seo-note-item p,.seo-note-item li{font-size:12px;line-height:1.8;color:#64748b}.seo-note-item ol{margin:6px 0 0;padding-left:18px}body.dark-mode{--primary:#3d8bfd;--success:#20c997;--bg:#1e2128;--panel:#2a2e37;--border:#4a505f;--text:#e5e7eb;--muted:#9ca3af;--input:#373c47;--secondary:#4a505f}body.dark-mode button:hover{background:#4c9aff}body.dark-mode .secondary:hover{background:#5a6268}body.dark-mode .replace-options{background:rgba(255,255,255,.03)}body.dark-mode .preview-card{background-image:linear-gradient(45deg,rgba(255,255,255,.04) 25%,transparent 25%),linear-gradient(-45deg,rgba(255,255,255,.04) 25%,transparent 25%),linear-gradient(45deg,transparent 75%,rgba(255,255,255,.04) 75%),linear-gradient(-45deg,transparent 75%,rgba(255,255,255,.04) 75%)}body.dark-mode .seo-note-wrap{border-top-color:rgba(148,163,184,.16)}body.dark-mode .seo-note-item h2{color:#cbd5e1}body.dark-mode .seo-note-item p,body.dark-mode .seo-note-item li{color:#94a3b8}@media(max-width:960px){body{padding:10px}.container{flex-direction:column;padding:14px}.controls{width:100%}.preview-card{min-height:360px}.info-grid{grid-template-columns:1fr}.custom-size{grid-template-columns:1fr}}@media(max-width:520px){.color-row{grid-template-columns:repeat(2,1fr)}}