*{margin:0;padding:0;box-sizing:border-box}
:root{--bg:#0d1117;--surface:#161b22;--border:#30363d;--text:#c9d1d9;--text-dim:#8b949e;--accent:#58a6ff;--code-bg:#1f2937}
body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif;background:var(--bg);color:var(--text);height:100vh;overflow:hidden}
.app{display:flex;flex-direction:column;height:100vh}
header{display:flex;align-items:center;justify-content:space-between;padding:12px 20px;background:var(--surface);border-bottom:1px solid var(--border);flex-shrink:0}
header h1{font-size:1.1rem;font-weight:600}
.header-actions{display:flex;align-items:center;gap:10px}
.header-actions button{background:transparent;border:1px solid var(--border);color:var(--text-dim);padding:5px 12px;border-radius:6px;cursor:pointer;font-size:.8rem;transition:.2s}
.header-actions button:hover{background:rgba(255,255,255,.05);color:var(--text);border-color:var(--text-dim)}
.word-count{font-size:.8rem;color:var(--text-dim);min-width:40px;text-align:right}
main{display:flex;flex:1;overflow:hidden}
.panel{display:flex;flex-direction:column;flex:1;overflow:hidden}
.panel-header{display:flex;align-items:center;justify-content:space-between;padding:8px 16px;background:var(--surface);border-bottom:1px solid var(--border);flex-shrink:0}
.panel-title{font-size:.75rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em;color:var(--text-dim)}
.panel-badge{font-size:.7rem;color:var(--text-dim);background:rgba(255,255,255,.04);padding:2px 8px;border-radius:4px}
#editor{flex:1;background:var(--bg);color:var(--text);border:none;outline:none;resize:none;padding:20px;font-family:'JetBrains Mono','Fira Code',monospace;font-size:14px;line-height:1.7;tab-size:2}
#editor::placeholder{color:#484f58}
.divider{width:4px;cursor:col-resize;background:var(--border);flex-shrink:0;transition:background .15s;position:relative}
.divider:hover,.divider:active{background:var(--accent)}
.divider::after{content:'';position:absolute;left:-4px;right:-4px;top:0;bottom:0}
.preview{flex:1;padding:20px 28px;overflow-y:auto;line-height:1.7;font-size:15px}
.preview h1{font-size:1.8rem;font-weight:700;margin:0 0 16px;padding-bottom:8px;border-bottom:1px solid var(--border)}
.preview h2{font-size:1.4rem;font-weight:600;margin:28px 0 12px}
.preview h3{font-size:1.2rem;font-weight:600;margin:24px 0 8px}
.preview p{margin-bottom:16px}
.preview a{color:var(--accent);text-decoration:none}
.preview a:hover{text-decoration:underline}
.preview strong{font-weight:600;color:#f0f6fc}
.preview code{background:var(--code-bg);padding:2px 6px;border-radius:4px;font-size:.85em;font-family:'JetBrains Mono',monospace}
.preview pre{background:var(--code-bg);padding:16px;border-radius:8px;overflow-x:auto;margin-bottom:16px;border:1px solid var(--border)}
.preview pre code{background:none;padding:0}
.preview blockquote{border-left:3px solid var(--accent);padding:8px 16px;margin:16px 0;background:rgba(88,166,255,.04);border-radius:0 6px 6px 0;color:var(--text-dim)}
.preview ul,.preview ol{padding-left:24px;margin-bottom:16px}
.preview li{margin-bottom:4px}
.preview hr{border:none;border-top:1px solid var(--border);margin:24px 0}
.preview table{width:100%;border-collapse:collapse;margin-bottom:16px}
.preview th,.preview td{border:1px solid var(--border);padding:8px 12px;text-align:left}
.preview th{background:var(--surface);font-weight:600}
.preview img{max-width:100%;border-radius:8px}
.preview::-webkit-scrollbar{width:8px}
.preview::-webkit-scrollbar-track{background:transparent}
.preview::-webkit-scrollbar-thumb{background:var(--border);border-radius:4px}
@media(max-width:640px){main{flex-direction:column}.divider{width:100%;height:4px;cursor:row-resize}#editor{font-size:13px;padding:12px}.preview{padding:12px 16px}}