:root {
  --bg: #f6f7f9;
  --panel: #fff;
  --muted: #666;
  --accent: #0b66ff;
  --danger: #b00020;
  --pad: 12px;
}  

*{box-sizing:border-box;font-family:Inter,system-ui,Segoe UI,Roboto,Arial;}

body{margin:0;background:var(--bg);color:#222;}
header{padding:16px;background:#fff;border-bottom:1px solid #e6e9ee;}
.header h1{margin:0;}
.subtitle{font-size:13px;color:var(--muted);margin-top:6px;}

#main{display:flex;gap:16px;padding:16px;align-items:flex-start;}
#controls{width:360px;background:var(--panel);border:1px solid #e6e9ee;border-radius:8px;padding:12px;height:calc(100vh - 120px);overflow:auto;}
#preview{flex:1;background:var(--panel);border:1px solid #e6e9ee;border-radius:8px;padding:12px;height:calc(100vh - 120px);display:flex;flex-direction:column;}

.panel{margin-bottom:12px;border-bottom:1px dashed #eee;padding-bottom:8px;}
.panel h2{margin:0 0 8px 0;font-size:14px;}
label{display:block;font-size:13px;margin-top:8px;}
input[type=range]{width:100%;margin-top:6px;}
select, input[type=text], input#presetName{width:100%;padding:8px;border:1px solid #d7dbe0;border-radius:6px;margin-top:6px;}
button{background:var(--accent);color:#fff;border:none;padding:8px 10px;border-radius:6px;cursor:pointer;margin-top:8px;}
button:active{transform:translateY(1px);}
.note.small{font-size:12px;color:var(--muted);margin-top:6px;}

.canvas-wrap{flex:1;display:flex;align-items:center;justify-content:center;padding:8px;border-radius:6px;background:#fff;border:1px dashed #eef2f8;}
canvas{max-width:100%;height:auto;border-radius:4px;background:#fff;display:block;}

.metrics{display:flex;gap:12px;flex-wrap:wrap;font-size:13px;margin-bottom:8px;}
.validation{min-height:34px;color:var(--danger);font-weight:700;padding:6px 0;}

@media (max-width:920px){  
  #main{flex-direction:column;padding:8px;}
  #controls{width:100%;height:auto;}
  #preview{width:100%;height:auto;}
}