* { box-sizing: border-box; }
html,body { height:100%; margin:0; font-family: Arial, Helvetica, sans-serif; }
.toolbar { padding:10px; background:#f6f6f6; display:flex; gap:12px; align-items:center; border-bottom:1px solid #e3e3e3; }
.canvas-wrap { height: calc(100% - 56px); display:flex; align-items:center; justify-content:center; position:relative; }
canvas { border:1px solid #ddd; background:#fff; width:90%; height:80%; touch-action: none; }
.hint { position:absolute; bottom:14px; right:18px; color:#666; font-size:13px }