线条宽度 1 2 3 4 5 6 7 8 9 10 颜色
* { margin:0; padding:0; } div { width:400px; height:650px; border:1px solid black; box-shadow:4px 4px 4px grey; /*margin:auto; */ } canvas { border-bottom:2px solid red; } #btn { margin-left:30px; } span { margin-left:30px; }