1.代码：
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>01triangle</title><style>.box {width: 0px;height: 0px;/* background-color: red; */border: 50px solid transparent;border-left: 50px solid rgb(255, 174, 0)}</style>
</head><body><div class="box"></div>
</body></html>2.效果图
