Here my codepen: https://codepen.io/wongest/pen/bGyXmbo
.box { width: 500px; height: 500px; border: 1px solid #000; display: flex;}.box1 { flex: 1; height: 500px; background-color: blue; overflow: clip;}.box1-1 { width: 700px; height: 100px; background-color: red;}.box2 { width: 300px;}<div class="box"><div class="box1"><div class="box1-1">box1-1</div></div><div class="box2">box2</div></div>But the box1-1 is overflow the box1
And if css box1 change this: overflow: hidden, it work!Why?
why overflow: clip not working in flexbox