CSS3 border凹陷该如何编写？

Question

本人新手，请问各位大神，如此，该如何编写CSS3 ？ （我说的是蓝色的部分） 谢谢了~~

ringa_lee · Answer

My idea: absolute positioning + after/before pseudo-class implementation, the approximate effect is as follows:

TZ can refer to the demo given and modify it yourself: online demo

天蓬老师 · Answer

If you change your mind, you can set the margin of the circle to the background color, and then cover the right side, so that it looks like a concave effect.

怪我咯 · Answer

First of all, let me correct the answer on the first floor. After/before are pseudo-elements rather than pseudo-classes. This is very important. Don’t confuse this. If it were me, I would cover the strip with a big circle and then a small circle. Just be nice

巴扎黑 · Answer

css