It seems that it is not easy to implement using border. Finally, gradients and pseudo elements are used to achieve the above effect. I just don’t know what browser version you want to be compatible with.
For specific code, please refer to: http://codepen.io/yuezk/pen/xwQweW
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It seems that it is not easy to implement using border. Finally, gradients and pseudo elements are used to achieve the above effect. I just don’t know what browser version you want to be compatible with.
For specific code, please refer to: http://codepen.io/yuezk/pen/xwQweW