the following figure:
when getting focus, how to add a border, to input. This boder is thicker than the default border. Note that this is not the effect of css shadow, there is no feathering.
I think of putting a div, thick border on the outside of input and adding it to div, but this needs to be operated with js, is it possible to use pure css to achieve this effect? For example, pseudo-classes like input:focus are implemented.