Could it be possible to make css selector affect other elements in the page without javascript? [duplicate]

Answer 1

You could try the General Sibling Selector(~) if the input boxes are next to each other.

Something like:

.a:focus {    background-color:Blue;}
.a:focus~.b {    background-color:Blue;}
.b:focus {    background-color:Yellow;}
.b:focus~.a {    background-color:Yellow;}

Note: Completely untested and a stab in the dark at best!