Using regular expression in css?

Question

I have an html page with divs that have id(s) of the form s1, s2 and so on.

Answer 1

An ID is meant to identify the element uniquely. Any styles applied to it should also be unique to that element. If you have styles you want to apply to many elements, you should add a class to them all, rather than relying on ID selectors...

   
...
   
...
   ...

and

.sec {
    ...
}

Or in your specific case you could select all divisions inside your parent container, if nothing else is inside it, like so:

#sections > div {
    ...
}