If you want to style child elements of a <div>
e.g. a <h1>
heading independent of other possible <h1>
elements outside of the container you can do this with a single CSS file only.
CSS offers the powerful > selector which let's you set up a rule for a child element.
In your case the container <div>
has an id of superdiv which is accessible like:
#superdiv
{
}
To access a child element - in your case the <h1>
tag - just do:
#superdiv > h1
{
}
Here's an example:
h1 {
color: #00ff00;
}
#superdiv {
background-color: #efefef;
border: 1px solid #ff0000;
}
#superdiv>h1 {
color: #0000ff;
}
<h1>Hello</h1>
<div id="superdiv">
My content
<h1>Hello</h1>
</div>