Hi Gelli,
Best practice says use unique selector or a combination of selector i.e id and class to avoid overwrite the existing CSS.
Example: Applying custom css to specific page and there
HTML component inside the body.
<body id="wizard" class="workflow-page" >
<div>
<p>This my text</p>
<span></span>
</div>
</div>
/**** your custom CSS *****/
#wizard.workflow-page {
p {
font-size: 20px;
}
a {
color: green;
}
}
Kentico having one more capability to adding CSS stylesheets to individual page components for more reference checkout this document.