Highlighting is a tried-and-true method of isolating details in a body of text. At a glance, more important information is easily distinguished from the less important content. Many people know you can highlight passages in PDF files. But many people also clip a lot of web content — web archives, formatted notes, and HTML pages — and still have the need for highlighting. DEVONthink has that option covered too.
When you’re reading a clipped web page in DEVONthink, select some text and choose Format > Highlight (or press ⇧⌘L) and the text will be highlighted with the current highlight color. When you save the page, the highlights will be preserved.