The difference is defined in somewhat vague terms in the CSS 2.1 specification :
groove
A border looks like it is carved on canvas.
crest
The opposite of the βgrooveβ: the border looks as if it comes out of the canvas.
This allows various interpretations and implementations, and the visual effect is often not so clear. It tends to be clearer if the border is relatively wide. Browsers typically use two different colors to create the impression of a declared border color and a lighter color. This should be consistent with the idea of ββa groove or ridge border when the light comes from the direction of the upper left corner. Example:
<style> span { border: solid red 10px } .groove { border-style: groove } .ridge { border-style: ridge } </style> <span class=groove>groove</span> <span class=ridge>ridge</span>
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