HTML Guide for border-style

border-style does not accept thick as a value; it should be set to values like solid, dashed, or dotted, while thick is a valid border-width value.

The CSS property border-style determines the style of the border, such as whether it is solid, dashed, double, etc.

Acceptable values include none, hidden, dotted, dashed, solid, double, groove, ridge, inset, and outset. The keyword thick is not valid for border-style; instead, it can be used with border-width to indicate a thicker border.

To achieve a thick solid border, set border-style to solid and border-width to thick.

Incorrect HTML Example:

<div style="border-style: thick;"></div>

Correct HTML Example:

<div style="border-style: solid; border-width: thick;"></div>

Or, if you want to specify a custom thickness:

<div style="border-style: solid; border-width: 5px;"></div>

The combination ensures that the border both displays in a solid style and is rendered at the desired thickness.