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- Property
- border-top-width
- Values
- thin, medium, thick, <length>
- Initial
- 'medium'
- Inherited
- no
This property sets the width of an element's top border. The width of the keyword values are UA dependent, but the following holds: 'thin' <= 'medium' <= 'thick'.
The keyword widths are constant throughout a document:
H1 { border: solid thick red }
P { border: solid thick blue }
In the example above, 'H1' and 'P' elements will have the same border width regardless of font size. To achieve relative widths, the 'em' unit can be used:
H1 { border: solid 0.5em }
Border widths cannot be negative.