border-block-start
A shorthand for setting the width, style, and color of the 'start' side border in the block dimension. Effectively styles the top border in horizontal writing modes.
Quick example
main {
/* Logical equivalent of border-top */
border-block-start: 2px solid #000;
}Quick facts
Initial value
See individual propertiesInherited
No
Applies to
all elements
Values
border-top-widthborder-top-style border-block-start Browser Support
Widely available Since 2021 95% global usage
This feature is well established and works across many devices and browser versions. It has been available across browsers since 2021.
Safe to use without fallbacks.
69+
41+
12.1+
79+