Custom border thickness
border-image-width
Specify how to scale the source image regions into the custom border's thickness.
Property values
This property defines how the border image slices are rendered. The sizes specified here do not have to be equal to the region sizes created with the border-image-slice rule. The nine images slices may be expanded or contracted from their original size in this process.
In order for this property to be effective, the border-width property must be specified concurrently. If the border-image-width is greater than the border-width, it will spill over into the interior of the element.
This property expects anywhere from one to four values, with their interpretation as follows:
| number of values | sides effected |
|---|---|
| 1 value | Sets all four sides: top, right, bottom, left |
| 2 values | 1st value: top and bottom edges 2nd value: right and left edges |
| 3 values | 1st value: top edge 2nd value: right and left edges 3rd value: bottom edge |
| 4 values | 1st value: top edge 2nd value: right edge 3rd value: bottom edge 4th value: left edge |
Use any of these font-relative typographic units to set the border-image-width:
| em | em | The font-size of the current font |
| rem | relative em | The font-size of the <html> element |
| lh | line height | The line-height of the current font |
| rlh | relative line height | The line-height of the <html> element |
| cap | cap height | The nominal height of the current font's capital letters |
| ex | "x" | The height of the current font's "x" glyph |
| ch | "0" | The advance measure (the width) of the current font's "0" glyph |
| ic | ideograph count | The advance measure (the width) of the current font's "水" ideograph |
Or use any of these fixed size units which are independent of the current font:
| in | inch | A size equal 96px |
| px | pixels | A size equal to 1/96 inch |
| pt | point | A size equal 1in/72 = 1.33px |
| pc | pica | A size equal 1in/6 = 12pt = 16px |
| cm | centimeter | A size equal to 96px/2.54 = 37.8px |
| mm | millimeter | A size equal to 96px/25.4 = 3.8px |
| Q | quarter millimeter | A size equal to 96px/1016 = 0.94px |
Examples
/* identical border width and border-image width */
border-width: 10px;
border-image-width: 10px;
/* border-image width intrudes into the interior by 9 pixels */
border-width: 1px;
border-image-width: 10px;