Outline thickness

outline-width

Set the thickness of an element's outline ("outside-the-box" border).

Property values

The width of this property does not affect the size of the element, or the size of nearby elements. Wide outlines may cross over nearby elements.

Unlike many other similar properties, the outline-width property does not have corresponding top, right, bottom and left properties. Outline-width rules can only be set for all four sides at once.

Use any of these special keyword values to set the outline width:

thin Typically this means 1px, but it's not formally defined as such
medium Typically this means 3px, but it's not formally defined as such
think Typically this means 5px, but it's not formally defined as such

Or use any of these font-relative typographic units to set the outline 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

outline-width: 2px;
outline-width

style > framing > outline-widthOutline thickness

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