SaltyCrane Blog — Notes on JavaScript and web development

How height is set in CSS

Here are some CSS experiments to test when elements adjust to the height of their container and when they adjust to the height of their content. The script to generate the experiments is on github and the results are shown below. See also my companion page on CSS width.

By default, elements adjust to height of their container when they are
By default, elements adjust to the height of their content when they are
Some elements can be made to adjust to the height of their container by
Some elements can be made to adjust to the height of their content by
Some miscellaneous cases:

See also

Block containers

Block containers - elements in block containers adjust to the height of their content by default
#container-1a
#example-1a
#content-1a
HTML
<div id="container-1a"> <div id="example-1a"> <div id="content-1a" /> </div> </div>
CSS
#container-1a { display: block; /* default */ height: 400px; } #example-1a {} #content-1a { height: 80px; }
Block containers, tall content - elements in block containers adjust to the height of their content even when the content is taller than the container
#container-1b
#example-1b
#content-1b
HTML
<div id="container-1b"> <div id="example-1b"> <div id="content-1b" /> </div> </div>
CSS
#container-1b { display: block; /* default */ height: 400px; } #example-1b {} #content-1b { height: 420px; }
Block elements, height 100% - block elements expand to the height of their container if height is set to 100%
#container-1c
#example-1c
#content-1c
HTML
<div id="container-1c"> <div id="example-1c"> <div id="content-1c" /> </div> </div>
CSS
#container-1c { display: block; /* default */ height: 400px; } #example-1c { height: 100%; } #content-1c { height: 80px; }
Block elements, tall content, height 100% - block elements contract to the height of their container if height is set to 100%
#container-1d
#example-1d
#content-1d
HTML
<div id="container-1d"> <div id="example-1d"> <div id="content-1d" /> </div> </div>
CSS
#container-1d { display: block; /* default */ height: 400px; } #example-1d { height: 100%; } #content-1d { height: 420px; }

Flex row containers

Flex row container - elements in flex row containers expand to the height of their container by default
#container-3a
#example-3a
#content-3a
HTML
<div id="container-3a"> <div id="example-3a"> <div id="content-3a" /> </div> </div>
CSS
#container-3a { align-items: normal; /* default - behaves as stretch in this case */ display: flex; flex-direction: row; /* default */ height: 400px; } #example-3a {} #content-3a { height: 80px; }
Flex row container, tall content - elements in flex row containers contract to the height of their container by default
#container-3b
#example-3b
#content-3b
HTML
<div id="container-3b"> <div id="example-3b"> <div id="content-3b" /> </div> </div>
CSS
#container-3b { align-items: normal; /* default - behaves as stretch in this case */ display: flex; flex-direction: row; /* default */ height: 400px; } #example-3b {} #content-3b { height: 420px; }
Flex row container, align-items set - elements in flex row containers adjust to the height of their content if align-items is set to something other than stretch
#container-3c
#example-3c
#content-3c
HTML
<div id="container-3c"> <div id="example-3c"> <div id="content-3c" /> </div> </div>
CSS
#container-3c { align-items: flex-start; display: flex; flex-direction: row; /* default */ height: 400px; } #example-3c {} #content-3c { height: 80px; }
Flex row container, align-items set, tall content - elements in flex row containers adjust to the height of their content if align-items is set to something other than stretch
#container-3d
#example-3d
#content-3d
HTML
<div id="container-3d"> <div id="example-3d"> <div id="content-3d" /> </div> </div>
CSS
#container-3d { align-items: flex-start; display: flex; flex-direction: row; /* default */ height: 400px; } #example-3d {} #content-3d { height: 420px; }

Flex column containers

Flex column container - elements in flex columns containers adjust to the height of the content by default
#container-4a
#example-4a
#content-4a
HTML
<div id="container-4a"> <div id="example-4a"> <div id="content-4a" /> </div> </div>
CSS
#container-4a { display: flex; flex-direction: column; justify-content: normal; /* default */ height: 400px; } #example-4a {} #content-4a { height: 80px; }
Flex column container, tall content - elements in flex columns containers adjust to the height of their content even for tall content
#container-4b
#example-4b
#content-4b
HTML
<div id="container-4b"> <div id="example-4b"> <div id="content-4b" /> </div> </div>
CSS
#container-4b { display: flex; flex-direction: column; justify-content: normal; /* default */ height: 400px; } #example-4b {} #content-4b { height: 420px; }
Flex column container, height: 100% - elements in flex column containers expand to the height of their container if height is set to 100%
#container-4c
#example-4c
#content-4c
HTML
<div id="container-4c"> <div id="example-4c"> <div id="content-4c" /> </div> </div>
CSS
#container-4c { display: flex; flex-direction: column; justify-content: normal; /* default */ height: 400px; } #example-4c { height: 100%; } #content-4c { height: 80px; }
Flex column container, height: 100%, tall content - elements in flex column containers contract to the height of their container if height is set to 100%
#container-4d
#example-4d
#content-4d
HTML
<div id="container-4d"> <div id="example-4d"> <div id="content-4d" /> </div> </div>
CSS
#container-4d { display: flex; flex-direction: column; justify-content: normal; /* default */ height: 400px; } #example-4d { height: 100%; } #content-4d { height: 420px; }
Flex column container, flex-grow - elements in flex column containers expand to the height of their container when flex-grow is set to 1
#container-4e
#example-4e
#content-4e
HTML
<div id="container-4e"> <div id="example-4e"> <div id="content-4e" /> </div> </div>
CSS
#container-4e { display: flex; flex-direction: column; justify-content: normal; /* default */ height: 400px; } #example-4e { flex-grow: 1; } #content-4e { height: 80px; }
Flex column container, flex-grow, tall content - elements in flex column containers expand to the height of their content when flex-grow is set to 1
#container-4f
#example-4f
#content-4f
HTML
<div id="container-4f"> <div id="example-4f"> <div id="content-4f" /> </div> </div>
CSS
#container-4f { display: flex; flex-direction: column; justify-content: normal; /* default */ height: 400px; } #example-4f { flex-grow: 1; } #content-4f { height: 420px; }

Grid containers

Grid container - elements in grid containers expand to the height of the container by default
#container-5a
#example-5a
#content-5a
HTML
<div id="container-5a"> <div id="example-5a"> <div id="content-5a" /> </div> </div>
CSS
#container-5a { align-items: normal; /* default - behaves like stretch in this case */ display: grid; height: 400px; } #example-5a {} #content-5a { height: 80px; }
Grid container, tall content - elements with tall content in grid containers expand to the height of the content
#container-5b
#example-5b
#content-5b
HTML
<div id="container-5b"> <div id="example-5b"> <div id="content-5b" /> </div> </div>
CSS
#container-5b { align-items: normal; /* default - behaves like stretch in this case */ display: grid; height: 400px; } #example-5b {} #content-5b { height: 420px; }
Grid container, tall content, height 100% - surprisingly, setting height to 100% does not contract an element's height to the height of its container. The element adjusts to the height of the content.
#container-5c
#example-5c
#content-5c
HTML
<div id="container-5c"> <div id="example-5c"> <div id="content-5c" /> </div> </div>
CSS
#container-5c { align-items: normal; /* default - behaves like stretch in this case */ display: grid; height: 400px; } #example-5c { height: 100%; } #content-5c { height: 420px; }
Grid container, tall content, overflow - elements with tall content in grid containers adjust to the height of the container if overflow is set to something other than visible
#container-5d
#example-5d
#content-5d
HTML
<div id="container-5d"> <div id="example-5d"> <div id="content-5d" /> </div> </div>
CSS
#container-5d { align-items: normal; /* default - behaves like stretch in this case */ display: grid; height: 400px; } #example-5d { overflow: auto; } #content-5d { height: 420px; }
Grid container, align-items - if a grid container sets align-items to something other than stretch (the default), then the element will adjust to the height of the content MDN docs on align-items.
#container-5e
#example-5e
#content-5e
HTML
<div id="container-5e"> <div id="example-5e"> <div id="content-5e" /> </div> </div>
CSS
#container-5e { align-items: start; display: grid; height: 400px; } #example-5e {} #content-5e { height: 80px; }
Grid container, align-items, tall content - elements with tall content in grid containers expand to the height of the content
#container-5f
#example-5f
#content-5f
HTML
<div id="container-5f"> <div id="example-5f"> <div id="content-5f" /> </div> </div>
CSS
#container-5f { align-items: start; display: grid; height: 400px; } #example-5f {} #content-5f { height: 420px; }
Grid container, align-items, tall content, overflow - elements with tall content in grid containers expand to the height of the content even if overflow is set
#container-5g
#example-5g
#content-5g
HTML
<div id="container-5g"> <div id="example-5g"> <div id="content-5g" /> </div> </div>
CSS
#container-5g { align-items: start; display: grid; height: 400px; } #example-5g { overflow: auto; } #content-5g { height: 420px; }

Absolute positioning

Absolutely positioned -
#container-6a
#example-6a
#content-6a
HTML
<div id="container-6a"> <div id="example-6a"> <div id="content-6a" /> </div> </div>
CSS
#container-6a { display: block; /* default */ position: relative; height: 400px; } #example-6a { position: absolute; } #content-6a { height: 80px; }
Absolutely positioned, tall content -
#container-6b
#example-6b
#content-6b
HTML
<div id="container-6b"> <div id="example-6b"> <div id="content-6b" /> </div> </div>
CSS
#container-6b { display: block; /* default */ position: relative; height: 400px; } #example-6b { position: absolute; } #content-6b { height: 420px; }
Absolutely positioned, height 100% -
#container-6c
#example-6c
#content-6c
HTML
<div id="container-6c"> <div id="example-6c"> <div id="content-6c" /> </div> </div>
CSS
#container-6c { display: block; /* default */ position: relative; height: 400px; } #example-6c { height: 100%; position: absolute; } #content-6c { height: 80px; }
Absolutely positioned, height 100%, tall content -
#container-6d
#example-6d
#content-6d
HTML
<div id="container-6d"> <div id="example-6d"> <div id="content-6d" /> </div> </div>
CSS
#container-6d { display: block; /* default */ position: relative; height: 400px; } #example-6d { height: 100%; position: absolute; } #content-6d { height: 420px; }

Floated elements

Floated elements - elements that set float adjust to the height of their content. MDN docs on float.
#container-7a
#example-7a
#content-7a
HTML
<div id="container-7a"> <div id="example-7a"> <div id="content-7a" /> </div> </div>
CSS
#container-7a { display: block; /* default */ height: 400px; } #example-7a { float: left; } #content-7a { height: 80px; }
Floated elements, tall content - elements that set float adjust to the height of their content
#container-7b
#example-7b
#content-7b
HTML
<div id="container-7b"> <div id="example-7b"> <div id="content-7b" /> </div> </div>
CSS
#container-7b { display: block; /* default */ height: 400px; } #example-7b { float: left; } #content-7b { height: 420px; }
Floated elements, height 100% -
#container-7c
#example-7c
#content-7c
HTML
<div id="container-7c"> <div id="example-7c"> <div id="content-7c" /> </div> </div>
CSS
#container-7c { display: block; /* default */ height: 400px; } #example-7c { float: left; height: 100%; } #content-7c { height: 80px; }
Floated elements, height 100%, tall content -
#container-7d
#example-7d
#content-7d
HTML
<div id="container-7d"> <div id="example-7d"> <div id="content-7d" /> </div> </div>
CSS
#container-7d { display: block; /* default */ height: 400px; } #example-7d { float: left; height: 100%; } #content-7d { height: 420px; }

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