Logical properties for sizing
In this guide we will explain the flow-relative mappings between physical dimension properties and logical properties used for sizing elements on our pages.
When specifying the size of an item, the Logical Properties and Values specification gives you the ability to indicate sizing as it relates to the flow of text (inline and block) rather than physical sizing which relates to the physical dimensions of horizontal and vertical (e.g. left and right). While these flow relative mappings may well become the default for many of us, in a design you may well use both physical and logical sizing. You might want some features to always relate to the physical dimensions whatever the writing mode.
Mappings for dimensions
The table below provides mappings between logical and physical properties. These mappings assume that you are in a horizontal-tb
writing mode, such as English or Arabic, in which case width
would be mapped to inline-size
.
If you were in a vertical writing mode then inline-size
would be mapped to height
.
Logical Property | Physical Property |
---|---|
inline-size |
width |
block-size |
height |
min-inline-size |
min-width |
min-block-size |
min-height |
max-inline-size |
max-width |
max-block-size |
max-height |
Width and height example
The logical mappings for width
and height
are inline-size
, which sets the length in the inline dimension and block-size
, which sets the length in the block dimension. When working in English, replacing width
with inline-size
and height
with block-size
will give the same layout.
In the live example below I have set the Writing Mode to horizontal-tb
. Change it to vertical-rl
and you will see that the first example — which uses width
and height
— remains the same size in each dimension, despite the text becoming vertical. The second example — which uses inline-size
and block-size
— will follow the text direction as if the entire block has rotated.
Min-width and min-height example
There are also mappings for min-width
and min-height
— these are min-inline-size
and min-block-size
. These work in the same way as the inline-size
and block-size
properties, but setting a minimum rather than a fixed size.
Try changing the example below to vertical-rl
, as with the first example, to see the effect it has. I am using min-height
in the first example and min-block-size
in the second.
Max-width and max-height example
Finally you can use max-inline-size
and max-block-size
as logical replacements for max-width
and max-height
. Try playing with the below example in the same way as before.
Logical keywords for resize
The resize
property sets whether or not an item can be resized and has physical values of horizontal
and vertical
. The resize
property also has logical keyword values. Using resize: inline
allows resizing in the inline dimension and resize: block
allow resizing in the block dimension.
The keyword value of both
for the resize property works whether you are thinking physically or logically. It sets both dimensions at once. Try playing with the below example.