How to use CSS calc() with an element's height

Question

I was studying ways to make a hexagon with just CSS, and found a solution that gives me regular hexagons based on the width:

.hexagon {   height: 100%;   width: calc(100% * 0.57735);   display: inline-block; } 

However, the code works by generating new rectangles based on the parent element's width. I was searching for a way to calculate the width based on the parent's height.

Is there a way to use an element's height property instead of width for calc()? (I'm not looking into using vh since the nearest parent won't always be the viewport). I googled around and could not find an answer.

Answer 1

I think you are trying to run script in a css syntax, which is NOT POSSIBLE.

calc() can do basic math operation with absolute values, it cannot find the height of an element and then perform math on it.

Answer 2

You can circumvent the problem using an intermediary: CSS variables, which is the only data "outside" the curly brackets, as it were.

If the parent's width is also dynamic or dependant on other value, use another var for that. Just as an example so you can see the syntaxis, it'd look something like this:

:root {   --hex-parent-height: 10px; }  .hexagon.parent {   /* ... */   width: var(--hex-parent-height); }  .hexagon {   height: 100%;   width: calc(100% * var(--hex-parent-height));   display: inline-block; } 

CSS Variables have two types of scopes: global and local. Local vars will only work logically within the same selector, but global vars are the same through all your CSS. Declaring one or more variables globally is done through the root block, as shown in the code example.

Retrieving a var value as you can see is as easy as using the var() CSS function, which in case you don't know, has a very nice fallback feature.

For example, if you were to set --hex-parent-height dynamically and something goes wrong and the var is left unset, you may insert a default value to minimize the damages, like so: var(--hex-parent-height, 10px)