CSS unit is a type of data with which we can define measurements, and it looks like this:
max-height: 150px;Alternatively, it could also look like this:
transform: rotate(45deg);There is no space between the number and the unit.
In most cases, the unit isn't required after the number 0 (zero).
There are several types of length units, such as described in the following explanations.
They are dependent on another element's length (usually, a parent element in the DOM) that relates directly to the element in question. When the other element's length changes, the length of the element in question maintains the defined proportion. In other words, there is no need to declare the length of the child element again.