If you are thinking of becoming a web designer then one of the first skills you will want to master is CSS. CSS effects the layout properties of each page. It is used to tell different elements where they need to be on the page and how they should be displayed on different devices. It should also be used to set fonts, colours and sizes of images etc.
You do not need to memorise every single CSS command and you can often look them up very easily, but it is very handy to master a few of that you will use often. It is worth trying to understand how the CSS elements work and properties that you can assign to them. Understanding how the page is laid out using CSS will allow you to solve problems easier and get your site working as it should do. It is also important to keep up to date on CSS, as new browsers and browser versions are released new CSS styles may also be released and older ones no longer supported. If you design a site based only on one browser then you may find it doesn’t work when visitors are using a different one.