PUBLIC MARKS from decembre with tag grid

Let's take a look at what it takes to build a grid overlay with CSS. It will be responsive, easily customizable and make heavy use of CSS variables (known more accurately as "CSS custom properties"). If you aren't familiar with custom properties, I'd highly recommend reading What is the difference between CSS variables and preprocessor variables? and watching Lea Verou's enlighting talk on using them. This grid overlay that we're building will consider a developer tool, as in, a tool just for us, not really our users. So, let's not worry too much about browser support (If you do care, check out caniuse… data on custom properties). While it's impossible to preprocess custom properties to behave exactly the same as native support, if you use them just like you would preprocessor variables, tools like the postCSS plugin cssnext can transform them into CSS compliant with older browsers.