There are several mistakes I find from time to time over again which I would like to clarify:


When using float: left;, display: block; is not required anymore as every element which is floated is automatically a block element.


With modern HTML5 we can use the html attribute``hidden=”hidden”`` which is a softer display: none; and can easy be overwritten using css or JavaScript. This attribute is ideal for hiding elements which should be later displayed using JavaScript, as there is no delay in which the element is hidden as for typical dynamic execution.