Fix CSS properties

Important things to remember about CSS

- Space between selectors means you are selecting children, no space means you are adding specificity to your selection
    
    `button .selected` means "something with `class="selected"` that has a `<button>` as it's parent"

    `button.selected` means "A `<button>` with `class="selected"`"

- CSS properties use dashes in their names. In javascript libraries, we generally refer to these attributes using underscores since dashes are subtraction operators in javascript