CSS not working in style.css but do in custom css

Hi there,

i was wondering why sometimes my CSS will not do anything if i add them to my style.css in my childtheme but do work if i add them (the exact same css) in my custom css plugin.
Example: This piece of CSS works in the pluging
`.menu-toggle {
display: none !important;
}
.mobile-menu {
display:none !important;
}’

But it will not work in my style.css

The style.css should be setup correctly because other css works fine.

Thanks for your time,
Sjoerd