How can change the color of the buttons when hovering over them in the toolbox?

Hello! I want to change the color of the buttons when hovering over them in the toolbox, I have managed to change the background-color but for some reason I cannot change the color of the actual button. Here's an image to show it:

I changed the background to yellow but the button is white still. I used this code:

.devtools-togglebutton:hover, .devtools-button:hover {
  background: yellow !important;
}

Hope someone can help. Thanks!

(Sorry for any mistakes it's my first time using Lemmy)