css – submit button of “site-reviews plugin

Good morning,

I am having problems with the submit button of “site-reviews plugin.
I cannot get it to make the text in the button white with a css command.

Below is the css code I am using. It understands the yellow color I set at “hover” but it does not output the white text in the button.

Am I overlooking something?
Who can help me?

.glsr-review-form button.glsr-button {
color: #ffffff; /* Witte tekstkleur / background-color: #55b0dc; / Standaard achtergrondkleur */
border-radius: 0px;
box-shadow: none;
text-decoration: none;

font-size: 1.025em;

}

.glsr-review-form button.glsr-button:hover {
background-color: #2e69af; /* Achtergrondkleur bij hover / color: #fafd0d; / Witte tekstkleur bij hover */
}

The page I need help with: [log in to see the link]