Actually there is…. but it uses a CSS3 gradient which can be a bit confusing at first. But first, you will want to make sure you use a child theme for any modifications you perform. In the theme files is a folder called child-theme and in that is an installable child theme for Preference Lite. Best to install that, activate it and then refer to http://codex.wordpress.org/Child_Themes for more info about this…
Now with that out of the way, in the theme is a folder “css” and in that is menu.css. The part that styled the toggle button is found near the top of the file around line 5 and starts with this:
/* Main Menu Toggle */
There’s three parts for the effect, the normal state, hover, and active. But basically the colour part (or gradient part looks like this:
color: #fff;
background-color: #e6e6e6;
background-repeat: repeat-x;
background-color: #618b9b;
background-image: -moz-linear-gradient(top, #8db9c9, #618b9b);
background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#618b9b), to(#8db9c9));
background-image: -webkit-linear-gradient(top, #8db9c9, #618b9b);
background-image: -o-linear-gradient(top, #8db9c9, #618b9b);
background-image: linear-gradient(to bottom, #8db9c9, #618b9b);
To get a new gradient colour, I use this online tool:
Make a Gradient
You can of course decide not to use a gradient and just use a background colour only. Simply remove the gradient css code and replace it with something like this:
background-color: #e6e6e6;
Then of course, you can change the font size there and colour of the text too.