[shka]

I don't know if I understood your problem correct. You mean:

click in input-box (in your pic the title field of advanced editor, but also every other input field like login data with your demo account, edit and send a pm ) results to white background and white text?

Your aim: other text color?

There is no stylevar for. In template "vbulletin-formcontrols.css" there is only a definition for background

.formcontrols .blockrow input.textbox:focus,
.formcontrols .blockrow textarea:focus {
	background: {vb:stylevar input_focus_background};
}

Two solutions:
A. Edit "vbulletin-formcontrols.css" to

.formcontrols .blockrow input.textbox:focus,
.formcontrols .blockrow textarea:focus {
	background: {vb:stylevar input_focus_background};
       color: #888888;
}

B. Go to template "additional.css" and add

.formcontrols .blockrow input.textbox:focus,
.formcontrols .blockrow textarea:focus {
       color: #888888;
}

Change #888888 to a color of your choice.