G-Web dark-theme: New-mail form: Header-buttons unreadable.

[umgfoin]

Current changes to theming and styles are causing unreadable GUI-controls in the dark-theme:
New-mail form:
Header-buttons (TO:, CC, BCC etc.) are drawn with white text on white background. They're only readable in mouse-over-state, where the background redraws blue.

For the dark-theme, there are more display-problems to consider, I'll post them in separate issues.
codebase: grommunio-web-3.15-72-g08d9cc51d