Fix some sass lint errors in error-panel.scss
Fix some sass lint errors in error-panel.scss

fzzzy/pageshot,mozilla-services/screenshots,mozilla-services/screenshots,mozilla-services/screenshots,fzzzy/pageshot,mozilla-services/pageshot,fzzzy/pageshot,mozilla-services/pageshot,mozilla-services/pageshot,fzzzy/pageshot,mozilla-services/screenshots,mozilla-services/pageshot