Styling is off on file-error box in Data Lib + close button

[knutole]

• [x] fix offset when hovering
• [x] fix font-color on hover
• [x] add "Close" button to remove error box. (currently it's removed on click anywhere on box.)

[knutole]

see also https://github.com/systemapic/wu/issues/350

[knutole]

• [ ] overflow on horisontal, shouldn't be possible to scroll sideways

[knutole]

@jorgenevil you have any suggestions here?