For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
Add something like this to your form template custom.css:
Sorry, but I don't think this is good advice. Without seeing and inspecting the form page, it's a shot in the dark at best. Actually, a bad shot, because:
1. As indicated, it depends on the Joomla template what current CSS is. Can't explain all best CSS practices here, but depending on existing CSS the properties should be chosen accordingly and the selectors may be more refined, not least to avoid !important.
2. It's incomplete as it's neither including CSS for the "control" class, nor media queries -- again, likely depending on template CSS.
So, it won't help the OP. If anything, it may rather make things worse as he/she is obviously not entirely familiar with CSS matters.
@amitfalana, as mentioned, use your browser inspector and familiarize yourself with CSS, or hire someone to do it for you.
.fabrikGroup.form-horizontal .control-label {
width: 120px;
}
.fabrikGroup.form-horizontal .controls {
margin-left: 140px;
}