update: if you add width in default button the bottom that takes you to the top page gets wider as well, so I just added 176px to the Button call to action and it seems to work better and is still aligned to the side bar.
ok I found this in ACP > Appearance > Styles> Bolt v3 - Style Properties
found:
Button call to action
Extra Free Forum CSS/LESS Code
now it seems to align perfectly to the side bar at 320px
OK I notice your design mode when selected shows you where things are around the forum - NICE FEATURE

Thanks
Spiro