Here are my other changes, in addition to changing the tabs to space:
1) div,plotwrapper: I changed the width to 73% from 75% (so i can add the separator), I removed the background color and added in margin 0.
2) #plottoggle: I changed the width to 73% from 75% (so i can add the separator), margin 0 added, overflow hidden added, float left added
3) I added in div.separator section
4) div#menu: position relative removed, z-index 2 removed, padding-bottom removed, float changed to left, padding 0 and margin 0 added, overflow hidden added, width adjust to 26% from 25%
5) div#menutabs: width removed, float removed, height adjusted to 100% from 98%