Here’s my mainpage layout:
<HTML>
<HEAD>
</HEAD>
<FRAMESET>
<FRAMESET>
<FRAME name="menu" src=<%=menu%> >
<FRAME src=<%=bottom%> >
</FRAMESET>
<FRAMESET>
<FRAME src=<%=tittle%> >
<FRAME name="center" src=<%=center%>>
</FRAMESET>
</FRAMESET>
Since this page was build 10 years ago and html5 does not support framesets anymore I’d like to modernize my layout.
Which would be the alternative nowadays?
There isn’t a alternative per se. “Just” rewrite your whole page using modern HTML&CSS. If you have no idea on how to do that I would suggest getting a book or two (on HTML5&CSS3) and work your way from there. Sorry but there really isn’t anything more specific we can answer you here.