Fitting shower in bathroom

[mikeinglasgow]

I have just had a shower fitted over the bath. The wall was only part-tiled so I fitted some coloured perspex sheeting above the tiles to save having to retile the whole room. Problem now is that the sheeting is not as thick as the tiles below so I don't have a straight edge to fit the shower screen to. Any suggestions on what I can use to fill the gap between perspex sheeting and the screen fitting?

 

[foxhole]

Take screen off and refit level with tiles, should have used perspex to same depth as tiles, though not ideal as will scratch and if not sealed all round will grow mold beneath.