check all the drain holes, their 4 that block up, the shoots are in the door openings inn the middle of the hinge, u will see it, its a little rubber shoot, stick a bit of wire up it, also open the sunroof and in each corner the water passes down (the 2 front corners go down to the front doors) so do the same here too with the bit of wire
that should sort it, if not your sunroof seal may need renewing, quire dear for what they are, around 40 notes i think (without checking)