my 1990 mazda Miata keeps on blowing fuses when I turn the lights on but its just the headlights

You may have short,check wire,s at head light,s and tail light,s,side marker light,s all so,if no short is found may need to check your light swicth it self.

That was the proper answer, you may have a break in a connector or wires that have been rubbing together until all the shield has been rubbed off. This would cause the condition in the headlights only. My two cents worth.

199e Miata LE had Same symptoms as 15A and 20A “Tail” fuse blown — taillights, console lights, and halo lights of custom lights (Jeep style LED) not working. Regular headlights worked fine. We found root cause of problem to be the wires and cables going the custom front headlights to be crushed and severed when closing the pop-up light lids. We repaired the broken wires by splicing and wrapping black electrical tape around them. Then we tie wrapped the wire harnesses away from the stabilizer bar which the harness got stuck under upon closing the light lids.