86 Honda Civic SI "invisible" water leak

When it rains or snows, the floor only of my 86 Civic Si hatchback ends up soaked, sometimes standing water. there is no visible leak anywhere, no water leaking in anywhere obvious. it’s just the floor, the water seems to come up from beneath the carpet. replaced windshield, didn’t work.
Any ideas out there? the car is otherwise in great shape, I bought in new in 1986.

Does the car have a sun-roof??

Is there any water IN the doors???

Is there any body rot? Often water can migrate from a psot under the cowling below the windshield and migrate through a rotted area between the wheelwell and the door, entering the cabin in the back of the kickpanel. As already alluded to, if you have a sunroof the drain channel in the A-pillar can get clogged and the water migrate in from the channel.

Someone beeds to look. You could always ask a body shop how much they’d charge just to take a look-see and tell you where the water is migrating from.

Yes, it has a sunroof. there is no water in the doors or anywhere but the floor (that I can see anyway). If it is coming in behind the kick panel, wouldn’t that keep it on the floor of the driver’s side? sometimes it’s on the passenger side, sometimes the drivers side, sometimes both. there is some rust on the body of course.
I will see if I can collect a few theories here and take them and the car to a body shop.

Most sunroofs drain through channels in the A-pillars, the pillars on the sides of the windshield. Those pillars can become clogged and the water find its way into the passenger compartment. Open your sunroof and try cleaning out the drain passages if you have them.

I had a similar problem with my '88 Accord.
Turned out to be leaking around a tail light.