Brake Fluid on the Ground Options

[asalamay]

On have a 97 celica St, about a month ago my brake would flicker on and off when going around a bend. I checked my brake fluid and it was a little low, so I refilled it and it cured the problem. Didn't think anything of it, since I had not checked the brake fluid in quite some time. Then the other day I noticed some fluid on the garage floor and it felt like brake fluid, but not really sure. I have been keeping an eye on the fluid level and I did have to put in a very tiny bit, but wasn't sure if I filled it up all the way from before. I have had someone push the brake pedal and look for the leak, but can't see it. But when I come out in the morning sometimes there is about a dime size puddle directly under the drivers side seat. Not by the wheels or by the master cylinder. Which was kind of confusing, but I looked under the car and noticed there is a black plastic cover of some type that runs under the car. It appears to be a cover of some type and it does have fluid all over it. Does this cover the brake lines as they run to the back of the car? Also does anyone have a detailed diagram of the brake system that shows how the brakes line run through out the car?