seedling problem

Im new my first grow. and im working from my phone. So i have 3 day old seedlings tallest one is almost 3 inches and one of the leaves has a hint of yellowing on the inside

Is it the bottom leaf?
Is it shaped more 'teardrop' than the leaves higher up the stem??

do not feed seedlings ferts check temps and humidity if its its first leaves they will yellow and fall off

I havent fertilized them. Im sorry im new and the seedling only has the first leaves on it. The yellowing is on the top inside of the "rugged" leaves

You didn't really give a lot of info but throwing this out there: watering too much can cause them to yellow as well and is a common beginner mistake. But post a picture and give all the details of care and someone can get you pointed in the right direction I'm sure.

I dont quite know how to add a picture on here with my phone.