Simplify the following text for a Grade 10 native English-speaking person.
Original: Third , for some color blind people , color can only be distinguished if there is a sufficient `` mass '' of color : thin lines might appear black while a thicker line of the same color can be perceived as having color .
Simplified: Thirdly , for some color blind people , color can only be distinguish if there is enough color : thin lines might appear black , but a thicker line of the same color can be seen in the correct color .