Tab Color not the same

Thanks for filing an issue! Please answer the questions below so I can help you.

• iTerm2 version:Build 3.1.5.beta.2
• OS version:10.13.1 (high sierra)

Detailed steps to reproduce the problem: 1.set the tab color to RGB 38,38,38 2.set the color of background to RGB 38,38,38

What happened: Tab color and background color are not the same, tab color should be more grey but it looks like black.

What should have happened: Background color should be same, but they are not see the image below.