In Google Chrome, you can enable or disable an experimental flag called Single-tab mode.
When enabled, active Chrome windows with only a single tab open receive a special, minimal visual treatment of having no color on the tab bar and borders making them plain white.
When disabled (default), Chrome windows with only a single tab open will show color on the tab bar and borders. In Windows 10, the Chrome tab bar and borders color will be the same accent color you selected in Windows 10 if you turned on show colors on Title bars and windows borders. Otherwise, the color will be gray by default.
This tutorial will show you how to enable or disable single-tab mode for a minimal visual treatment in Google Chrome for your account in Windows 7, Windows 8, or Windows 10.