Web‑safe colors are the 216 colors used by browsers on both the Windows and Mac OS platforms. By working only with these colors, you ensure that colors in art you prepare for the web display accurately in a web browser.
You can identify web‑safe colors in the Adobe Color Picker by using either of the following methods:
Select Only Web Colors in the lower-left corner of the Color Picker, and then choose any color in the Color Picker. When this option is selected, any color you pick is web‑safe.
Choose a color in the Color Picker. If you choose a color
that isn’t web‑safe, an alert cube appears
next to the color rectangle in the upper-right area of the Color
Picker. Click the alert cube to select the closest web‑safe color.
(If no alert cube appears, the color you chose is web‑safe.)