HEXA

In HTMLHypertext Markup Language (HTML) is the standard markup language for creating web pages and web applications. With Cascading Style Sheets (CSS) and JavaScript, it forms a triad of cornerstone technologies... More, a color can be specified using a hexadecimal value with an alpha channel – which specifies the opacity for a color in the form: #rrggbba

Where rr (red), gg (green) and bb (blue) are hexadecimal values between 00 and ff (same as decimal 0-255).

The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (not transparent at all).