In the fields below the last value is between 0.0 for fully transparent, and 1.0 for fully opaque. The second Red row shows fully opaque, the rest are partially transparent.
Red : background-color:rgba(255,0,0,0.3)
Red : background-color:rgba(255,0,0,1.0)
Green : background-color:rgba(0,255,0,0.3)
Blue : background-color:rgba(0,0,255,0.3)
Grey : -color:rgba(192,192,192,0.3)
Yellow : background-color:rgba(255,255,0,0.3)
Cerise : background-color:rgba(255,0,255,0.3)
Part transparent Red text : color:rgba(255,0,0,0.3)
The code is:
<p style="background-color:rgba(255,0,0,0.3);">Red : background-color:rgba(255,0,0,0.3)</p>
<p style="background-color:rgba(255,0,0,1.0);">Red : background-color:rgba(255,0,0,1.0)</p>
<p style="background-color:rgba(0,255,0,0.3);">Green : background-color:rgba(0,255,0,0.3)</p>
<p style="background-color:rgba(0,0,255,0.3);">Blue : background-color:rgba(0,0,255,0.3)</p>
<p style="background-color:rgba(192,192,192,0.3);">Grey : -color:rgba(192,192,192,0.3)</p>
<p style="background-color:rgba(255,255,0,0.3);">Yellow : background-color:rgba(255,255,0,0.3)</p>
<p style="background-color:rgba(255,0,255,0.3);">Cerise : background-color:rgba(255,0,255,0.3)</p>
<p style="color:rgba(255,0,0,0.3);">Part transparent Red text : color:rgba(255,0,0,0.3)</p>