I have a content box in photoshop with the background color #bc0018 with a 65% opacity and 50% fill.

I am able to translate the backgroundcolor and opacity part to this, but without the 50% fill the backgroundcolor looks different.

.content-box {
    background-color: rgba(188, 0, 24, 0.65); }

Any suggestions on also getting the proper "fill" in CSS?


I did just divide the opacity by half and it appears to achieve the same effect as a 50% fill. Still, I would love to hear how other people do this? I definitely don't want to create an image just for this.

.content-box {
    background-color: rgba(188, 0, 24, 0.325); }


  • I think what you want to do is set the opacity to 100% on your color in Photoshop. Screencapture and grab that actual color from the screencapture. You can then apply the color to your div and set the opacity to 65% and get the same color. Just a theory, anyways. Let me know if it helps!
    – Elliot Bonneville
    Commented Mar 17, 2012 at 19:33
  • What is the 50% against in photoshop? Simply transparent or transparent over a white background? #bc0018 at 50% over white translates to #dd7f8b. Over black it translates to #5e000c. Don't get me wrong I like RGBa values and their use, but if you can avoid them it's sometimes better for compatibility sake.
    – Scott
    Commented Mar 17, 2012 at 20:48
  • The problem I ran into using a simple hex value was that the text became transparent too. I used rbga as suggested in stackoverflow.com/questions/806000/… and css3.info/opacity_rgba_and_compromise
    – Abe
    Commented Mar 19, 2012 at 17:16
  • 1
    Ahh yeah, CSS opacity effects all children as well. That makes more sense. If you actually want transparency in the web page, then RGBa is the best bet for a background color provided you're okay with lack of support in older browsers.
    – Scott
    Commented Mar 19, 2012 at 17:24

2 Answers 2


Multiply the opacity and fill opacity fractions, and you get the final opacity value. In your case this would be 0.65*0.5 = 0.325. So you're right that halving the opacity in this case works.

However, there are certain pitfalls that make a straightforward conversion from photoshop to CSS difficult. Fill opacity in PS will not affect drop shadows and such, but CSS opacity will also affect any analogous box-shadows you apply.


rgba seems to be nothing more than regular rgb values

{ background-color:rgba(154,201,40,0.5); }

with the additional alpha/opacity value

{ background-color:rgba(154,201,40,0.5); }

So just paste the full opacity color values in the first three boxes (rgb), and set opacity for it in the last value e.g. 0.5 is 50% transparency...

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