Akhil Arjun

Posted on Aug 3, 2020

One line - Dark Mode using CSS

#beginners #css #webdev #tutorial

This is an absolute no-brainer method of converting an already developed website to support dark mode.

Without further ado let's get into it! 👾

Consider this news application for example

Now add the magic CSS



html[theme='dark-mode'] {
    filter: invert(1) hue-rotate(180deg);
}

Voila! you are done ✌

Dark mode achieved

Explanation

Now let's try and understand what is going on under the hood.

The filter CSS property applies graphical effects like blur or color shift to an element. Filters are commonly used to adjust the rendering of images, backgrounds, and borders. (Reference: MDN Web Docs)

For this dark mode, we would be using two filters namely invert and hue-rotate

invert filter helps to invert the color scheme of the application. So, black becomes white and white becomes black and similarly for all the colors.

hue-rotate filter helps us with all the other colors that are not black and white. Rotating Hue by 180 degrees, we make sure the color theme of the application does not change but just attenuate the colors of it.

The only catch with this method is, it will also invert all the images in your application. So we will add the same rule to all images to reverse the effect.



html[theme='dark-mode'] img{
    filter: invert(1) hue-rotate(180deg);
}

and we will also add a transition to the HTML element to make sure the transition does not become flashy!



html {
    transition: color 300ms, background-color 300ms;
}

Result:

There we have our Dark mode implemented. Great job guys!

My days are fueled with coffees and only coffees. So I know, you know what we all should do 🤞

Top comments (52)

Sodeeq Olamide • Aug 3 '20

This is very amazing, I'm surprised to realize to know that achieving dark mode on one's site is simpler than I thought

Akhil Arjun • Aug 3 '20

Well, they say a magician should never reveal his tricks. Maybe I am just a bad one 😂😀

technikhil314 • Aug 3 '20

if you want full greyscale dark mode then use invert(1) greyscalle(1)

Akhil Arjun • Aug 3 '20

Yes, but the only downside to it is that even the images go greyscale

Gavin Sykes • Aug 3 '20

Would that be such a bad thing? I've always thought having them do that would be pretty cool.

Akhil Arjun • Aug 3 '20

Oh! yes, it would be. I once worked for a client where the dark mode had everything greyscaled. It was awesome 😎 It's just that not every UX would work better that way. So it has to be informed decision

technikhil314 • Aug 3 '20

Yeah agreed.

Louis Low • Aug 22 '20 • Edited

Excellent! Changing themes also can be made with Yogurt Framework based on a web browser or app settings. Read Theme Auto.

<html theme="auto">
  ...
    <!-- e.g. To compensate inverted image -->
    <img theme="auto">
    <!-- e.g. To compensate other inverted elements -->
    <y theme="auto"></y>
    <span theme="auto"></span>
  ...
</html>

And to force the page theme to turn into either dark or light.

<html theme="invert">
  ...
    <!-- e.g. To compensate inverted image -->
    <img theme="invert">
    <!-- e.g. To compensate other inverted elements -->
    <y theme="invert"></y>
    <span theme="invert"></span>
  ...
</html>

Dimas • Aug 4 '20

Hello!
That is amazing simple decision!
Great! Thank you very much.
But it is also converted all my background images...
Is it exist any option for filter them?

Akhil Arjun • Aug 4 '20

Yeah. You have to apply invert filter again on images to re-colorize them and turn back the hue a whole of 180deg.
We can do that by selecting all images so

html[theme='dark-mode'] img{
    filter: invert(1) hue-rotate(180deg);
}

Paul Phillips • Aug 4 '20

I think he was referring to CSS background-image not img's

Akhil Arjun • Aug 4 '20

I get it. Well, there are a couple of ways we can achieve that too. If it is just a div with a background-image set. Then applying filter would not be a problem there, but if that element has some content then the filter might affect it all too. So we might have to check for specialized solutions.
There is a beautiful article on css-tricks regarding the same css-tricks.com/apply-a-filter-to-a....

Hope that helps 😀

Dimas • Aug 4 '20

Yes, correct.
I found only the way to add extra "non-dark-mode" class to turn them back...

Jáder Carvalho de Medeiros • Aug 3 '20

Excellent! Could you please share the JavaScript code to toggle between themes as well?

Akhil Arjun • Aug 3 '20

Please check out the post-

Dark Mode - Unmistified! 🐱‍👤

Akhil Arjun ・ Aug 3 ・ 3 min read

#beginners #css #tutorial #webdev

Akhil Arjun • Aug 3 '20

I am writing a post for the javascript side of it too. Will post it today itself 🙂

jojobyte • Oct 10 '20 • Edited

Someone likely mentioned this already, but there seems to be a "gotcha" with Firefox and Edge.

Firefox appears to not apply the filter to the background-color of the html or body element.

And Edge (not that I actually care) wont apply the filter to body but will to html

So these wont work

html[theme='dark-mode'] {
    filter: invert(1) hue-rotate(180deg);
}

html { background-color: #fff; } /* no luck in firefox, works in Edge */
body { background-color: #fff; } /* no luck in firefox nor in Edge */

Cross-Browser Workaround

Put all your stuff in a wrapper element just under the body.

html[theme='dark-mode'] {
    filter: invert(1) hue-rotate(180deg);
}

/* create a wrapper element and it works great */
body > .wrapper { background-color: #fff; }

Allestri • Sep 27 '20

Hey there !
I'm posting this to warn you about the general visual hierarchy of any app using this no-brainer method.
Your components should never be darker than your background, see this tweet for any references.

twitter.com/steveschoger/status/11...

While I can see some uses cases when this method is simple yet effective, it would strongly suggest anyone reading this to dive into Custom CSS properties and setting up colors scheme by hand, especially when you have a strong color identity and things can spice a little bit by naively inverting those ( accessibility and design issues ).

David Vo • Aug 4 '20

What's the performance impact of that filter on different browsers and platforms?

Akhil Arjun • Aug 5 '20

It would be a very lomg converstaion. But since we are using transition property on the html block element we can go ahead and addwill-change: transform property to it too.
This will force it into GPU rendering the page and thereby making it smooth

There is a long awesome post in Smashing Magazine for this
smashingmagazine.com/2016/12/gpu-a...

Hope this helps