This is not a :focus selector, which will highlight when you focus on an element. But a selector to fire when something within is focused.
In our case, we’ll be focusing on forms (I see what you did there 😏)
The end result will look like this:
HTML Structure
As for our HTML, we wil create a form with 2 inputs.
<form>
<label for="username">Username</label>
<input type="text" name="username" />
<br /><br />
<label for="password">Password</label>
<input type="password" name="username" />
</form>
That’s all we need for this specific demo.
CSS focus-within pseudo selector
The :focus-within is a pseudo-selector, like :before or :after.
Let’s first add some basic styling.
body {
display: flex;
min-height: 100vh;
justify-content: center;
align-items: center;
}
form {
border: 1px dashed #333;
padding: 25px;
}
This will make sure our form is absolutely centered on the page and has a small border to showcase our effect later on.
Now we want to draw the users attention to the form, but making it a fancy colour when they focus an input field.
form {
border: 1px dashed #333;
padding: 25px;
transition: background 0.3s ease;
}
form:focus-within {
background: #f4d35e;
}
This will change the background of our form to yellow.
You can see this in this Codepen.
See the Pen Why CSS :focus-within is amazing by Chris Bongers (@rebelchris) on CodePen.
Making it more awesome
Yes, we can even make it more awesome by using a box-shadow hack we can create a kind of modal effect!
form {
border: 1px dashed #333;
padding: 25px;
transition: all 0.3s ease;
box-shadow: 0 0 0 100vmax rgba(0, 0, 0, 0);
}
form:focus-within {
background: #f4d35e;
box-shadow: 0 0 0 100vmax rgba(0, 0, 0, 0.7);
}
We create a box-shadow that is 100% of the viewport biggest position (width or height). Initially, this will be at 0 opacity.
When we have a :focus-within we change the opacity to 70%.
The effect is a lightbox-like effect ✨.
See the Pen Why CSS :focus-within is amazing ~ Modal Effect by Chris Bongers (@rebelchris) on CodePen.
Browser Support
The :focus-within selector actually has pretty good support, considering IE is dead already.
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