In this tutorial, I'll walk you through creating an animated gradient border effect using CSS custom properties, which can add a dynamic and eye-catching look to your UI components. By the end, you'll have a simple card with an animated gradient border, using css custom @property.
If you are are not familiar with css custom @property read this blog first.
Basic card structure
We will be using react for this tutorial, the basic card will look like this
import "./styles.css"; const CardAnimatedBorder = () => { return ( <div className="container"> <div className="card">This is a card with animated gradient border</div> </div> ); }; export default CardAnimatedBorder;
Adding basic styles to the card
.container { width: 100%; height: 200px; display: flex; align-items: center; justify-content: center; } .card { margin: 0 auto; padding: 2em; width: 300px; background: #1c1f2b; text-align: center; border-radius: 10px; color: #ffffff; position: relative; }
Creating a simple border
Before creating a gradient animated border let's see how to create a simple border. We will not use the css border property but instead use pseudo elements ::before and ::after for the card. Another important property here is inset which allows us to place the pseudo elements inside the card. The z-index will be -1 as we want the border to be below the card content.
.card::after, .card::before { content: ""; position: absolute; background: red; inset: -4px; z-index: -1; border-radius: 10px; }
Our card now looks like this
Adding custom property --angle
We will add a custom property to track the angle of the gradient. We will be using conic-gradient.
Add a custom property like this
@property --angle { syntax: "<angle>"; initial-value: 0deg; inherits: false; }
and make the following changes to the css
- Replace background with background-image to display gradient.
- Add an animation spin for the custom property angle.
- The conic-gradient has angle as first argument and we will be changing it in order to animate.
- Add blur and opacity for a glowing effect.
Your css should look like this
.container { width: 100%; height: 200px; display: flex; align-items: center; justify-content: center; } .card { margin: 0 auto; padding: 2em; width: 300px; background: #1c1f2b; text-align: center; border-radius: 10px; color: #ffffff; position: relative; } @property --angle { syntax: "<angle>"; initial-value: 0deg; inherits: false; } .card::after, .card::before { content: ""; position: absolute; background-image: conic-gradient( from var(--angle), transparent 70%, blue, red ); inset: -4px; z-index: -1; border-radius: 10px; animation: 2s spin linear infinite; } .card::before { filter: blur(1rem); opacity: 0.7; } @keyframes spin { from { --angle: 0deg; } to { --angle: 360deg; } }
And finally we have a card with animated gradient border.
Demo
Click here
Read more
- MDN docs @property
Original post
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