Houdini gradient border animation

houdini-gradient-border-animation.markdown

Houdini gradient border animation

Chromium browsers only

A Pen by Michelle Barker on CodePen.

License.

index.html

<div class="wrapper">
	<div class="box">
		<p>Conic gradient</p>
	</div>

	<div class="box">
		<p>Radial gradient</p>
	</div>
</div>

style.css

@import url("https://fonts.googleapis.com/css?family=Raleway:400");

* {
	box-sizing: border-box;
}

@property --angle {
  syntax: '<angle>';
  initial-value: 90deg;
  inherits: true;
}

@property --gradX {
  syntax: '<percentage>';
  initial-value: 50%;
  inherits: true;
}

@property --gradY {
  syntax: '<percentage>';
  initial-value: 0%;
  inherits: true;
}

body {
	font-family: Raleway, sans-serif;
	text-align: center;
	margin: 0;
	padding: 1rem;
	background-color: rgba(10, 12, 18, 1);
	color: white;
	min-height: 100vh;
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	justify-content: center;
}

p {
	margin: 0;
}

:root {
	--d: 2500ms;
	--angle: 90deg;
	--gradX: 100%;
	--gradY: 50%;
	--c1: rgba(168, 239, 255, 1);
	--c2: rgba(168, 239, 255, 0.1);
}

.wrapper {
	min-width: min(40rem, 100%);
}

.box {
	font-size: 3vw;
	margin: max(1rem, 3vw);
	border: 0.35rem solid;
	padding: 3vw;
	border-image: conic-gradient(from var(--angle), var(--c2), var(--c1) 0.1turn, var(--c1) 0.15turn, var(--c2) 0.25turn) 30;
	animation: borderRotate var(--d) linear infinite forwards;
}

.box:nth-child(2) {
	border-image: radial-gradient(ellipse at var(--gradX) var(--gradY), var(--c1), var(--c1) 10%, var(--c2) 40%) 30;
	animation: borderRadial var(--d) linear infinite forwards;
}

@keyframes borderRotate {
	100% {
		--angle: 420deg;
	}
}

@keyframes borderRadial {
	20% {
		--gradX: 100%;
		--gradY: 50%;
	}
	40% {
		--gradX: 100%;
		--gradY: 100%;
	}
	60% {
		--gradX: 50%;
		--gradY: 100%;
	}
	80% {
		--gradX: 0%;
		--gradY: 50%;
	}
	100% {
		--gradX: 50%;
		--gradY: 0%;
	}
}