main.css

/* RESET STYLES
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:root {
	--panel-width: calc(100% / 7);
	--darkblue: #02020c;
	--white: #fff;
	--lightgray: #fafafb;
}

* {
	padding: 0;
	margin: 0;
	box-sizing: border-box;
}

ul {
	list-style: none;
}

a {
	color: inherit;
	text-decoration: none;
}

h1 {
	font-size: 3rem;
}

body {
	height: 100vh;
	font-family: "Montserrat", sans-serif;
	color: var(--white);
	background: var(--darkblue);
	overflow: hidden;
}

/* MAIN STYLES
–––––––––––––––––––––––––––––––––––––––––––––––––– */
.page-header {
	position: fixed;
	top: 30px;
	right: 50px;
	z-index: 1;
}

.page-header ul {
	display: grid;
	grid-column-gap: 30px;
	grid-template-columns: repeat(3, 1fr);
}

.page-header ul a {
	display: inline-block;
	padding: 4px 8px;
	border: 1px solid transparent;
}

.page-header .active a {
	border-color: var(--white);
}

.panels .panel {
	position: fixed;
	top: 0;
	left: 0;
	bottom: 0;
	width: calc(var(--panel-width) + 1px);
	clip-path: inset(100% 0 0 0);
	background: var(--lightgray);
	transition: all 1s cubic-bezier(0.25, 1, 0.25, 1);
}

.panels .panel:nth-child(2) {
	left: var(--panel-width);
}
.panels .panel:nth-child(3) {
	left: calc(var(--panel-width) * 2);
}
.panels .panel:nth-child(4) {
	left: calc(var(--panel-width) * 3);
}
.panels .panel:nth-child(5) {
	left: calc(var(--panel-width) * 4);
}
.panels .panel:nth-child(6) {
	left: calc(var(--panel-width) * 5);
}
.panels .panel:nth-child(7) {
	left: calc(var(--panel-width) * 6);
}

.page-main {
	display: flex;
	height: 100%;
	padding: 100px 15px;
}

.page-main > div {
	text-align: center;
	margin: auto;
}

.page-main > div > * {
	opacity: 0;
	transition: all 0.5s ease-out;
}

.page-main h1 {
	transform: translateY(-100px);
}

.page-main p {
	font-size: 20px;
	margin-top: 20px;
	transform: translateY(100px);
}

.page-main a {
	text-decoration: underline;
}

/* ANIMATIONS ON LOAD
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.loaded .panels .panel {
	clip-path: inset(0);
	transition-delay: calc(var(--index) * 0.06s);
}

.loaded.second-round .panels .panel {
	clip-path: inset(0 0 100% 0);
}

.loaded.third-round {
	overflow: auto;
}

.loaded.third-round .page-main > div > * {
	opacity: 1;
	transform: none;
}

/* FOOTER STYLES
–––––––––––––––––––––––––––––––––––––––––––––––––– */
.page-footer {
	position: fixed;
	right: 15px;
	bottom: 20px;
	display: flex;
	align-items: center;
	font-size: 1rem;
	padding: 5px;
}

.page-footer a {
	margin-left: 4px;
}