html {
	scroll-behavior: smooth;
}

body {
	margin: 0px;
	background-image: url("../img/background.png");
	background-size: 100vw;
}

<style>
  @import url('https://fonts.googleapis.com/css2?family=Rubik:wght@500;600;700&display=swap');
  @import url('https://fonts.googleapis.com/css2?family=Sofia+Sans:wght@300&display=swap');
</style>

header{
/*	margin: 0px 100px 0px 100px;*/
}

header ul{
	background-color: #EBEBEB;
	padding: 5px;
	margin: 0px;
}

.active {
	color: #0cc446;
/*	border-bottom: 2px solid #F25C54;*/
}

main {
	font-family: 'Sofia sans', sans-serif;
	line-height: 1.5;
	background-color: white;
	margin: 0px 100px 100px 100px;
	padding: 50px;
/*	box-shadow: 0px 0px 15px grey;*/
}

.indexBild {
	width: 25vw;
	box-shadow: 0px 0px 15px grey;
	float:left;
}

.intro {
	display: grid;
	grid-template-columns:1fr 2fr; 
	align-items: start;
	column-gap: 15px;
	margin-bottom: 50px;
}

h1 {
	font-family: 'Rubik', sans-serif;
	font-weight: bold ;
	font-size: 40px;
	padding-top: 20px;
	padding-bottom: 20px;
	background-color: white;
	margin: 0;	
}

h2 {
	font-size: 25pt;
	margin: 0px;
	word-break: break-all;
	text-align: left;
}

h3 {
	font-size: 20pt;
}

h4 {
	color: #e64b43;
}

nav {
  text-align: center;
}

nav ul {
	padding-inline-start: 5px;
}

nav li {
	font-family: 'Rubik', sans-serif;
	font-size: 20px;
	text-align: center;
	display: inline;
	padding-inline: 20px;
	margin-inline: 0px;
}  

.mitte {
	border-inline:2px solid black;
}

main nav {
	padding: 0px;
	margin: 0px;
	align-items: center;
}


main nav ul {
	padding: 0px;
	margin: 0px;
	display: flex;
	flex-direction: row;
/*	flex-wrap: wrap;*/
	justify-content: space-between;
	align-items: center;
}

main nav ul li {
	padding: 0px;
}

main nav a {
	font-size: 12pt;
/*	display: inline;
	margin-inline: 0px;*/
}

.abschnitt h3 {
	margin: 0px;
}

.abschnitt {
	display: grid;
	grid-gap: 1rem;
	grid-template-columns: 1fr 2fr;
	margin: 50px 0px 125px 0px;
}

.bilder {
	display: grid;
	grid-gap: 1rem;
}

.oneColumn {
	grid-template-columns: 1fr;
}

.oneColumn img {
	max-width: 60vw;
	max-height: 40vw;
	place-self: center;
	align-content: center;
}

.twoColumns {
	grid-template-columns: 1fr 1fr;
}

.twoColumns img {
	width: 25vw;
	max-height: 25vw;
}

.threeColumns {
	grid-template-columns: 1fr 1fr 1fr;
}

.threeColumns img {
	width: 15vw;
}

.bild{
	object-fit: contain;
}

a {
	text-decoration: none;
	color: black;
}
a:hover {
	color: #F25C54;
	border-bottom: 2px solid #F25C54;
	/*transition: all 0.5s ease;*/
}

.portfolio a {
	color: orange;
	text-decoration: none;
}

.portfolio a:hover {
	color: #F25C54;
	border-bottom: 2px solid #F25C54;
}

.shadow {
	box-shadow: 0px 0px 10px lightgrey;
/*	border: 3px grey;*/
}

#more {display: none;}

button {
  border: none;
  color: white;
  padding: 15px 15px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  margin: 0px;
  cursor: pointer;
  background-color: orange;
  align-self: center;
}

button:hover {
	background-color: #F25C54;
}

footer {
	margin: 20px 0px 0px 0px;
	text-align: center;
}

.backtotop {
	display: inline-block;
	color: orange;
	padding: 10px;
	text-align: center;
	margin-top: 10px;
}

.backtotop:hover {
	background-color: #F25C54;
	color: white;
	border-bottom: none;
}

/*.ueber {
	font-family: 'Rubik', sans-serif;
	background-color: white;
	margin: 75px 350px 100px 350px;
	padding: 50px;
	max-width: 1000px;
	box-shadow: 0px 0px 15px grey;
}*/

.ueberMain {
	margin: 0px 25% 100px 25%;
}

.ueber ul {
	margin: 0;
}

.ueber ul li {
	font-size: 12pt;
	line-height: 15pt;
	margin-bottom: 5px;
}

.ueber h3 {
	margin: 20px 0px 10px 0px;
}

.ueber h4 {
	margin: 20px 0px 10px 0px;
}

.download {
	color: orange;
}

iframe {
	margin: auto;
}