codigo de mi tarjeta de practica

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

body {
font-family: ‘Montserrat’, sans-serif;
background-color: #dbe2ef;
}

.card {
width: 400px;
overflow: hidden;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
background: white;
border-radius: 15px;
box-shadow: 7px 13px 37px rgba(0, 0, 0, .6);
}
.fa fa-facebook {
background: #1da1f2;
}
header {
width: 100%;
height: 200px;
overflow: hidden;
position: relative;
}

header::before {
content: ‘’;
position: absolute;
border-top: 30px solid transparent;
border-left: 400px solid white;
bottom: 0;
}

header img {
width: 100%;
height: 199px;
}

section {

padding: 10px;
overflow: hidden;
text-align: center;
}

section h2 {
margin: .5em 0;
}

section p {
margin: 1em 0;
}

ul li {
list-style: none;
display: inline-block;
margin: .5em .2em;
}
#facebooks{
background: #4267B2;

}
#twitters {
background: #1da1f2;
}
#linkedins{
background: #0077b0;

}
#youtubes{
background: #f70000

}

ul li a {
text-decoration: none;
color: white;

width: 30px;
height: 30px;
line-height: 30px !important;
border-radius: 50%;
transition: all .3s ease-in-out;
}

ul li a:hover {
transform: scale(1.2);
}

footer {
width: 100%;
height: 80px;
background: #000080;
color: white;
position: relative;
}

footer::before {
content: ‘’;
position: absolute;
border-bottom: 30px solid transparent;
border-right: 400px solid white;
top: 0;
}

footer p {
padding: 30px;
}