Fixing Sarah's css

style.css

html {
  font-family: helvetica, arial, sans-serif;
  font-size: 22px;
  color: seashell;
  background-color: black;
  opacity: 0.9;
}

header {
  position: fixed;
  height: 69px;
  width: 100%;
  border-bottom: 1px solid seashell;
  display: block;
  top: 0;
  left: 0;
  background-color: black;
}

.logo {
 height: 50px;
 padding-left: 10px;
 margin-top: 10px;
 float: left;
 display: inline-block;
}

nav li {
  display: inline-block;
  float: right;
  margin-right: 10px;
}

li {
  padding: 0 10px;
  text-decoration: underline;
}

body {
  margin-top: 70px;
  width: 2000px;
  display: flex;
  flex-direction: column;
  align-content: center;
}

.mission {
  display: flex;
  height: 700px;
  width: 1200px;
  justify-content: center;
  align-items: center;
  background-image: url("./resources/img-mission-background.jpg");
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
  text-align: center;
}

.featured {
  height: 700px;
  width: 1200px;
  justify-content: center;
  align-items: center;
  text-align: center;
}

#missionHeader {
  background-color: black;
  height: 23%;
  width: 100%;
}

#featureHeader {
  text-align: center;
  width: 100%;
}

.menu {
  width: 1000px;
  display: inline-flex;
  flex-flow: row wrap;
  justify-content: center;
}

.menu img {
  width: 300px;
  height: 200px;
  margin: 10px;
}

.menu h4 {
  text-align: center;
  margin: 0 0 20px 0;
}