body {
  font-family: Arial;
  color: #333;
  padding-top: 200px;
}

header {
  background: rgba(217, 217, 217, 0.9);
  width: 100%;
  position: fixed;
  top: 0;
  height: 160px;
}

header h1 {
  text-align: center;
}

p {
  line-height: 1.5em;
}

img {
  display: block;
  max-width: 100%;
}

section {
  width: 95%;
  margin: 0 auto 150px auto;
  padding: 25px;
  box-shadow: 0px 0px 8px 1px rgba(0, 0, 0, 0.75);
}

/*************** Navigation Styles ***************/
header nav {
  width: 95%;
  margin: auto;
}

header nav ul {
  display: flex;
  list-style-type: none;
  margin: 0;
  padding: 0;
}

header nav ul li {
  width: 20%;
  box-sizing: border-box;
  border-left: 2px solid #666;
}

header nav ul li:first-of-type {
  border-left: none;
}

header nav ul li a {
  text-decoration: none;
  display: block;
  color: #fff;
  text-transform: uppercase;
  font-weight: bold;
  padding: 10px;
  background: #9c9c9c;
  white-space: nowrap;
  overflow: hidden;
  text-align: center;
  text-overflow: ellipsis;
}

.selected {
  background: rgba(254, 0, 187, 1);
  transition: all 1s;
}

@media only screen and (min-width: 700px) {
  /*************** Frist Section Styles ***************/
  #first article {
    display: flex;
    align-items: flex-start;
  }

  #first article img {
    margin-left: 25px;
  }

  /*************** Second Section Styles ***************/
  #second div,
  #fifth div {
    display: flex;
    justify-content: space-between;
  }

  #second article {
    width: 30%;
  }

  /*************** Third Section Styles ***************/
  #third article {
    display: flex;
    align-items: flex-start;
  }

  #third article img {
    margin-right: 25px;
  }

  /*************** Fifth Section Styles ***************/
  #fifth article {
    width: 47%;
  }

  #fifth {
    margin-bottom: 500px;
  }
}

@media only screen and (min-width: 1000px) {
  section,
  header nav {
    width: 960px;
  }
}