Example CSS

body {
    font-family: sans-serif;
    background-color: pink;
    margin: 0px;
}
.section {
    padding: 10px;
}
  .section .inner {
    width: 50%;
    margin-right: auto;
    margin-left: auto;
    background-color: red; 
  }

#navbar {
  height: 23px;
  border-bottom: 2px solid #ce4dd6; }
  #navbar ul {
    list-style-type: none;
    margin: 0px; }
  #navbar li {
    float: left;
    width: 16.66667%;
    background-color: #e5a0e9;
    text-align: center; }
    #navbar li:hover {
      background-color: #d976e0; }
    #navbar li a {
      font-weight: bold; }
      #navbar li a:hover {
        color: #33ccff; }

section.section:first-child {
   background-color: green;
}

section.section:nth-child(2) {
    background-color: yellow;
}

section.section:nth-child(4) {
    background-color: blue;
}

#footer {
    height: 40px;
}

#footer p:first-child {
    float: left;
}

#footer p {
    float: right;
}