{
  box-sizing: border-box;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  margin: 0;
}

.header {
  padding: 10px;
  text-align: left;
  background: #10b7e4;
  color: white;
}

.header h1 {
  font-size: 40px;
}

.navbar {
  overflow: hidden;
  background-color: #333;
  position: sticky;
  position: -webkit-sticky;
  top: 0;
}

.navbar a {
  float: left;
  display: block;
  color: white;
  text-align: center;
  padding: 14px 20px;
  text-decoration: none;
}

.navbar a.right {
  float: right;
}

.navbar a:hover {
  background-color: #ddd;
  color: black;
}

.navbar a.active {
  background-color: #666;
  color: white;
}

.dropdown {
  float: left;
  overflow: hidden;
}


.dropdown .dropbtn {
  font-size: 16px;
  border: none;
  outline: none;
  color: white;
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit; 
  margin: 0; 
}

.navbar a:hover, .dropdown:hover .dropbtn {
  background-color: red;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
}

.dropdown-content a {
  float: none;
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}

.dropdown-content a:hover {
  background-color: #ddd;
}

.dropdown:hover .dropdown-content {
  display: block;
}

.row {  
  display: -ms-flexbox; 
  display: flex;
  -ms-flex-wrap: wrap; 
  flex-wrap: wrap;
}

.side {
  -ms-flex: 30%; 
  flex: 30%;
  background-color: #f1f1f1;
  padding: 20px;
}

.main {   
  -ms-flex: 70%; 
  flex: 70%;
  background-color: white;
  padding: 20px;
}

/* Footer */
.footer {
  padding: 20px;
  text-align: center;
  background: #ddd;
}

@media screen and (max-width: 700px) {
  .row {   
    flex-direction: column;
  }
}

@media screen and (max-width: 400px) {
  .navbar a {
    float: none;
    width: 100%;
  }
}