body {
    font-family: 'San Francisco', Arial, sans-serif;
    background-color: #f8f8f8;
    margin: 0;
    padding: 0;
}
header {
    background-color: #f8f8f8;
    color: #000000;
    text-align: center;
    padding: 20px;
}
nav ul{
    list-style-type: none;
    margin: 0;
    padding: 0;
    text-align: center;
}
nav li {
    display: inline;
    margin: 0 10px;
}
nav a {
    text-decoration: none;
    color: #333;
}
main {
    padding: 20px;
}
section {
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 5px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 0 5px rgba(0,0,0,0.1);
}
footer {
    text-align: center;
    background-color: #333;
    color: #fff;
    padding: 10px;
}


nav a:hover {
    color: #555;
}

.column1 {
    float: left;
    width: 50%;
  }

.column2 {
   float: right;
   width: 50%;
 }
  
  
  .row:after {
    content: "";
    display: table;
    clear: both;
  }