body {
    display: flex;            
    text-align: center;       
    justify-content: center; 
    background-color: #e7e7e7; 
    font: normal 100% Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;}   

h1 {font-size: 1.6em;}  

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;} 

.column {
    width: 100%;
    float: left;
    padding: 10px;}  

@media screen and (max-width: 720px) {
    .container {
        width: 90% !important;
        padding: 10px !important;}
    .column {width: 100%;}}

.window-header a {
    flex: 1;                
    text-align: center;     
    text-decoration: none;  
    color: #ffffff;            
    padding: 8px 12px;      
    font-size: 14px;
    border-radius: 6px;     
    margin: 0 8px;          
    background-color: #000000; 
    transition: background-color 0.2s;}