.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: 200px; 
    height: calc(100vh); 
    background: teal; 
    overflow-y: auto; 
}


.main-content {
    margin-left: 200px; 
    min-height: 100vh;
    background-color: #000;
}

.sidebar a {
    display: block;
    margin: 10px 0;
    padding: 8px 12px;
    text-align: center;
    text-decoration: none;
    font-weight: bold;
    
    
    color: #000;
    background-color: #cccccc; 
    border-top: 2px solid #ffffff;    
    border-left: 2px solid #ffffff;   
    border-right: 2px solid #555555;  
    border-bottom: 2px solid #555555; 
}

.sidebar a:active {
    text-align: center;
    border-top: 2px solid #555555;
    border-left: 2px solid #555555;
    border-right: 2px solid #ffffff;
    border-bottom: 2px solid #ffffff;
    background-color: #bbbbbb;
}