#tabs {
    display: block;
    float: left;
    width: 100%;
}

a.tab { 
    border-collapse: collapse; 
    border-style: solid solid none solid;  
    border-color: royalblue; /* updated border color */
    border-width: 1px 1px 0px 1px; 
    font-family: arial; 
    text-decoration: none;
    width: 11%;
    text-align: center;
    float: left;
    color: royalblue; /* updated font color */
}

a.tab:hover { 
    border-color: royalblue; /* updated hover border */
    background-color: #3D9ACC; 
    text-decoration: none;
    color: royalblue; /* updated hover font color */
}

.panel { 
    border: solid 1px royalblue; /* updated panel border */
    background-color: black; 
    padding: 5px; 
    overflow: auto; 
    clear: left; 
}