[class*="col-"] {
    float: left;
    width: 100%;
} 
.col-1 {width: 8.33%;}
.col-2 {width: 16.66%;}
.col-3 {width: 25%;}
.col-4 {width: 33.33%;}
.col-5 {width: 41.66%;}
.col-6 {width: 50%;}
.col-7 {width: 58.33%;}
.col-8 {width: 66.66%;}
.col-9 {width: 75%;}
.col-10 {width: 83.33%;}
.col-11 {width: 91.66%;}
.col-12 {width: 100%;}

@media only screen and (max-width: 600px) {
    [class*="col-"] {
    width: 100%;
    }
    .header {
        height: 200px;
        margin: 0;
        position: absolute;
        top: 1px;
        left: 1px;
        right: 1px;
        background-color: orange; 
        text-align: center; 
        color: white;
    }
    h1 {
        padding-top: 2.6rem;
    }                
    #menu {
        background-color: red;
        border-bottom: 4px solid yellow;   
        width: 100%;
        position: absolute;
        top: 12.5rem;
        left: 1px;
        right: 1px; 
        text-align: center;
    }
    #menuhome {
        padding-top: 0.8rem;
    }
    #menuoverons {
        padding-top: 1.2rem;
    }
    #menutarieven {
        padding-top: 1.2rem;
        padding-bottom: 1.2rem;
    }
    #menucontact {
        padding-bottom: 0.8rem;
    }
    a {
        text-decoration: none;
        color: white; 
        display: block;
    }
    #left {
        position: relative;
        top: 20.8rem;
        margin: 0;
        padding-bottom: 1.5rem;
        background-color: lightgoldenrodyellow; 
        color: black;
    }
    .left {
        padding-top: 2rem;
    }
    #saxofoon {
        padding-left: 1.9rem;
        height: auto;
        width: 22.5rem;
        max-width: 100%;
        max-height: 100%;
    }
    #right {
        position: relative;
        top: 21rem;
        padding-left: 1rem;
        padding-right: 1rem;
    }
    .trompetsaxofoon {
        width: 30%;
        height: 25%;
        padding: 1.4rem 0rem 1.4rem 1rem;
    }
    .footer {
        position: absolute; 
        bottom: 0;
        left: 0;
        right: 0; 
        top: 154rem;
    }
    footer {
        padding-top: 2rem;
        padding-bottom: 2rem;
        font-weight: bold;
        text-align: center;
        background-color: red; 
        color: black;
    }  
    }

@media only screen and (min-width: 600px) {
.header {
    height: 200px;
    margin: 0;
    position: absolute;
    top: 0rem;
    left: 0rem;
    right: 0rem;
    background-color: orange; 
    text-align: center; 
    color: white;
}
h1 {
    padding-top: 2.6rem;
}
#menu {
    background-color: red;
    position: absolute;
    top: 12.5rem;
    left: 0rem;
    right: 0rem;  
    border-bottom: 4px solid yellow;  
    height: 2.3rem;      
}
a {
    padding-top: 1rem;
    padding-bottom: 1rem;
    text-decoration: none;
    color: white;  
    margin: 0rem 1.2rem;
    position: relative;
    top: 0.5rem;
}
#left {
    position: relative;
    top: 14.5rem;
    right: 1rem;
    padding: 1rem 1rem 28rem 1rem;
    background-color: lightgoldenrodyellow; 
    color: black;
}
#saxofoon {
    padding-left: 0.7rem;
    height: auto;
    width: 19.7rem;
    max-width: 100%;
    max-height: 100%;
}
#right {
    position: relative;
    top: 15.4rem;  
    padding-left: 1.5rem;
}
.trompetsaxofoon {
    width: 19rem;
    max-width: 100%;
    max-height: 100%;
    padding: 0.7rem 0.5rem;
}
img {
    padding-left: 1.1rem;
}
.footer {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    top: 80rem;
}
footer {
    padding-top: 2rem;
    padding-bottom: 2rem;
    font-weight: bold;
    text-align: center;
    background-color: red; 
    color: black;
}  
}