/*CSS reset settings here*/
*{
    margin: 0px;
    padding: 0px;
   }
   #wrapper{
    width: 950px;
    background-color: silver;
    margin: 0 auto;
    padding: 10px;
   }
   #header{
    min-height: 150px;
    background-color: green;
    margin-bottom: 10px;
   }
   #navigation{
    min-height: 300px;
    width: 200px;
    background-color: blue;
    display: inline-block;
    vertical-align: top;
   }
   #main_content{
    min-height: 400px;
    width: 735px;
    background-color: red;
    display: inline-block;
    vertical-align: top;


   }
   .subcontents{
    min-height: 200px;
    width: 210px;
    background-color: yellow;
    display: inline-block;
    margin-top: 10px;
    margin-left: 10px;
    margin-bottom: 10px;
   }
   #advertisement{
    min-height: 120px;
    width: 660px;
    background-color: purple;
    display: inline-block;
    margin: 10px;
   }
   @media only screen and (max-width: 480px){
    #header{
        width: 35%;
        height: auto;
    }
    #navigation{
        display: none;
    }
    #main_content{
        width: 35%;
        height: auto;
    }
    .subcontents{
        width: 93%;
        height: auto;
    }
    #advertisement{
        width: 93%;
        height: auto;
    }
}
@media only screen and (min-width: 481px){
    #header{
        width: 60%;
        height: auto;
    }
    #navigation{
        display: none;
    }
    #main_content{
        width: 60%;
        height: auto;
    }
    .subcontents{
        width: 47%;
    }
    #advertisement{
        width: 95%;
    }
}
@media only screen and (min-width: 1024px){
    #header{
        width: auto;
    }
    #navigation{
        display: inline-block;
    }
    #main_content{
        width: 75%;
        height: auto;
        margin-left: 33px;
    }
    .subcontents{
        width: 30%;
    }
    #advertisement{
        width: 94%;
    }
}