@media screen and (min-width:551px){
    /*551px以上*/
.s_bo1 {
    position: relative;
    color: black;
    background: #3cccf8;
    line-height: 1.7;
    width: 510px;
    margin: 20px 0px;
    padding: 10px;
    border-radius: 0 5px 5px 5px;
  }

.s_bo1 p{
    margin: 5px;
    padding: 3px;
}

.s_bo1:after {
    /*タブ*/
    position: absolute;
    font-family: "Font Awesome 5 Free",'Quicksand','Avenir','Arial',sans-serif;
    content: ' ニュース';
    background: #2196F3;
    color: #fff;
    left: 0px;
    bottom: 100%;
    border-radius: 5px 5px 0 0;
    padding: 3px 7px 3px;
    font-size: 0.7em;
    line-height: 1;
    letter-spacing: 2px
}}

@media screen and (max-width:550px){
    /*550px以下*/
.s_bo1 {
    position: relative;
    color: black;
    background: #3cccf8;
    line-height: 1.7;
    width: 100%;
    margin: 20px 0px;
    padding: 10px;
    border-radius: 0 5px 5px 5px;
    }
.s_bo1 p{
    margin: 5px;
    padding: 3px;
}

.s_bo1:after {
    /*タブ*/
    position: absolute;
    font-family: "Font Awesome 5 Free",'Quicksand','Avenir','Arial',sans-serif;
    content: ' ニュース';
    background: #2196F3;
    color: #fff;
    left: 0px;
    bottom: 100%;
    border-radius: 5px 5px 0 0;
    padding: 3px 7px 3px;
    font-size: 0.7em;
    line-height: 1;
    letter-spacing: 2px
}}