会話の吹き出し（CSS）

.entry-content .person-right,
.entry-content .person-left{
    padding-top: 15px;
    padding-bottom: 15px;
    min-height: 100px;
}
.entry-content .person-right img,
.entry-content .person-left img{
    background-color: #333;
    border: 1px solid #555;
    border-radius: 2.5em;
    width: 75px;
    height: 75px;
    margin-top: 2px;
    background-size: cover;
}
.entry-content .person-right img{
    background-image: url("画像のURL");
    float: right;
}
.entry-content .person-left img{
    background-image: url("画像のURL");
    float: left;
}
.entry-content .person-right p,
.entry-content .person-left p{
    padding: 10px;
    position: relative;
    border: 1px solid #555;
    border-radius: 10px;
    box-sizing: border-box;
    width: calc(100% - 100px);
    margin-top: 16px;
}
.entry-content .person-left p{
    float: right;
}
.person-right p:before,
.person-right p:after,
.person-left p:before,
.person-left p:after{
    top: 13px;
}
.person-right p:before {
    content: '';
    border: 10px solid transparent;
    border-left: 15px solid black;
    position: absolute;
    left: 100%;
}
.person-right p:after {
    content: '';
    border: 10px solid transparent;
    border-left: 15px solid white;
    position: absolute;
    left: calc(100% - 1px);
}
.person-left p:before {
    content: '';
    border: 10px solid transparent;
    border-right: 15px solid black;
    position: absolute;
    right: 100%;
}
.person-left p:after {
    content: '';
    border: 10px solid transparent;
    border-right: 15px solid white;
    position: absolute;
    right: calc(100% - 1px);
}