.topBar{
    position: sticky;
    width: 100%;
    top: 0px;
    background-color: #f5f5f5;
    margin: 20px 0px;
    z-index: 2;
}
.nav {
    /* margin-left: 45%; */
    display: flex;
    /*设置为flex布局*/
    justify-content: center;
    /*水平居中*/
    align-items: center;
    /*垂直居中*/
}

.nav ul {
    list-style: none;
    display: flex;
    justify-content: space-between;
    width: 650px;
}

.nav ul li {
    display: inline-block;
    margin-right: 100px;
    position: relative;
}

.nav .selected>a::before {
    content: "";
    width: 31px;
    height: 3px;
    background-color: #2076FE;
    position: absolute;
    top: 30px;
    left: 23px;
}

.userLogin {
    display: inline-block;
    /* text-align: center; */
    text-decoration: none;
    color: rgb(194, 190, 190);
    font-size: 20px;
}

.active {
    color: #242320 !important;
    font-weight: 600;
    /* border-bottom: 3px solid #156FFC; */
    padding-bottom: 10px;
}

.container{
    width: 100%;
    display: flex;
    justify-content: center;
    position: relative;
    /* top: 190px; */
}
.center{
    width: 1200px;
    height: auto;
    /* background-color: aliceblue; */
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
.card{
    width: 1200px;
    height:auto ;
    background-color: #ffffff;
    border-radius: 18px;
    padding: 20px 20px 20px 20px;
    margin-bottom: 30px;
}
.message{
    display: flex;
    justify-content: space-between;
    align-items: baseline;
}
.personMsg img{
    /* border-radius: 100%; */
    width: 50px;
    height: 50px;
}
.personMsg{
    display: flex;
}
.personMsg .user{
    width: 150px;
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    margin-left: 15px;
}
.cardBottom{
    display: flex;
    justify-content: space-between;
    margin-top: 50px;
    align-items: flex-end;
}
.answerBtn{
    color: #ffffff;
    width: 120px;
    height: 36px;
    border-radius: 18px;
    background-color: #000000;
    border: none;
    font-size: 14px;
}
@media screen and (max-width:1470px){
    .font24{font-size: 20px;}
    .font16{font-size: 14px;}
    .font14{font-size: 12px;}
    .card{width: 900px;}
    .topBar{margin: 0;}
    .nav ul{width: 550px;}
    .reaction{font-size: 14px;}
    .cardBottom{margin-top: 20px;}
}
@media (max-width: 1300px){
    .card{
        width: 800px;
        margin: 15px auto;
    }
}
@media (max-width: 820px){
    .card{
        width: 400px;
    }
    .title{
        font-size: 20px;
    }
}