body{
    background-color: #f2f3f2;
}

.container{
    background-color: white;
    margin: 10px auto 20px;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0,0,0,.15);
}

h1{
    margin-bottom: 20px;
    border-bottom: 1px dashed #999;
}

p{
    font-size: 16px;
    color: #333;
}

img{
    max-width: 50%;
}

.backTop{
    position: fixed;
    top: 70%;
    right: 0;
    background-color: #2979ff;
    width: 50px;
    height: 50px;
    box-sizing: border-box;
    padding: 5px;
    border-radius: 5px;
    cursor: pointer;
    display: none;
}
.backTop img{
    width: 100%;
    max-width: none;
}