body{
    background-color: rgb(28,45,82);
    margin-top: 10%;
    margin-left: 10%;
    margin-right: 10%;
    margin-bottom: 1%;

        

}






.card {
	margin:15px 5px;
}
.card h1{

    font-weight:bold;
	font-size:30px;
}

.card h2{ /*“使用建议”中的二级标题*/
	font-weight:bold; 
    font-size:18px;
}

#top-card div{
    margin: auto;
}

#Intro{
    margin:auto; 
}
#top-card{
    margin-bottom: 5%;
}
#Intro div{
    border: 0px;
    color: aliceblue;
    font-size: 24px;
    line-height: 150%;
    background-color: rgba(240, 248, 255, 0);
    
}

.col-md-6 div{
    color: black;
    background-color:white;
}


.col-md-4 div{
    color: rgb(0, 0, 0);
    background-color:white;
}

#blackcard{
    color:aliceblue;
    background-color: rgb(0, 128, 255);
}


#maintitel{
    font-family: 黑体;
    font-size: 36px;
    line-height: 150%;
    font-weight:bold;
    
}