img{margin-left: 20px; margin-right: 20px;}
p{margin-left: 15px; margin-right: 15px;}

.div_concurrent_img{padding: 10px 10px; display: flex; align-items:center; justify-content:center;}
@media(max-width: 768px) {
    .div_concurrent_img{flex-direction: column;}
}

.div_catalogue{
    padding: 10px 10px; 
    font-size: 16px; 
    word-spacing:0px;  
    border-radius: 10px;
    box-shadow: 10px 10px 5px #888888;
    background-color: #E0E0E0;
}

.div_catalogue_container{
    margin-bottom: 20px;
    padding: 10px 30px; 
    font-size: 16px; 
    word-spacing:0px;  
    border:1px solid black;
    border-radius: 10px;
}

.a_catalogue_title{
    font-weight: bold;
    color: darkslateblue;
}

.div_load_catalogue_alert{
    display: flex;
    align-items: center;
    justify-content: center;
    color: darkred;
    font-weight: bold;
}

.div_licence{
    font-size: 16px;
    word-spacing:0px; 
    border:1px solid black;
}

.div_code_segment{
    width:100%;
    border:1px solid rgb(128, 128, 128);
    border-radius: 15px;
    padding: 10px 10px;
    margin: 20px 10px;
}

.div_code_segment button{
    padding: 2px 8px;
    width: 100%;
}

.img {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: 0px;
    margin-bottom: 30px;
    justify-content: center;
}

.img img{
    margin: 0px;
    margin-bottom: 10px;
}

img_index {
    align-items: center;
    color: #000000;
    margin: 0px;
    background-color: #f0f0f0;
    padding: 2px 20px;
    font-size: 15px;
    border-radius: 8px;
}

.equation {
    margin-top: 20px;
    margin-bottom: 10px;
    padding: 10px 20px; 
    font-size: 16px; 
    word-spacing:0px;  
    border:1px solid black;
}

equation_index {
    font-family: Georgia, 'Times New Roman', Times, serif;
    background-color: #ff9b9b;
    color: #FFFFFF;
    padding: 2px 10px;
    margin-right: 10px;
    border-radius: 8px;
}

.theorm {
    margin-top: 20px;
    margin-bottom: 10px;
    padding: 10px 20px; 
    font-size: 16px; 
    word-spacing:0px;  
    border:1px solid black;
}

theorm_index {
    font-family: Georgia, 'Times New Roman', Times, serif;
    background-color: #888888;
    color: #FFFFFF;
    padding: 2px 10px;
    margin-right: 10px;
    border-radius: 8px;
}

.theorm_prove{
    background-color:#E3E2E2;
    padding: 10px 40px; 
    font-size: 16px;
    word-spacing:0px;  
    border-radius: 15px;
    margin-bottom: 15px;
}

.theorm_prove img{
    margin: 10px 10px;
}

.theorm_prove p{
    margin: 0px;
}

.div_learning_post{
    font-size: 16px;
    word-spacing:0px;
}

.div_indicate_source{
    font-size: 18px;
    word-spacing:0px;
    background-color: #E0E0E0;
}

.div_learning_post_border{
    margin-bottom: 20px;
    padding: 10px 10px; 
    font-size: 16px; 
    word-spacing:0px;  
    border:1px solid black;
}

.div_learning_post_background{
    background-color:#E3E2E2;
    padding: 10px 40px; 
    font-size: 16px;
    word-spacing:0px;  
    border-radius: 15px;
    margin-bottom: 15px;
}

.div_learning_post_background p{
    margin: 0px;
}

.div_ref{
    font-size: 16px;
    word-spacing:0px;
}