body {
    max-width: 900px;
    margin: auto;
    font-family: sans-serif;
    padding-left: 23px;
    padding-right: 23px;
}

ul {
    list-style-type: decimal-leading-zero;
    margin-left: 0px;
    line-height: 22px;
    padding-left: 30px;
}


a {
    text-decoration: none;
    color: black;   
}

a:hover {
    color: gray;
    text-decoration: underline;
}

h1 {
    text-align: center;
    font-size: 50px;
    text-transform: uppercase;
}

h2 {
    margin-top:60px;
}

img {
    width: 100%;
    margin-bottom: 30px;
}

p {
    line-height: 22px;
}

blockquote {
    font-style: italic;
    color: darkgray;
}


#collapseContent {
    display: none;
}

.contentTitle {
    text-align: center;

    
}

.contentTitle:hover {
    color: darkgray;
    cursor: pointer;
    
}

#back-to-top {
    position: fixed;
    bottom: 13px;
    left: 13px;
    border: none;
    
    width: 120px;
    height: 40px;
    font-size: 14px;
    font-weight: bold;
    
    background-color: lightgray;
    
}

#back-to-top:hover {
    cursor: pointer;
}

#toc {
   max-width: 400px;
    margin: auto;
}

@media (max-width: 900px) {
    
    #back-to-top {
        width: 100%;
        height: 60px;
        bottom: 0;
        left: 0;
        background-color: #EDEDED;
        border-top: solid;
        border-top-width: 2px;
        border-top-color: lightgray;   
    }
    
    img {
        margin-bottom: 10px;
    }

    .contentTitle {
        margin-top: 36px;
        margin-bottom: 0px;
    }
    
    h1 {
        font-size: 40px;
    }
}