*,::after,::before {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body {
    background-color:#000;
    color:#fff;
}
header {
    font-size: 28px;
    font-family: sans-serif;
    text-align: center;
}
#navbar {
    min-width:320px;
    max-width: 350px;
    height: 100%;
    position: fixed;
    top: 0;
    left: 0;
    border-right: 5px solid #1eeb39;
}
#navbar > header {
    padding: 23px 0;
    font-size: 35px;
    position: fixed;
    top: 0;
    width: 320px;
    left: 0;
    border-bottom: 1px solid #fff;
}
#navbar > ul {
    margin-top: 10rem;
    overflow-y: auto;
    text-align: center;
    height: 71%;
    overflow-x: hidden;
}
#navbar > ul > li {
    margin: 30px 0;
    list-style-type: none;
    cursor: pointer;
    border-bottom: 1px solid #fff;
    padding: 12px;
}
#navbar > ul > li > a {
    text-decoration: none;
    color: orange;
    font-size: 28px;
    font-family: arial;
    letter-spacing: 1px;
}
#navbar > ul > li > a:hover {
    background:linear-gradient(45deg, rgb(192, 207, 192), yellow);
    border-radius:10px;
    color:rgb(15, 13, 14);
    width: auto;
    padding: 8px auto;
}
#navbar > ul > li > a:active {
    background: linear-gradient(90deg, #000, #fff);
    color:#fff;
    width: auto;
}
#main-doc {
    position: relative;
    margin-left: 320px;
    background-color: #fff;
    color: #000;
    height: auto;
    padding: 26px 4px;
    right: 0;
}
#main-doc > .main-section > header {
    border-radius: 14px;
    padding: 5px 23px;
    font-style: italic;
    background-color: #000;
    color:#abe019;
    width: auto;
    margin: 5px auto;
    border-radius: 15px;

}
.main-section {
    margin: 23px;
}
article > p > li {
    list-style-type: none;
}
article > h3 {
    font-size: 28px;
    font-family:Tahoma;
    letter-spacing: 1px;
    margin: 7px;
}
#Introduction > p, article > p , .main-section > p{
    font-size: 24px;
    letter-spacing: 0.5px;
    margin: 3px;
}
#main-doc li{
    margin: 17px 2px;
    font-size: 24px;
}
code {
    background-color: #000;
    color: orange;
    padding: 12px;
    margin: 12px;
    border-radius: 5px;
    display: block;
}

/* Media Queries */
@media (max-width: 1200px) {
    #navbar {
        width: 280px;
    }
    #navbar > header {
        width: 280px;
    }
    #main-doc {
        margin-left: 280px;
    }
}

@media (max-width: 992px) {
    #navbar {
        width: 240px;
    }
    #navbar > header {
        width: 240px;
    }
    #main-doc {
        margin-left: 240px;
    }
}

@media (max-width: 768px) {
    #navbar {
        width: 200px;
    }
    #navbar > header {
        width: 200px;
    }
    #main-doc {
        margin-left: 200px;
    }
}

@media (max-width: 576px) {
    #navbar {
        width: 160px;
    }
    #navbar > header {
        width: 160px;
    }
    #main-doc {
        margin-left: 160px;
    }
    #navbar > ul > li > a {
        font-size: 24px;
    }
}

@media (max-width: 400px) {
    #navbar {
        position: static;
        width: 100%;
        height: auto;
        border-right: none;
        /* border-bottom: 5px solid #1eeb39; */
    }
    #navbar > header {
        position: static;
        width: 100%;
        border-bottom: 1px solid #fff;
    }
    #navbar > ul {
        margin-top: 0;
        height: auto;
    }
    #navbar > ul > li:last-of-type {
       border-bottom: none;
    }
    #main-doc {
        margin-left: 0;
        margin-top: 10px;
    }
}