styles.css

* {
  font-family: sans-serif;
}

.header {
  text-align: center;
  margin-top: 40px;
}

.box {
  border: 2px solid #000!important;
  width: 70%;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

#toc_container {
  background: #f9f9f9;
  border: 1px solid #aaa;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  font-size: 95%;
  width: 70%;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: 40px;
  padding-top: 20px;
  padding-bottom: 20px;
}

.toc_title {
  width: 70%;
  font-weight: 700;
  text-align: center;
  margin-top: 0px;
  margin-bottom: 0;
}

#toc_container li, #toc_container ul, #toc_container ul li {
  list-style: outside none none !important;
}

.toc_list {
  vertical-align: top;
  margin: 15px;
  text-align: center;
  padding-left: 0;
}

.toc_list > li {
  margin-bottom: 5px;
}

.see_more {
  text-align: center;
  margin-bottom: 50px;
}

.footer_text {
  margin: 0;
  font-size: 12px;
  text-align: center;
}

footer {
  border-top: 1px solid grey;
  margin-top: 5px;
  margin-bottom: 30px;
  padding-top: 15px;
}

.spacing {
  margin-top: 0px;
}

.section_header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  width: 90%;
  margin-top: 40px;
  margin-left: auto;
  margin-right: auto;
}

.left {
  float: left;
  margin-left: 8%;
  margin-top: 5px;
  margin-bottom: 10px;
}

.right {
  float: right;
  margin-right: 8%;
  margin-top: 5px;
  margin-bottom: 10px;
}

.page_title {
  width: 700px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  margin: auto;
}

.text_body {
  width: 100%;
  margin-top: 25px;
  margin-left: auto;
  margin-right: auto;
  max-width: 65%;
}

.bottom_nav {
  display: inline-block;
  margin-top: 10px;
  width: 100%;
  margin-bottom: 40px;
}

.centered-img {
  margin-left: auto;
  margin-right: auto;
  margin-bottom: 10px;
  display: block;
  width: 50%;
  max-width: 500px;
}

.centered-img-vert {
  margin-left: auto;
  margin-right: auto;
  margin-bottom: 10px;
  display: block;
  max-width: 60%;
  max-height: 350px;
}

.centered-img-caption {
  text-align: center;
  display: block;
  margin-right: auto;
  margin-left: auto;
}

@media screen and (max-width: 772px) {
  .section_header {
    display: flex;
    flex-wrap: wrap;
    width: 260px;
    margin-top: 40px;
    text-align: center;
    justify-content: space-around;
    align-items: center;
    margin-left: auto;
    margin-right: auto;
  }
  .section_header a {
    margin-bottom: 10px;
  }
  .left {
    float: left;
    margin-top: 5px;
    margin-bottom: 10px;
    margin-right: 0px;
  }
}

@media screen and (max-width: 700px) {
  #toc_container {
    width: 88%;
    font-size: 100%;
  }
  .toc_list li {
    margin-bottom: 10px;
  }
}

@media screen and (max-width: 900px) {
  .text_body {
    width: 100%;
    margin-top: 25px;
    margin-left: auto;
    margin-right: auto;
    max-width: 75%;
  }
}

@media screen and (max-width: 640px) {
  .text_body {
    width: 100%;
    margin-top: 20px;
    margin-left: auto;
    margin-right: auto;
    max-width: 80%;
  }

  .page_title {
    font-size: 20px;
    width: 500px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    text-align: center;
    margin: auto;
  }
}

@media screen and (max-width: 480px) {
  .left {
    float: left;
    margin-left: 10px;
    margin-top: 5px;
    margin-bottom: 10px;
  }

  .right {
    float: right;
    margin-right: 10px;
    margin-top: 5px;
    margin-bottom: 10px;
  }

  .text_body {
    width: 100%;
    margin-top: 15px;
    margin-left: auto;
    margin-right: auto;
    max-width: 100%;
  }

  .page_title {
    width: 300px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    text-align: center;
    margin: auto;
  }
}