body {
  margin: 0;
  font-family: 'Open Sans', sans-serif;
  background-color: #D8DCDE;
}

/*Header CSS*/
.header {
  width: 100%;
  height: 275px;
  margin: 0;
  border-bottom: 25px solid #000;
  opacity: 0.75;
}
header {
  width: 100%;
  height: 100%;
  background-image: url(http://www.cs.columbia.edu/~kathy/NLP/2021/images/CSBanner2.jpg);
  background-size: contain;
  text-align: center;
  color: #fff;
  margin: 0;
}
h1 {
  width: 100%;
  height: 50px;
  background-color: #000;
  padding-bottom: 20px;
  margin: 0;
}
h1, h2, h3 {
  font-family: font-family: 'Libre Franklin', sans-serif;
}

/*Main Section CSS*/
.mainSectionWrapper {
  width:  90%;
  margin-left: auto;
  margin-right: auto;
  background-color: #fff;
  margin-bottom: 100px;
  border: 1px solid #6D8494;
}
.tableCourseInfo, .navigation, .mainCourseDetails, .courseInfo .Homework0 {
  width: 80%;
  margin-left: auto;
  margin-right: auto;
}

.announce {
  width: 50%;
  color: #ff0000;
  margin-left: auto;
  margin-right: auto;
}

/*Table CSS*/
table {
  table-layout: fixed;
  width: 100%;
}
table, td {
  border: 1px solid black;
}
th {
  height: 30px;
  text-align: center;
  color: #fff;
  background-color: rgba(71, 78, 72, 0.8);
}
td {
  text-align: center;
  height: 60px;
}

.tableCourseInfo {
  border-collapse: collapse;
  width: auto;
}
.tableCourseInfo td {
  height: 20px;
  padding: 5px;
}

.tableTAInfo {
  border-collapse: collapse;
  width: auto;
  margin: auto;
}
.tableTAInfo td {
  height: 20px;
  padding: 5px;
}