* {
  box-sizing: border-box;
}

body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  background-color: rgb(37, 52, 37);
}

header {
  width: 100%;
  background-color: forestgreen;
  color: white;
  text-align: center;
  padding: 1px 0;
}

nav {
  position: sticky;
  top: 0;
  width: 100%;
  z-index: 1;
}

nav ul {
  list-style: none;
  padding: 0;
  background-color: rgb(65, 87, 65);
  margin: 0;
}

nav ul li {
  display: inline;
  margin-right: 10px;
}

nav ul li a {
  color: white;
  text-decoration: none;
  padding: 10px 20px;
  display: inline-block;
}

nav ul li a:hover {
  background-color: rgb(94, 124, 94);
}

main {
  padding: 1em 1em;
  color: white;
  min-height: calc(100vh - 3.34em - 1em - 20px - 2em - 4.5em);
  /* 3.34em header, 1em+20px nav, 2em main padding, 4.5em footer */
}

.courses-container {
  display: flex;
  flex-wrap: wrap;
  gap: 2em;
  width: 100%;
  justify-content: center;
}

.course-unit {
  border-radius: 1em;
  background-color: rgb(65, 87, 65);
  padding: 1em;
  font-weight: bold;
  width: 45%;
  min-width: 20em;
}

.unit-title {
  text-align: center;
  font-size: 1.5em;
  padding-bottom: 0.5em;
}

.section-container {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5em;
  align-items: flex-start;
}

.course-section {
  margin: 0.5em;
  min-width: 5em;
}

.section-name {
  color: rgb(94, 124, 94);
  border-radius: 1em;
  padding: 0.5em 1em;
  background-color: rgb(37, 52, 37);
  text-align: center;
}

.section-progress-bar {
  width: 100%;
  height: 0.3em;
  margin-top: 0.5em;
  background-color: rgb(94, 124, 94);
  border-radius: 0.15em;
}

.section-progress {
  background-color: coral;
  width: 0%;
  height: 100%;
  border-radius: 0.15em;
}

footer {
  font-size: 1em;
  text-align: center;
  padding: 0.5em 0;
  background-color: rgb(65, 87, 65);
  color: white;
  width: 100%;
}

@media (max-width: 700px) {
  .course-unit {
    width: 95%;
  }
}