:root {
  --text-color-primary: #ffffffe6;
  --text-color-secondary: #808b9a;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 62.5%;
}

body {
  font-size: 1.6rem;
  line-height: 1.6;
  font-family: "Roboto", sans-serif;
  counter-reset: chapter;
}

.wrapper {
  width: 100%;
  display: flex;
  justify-content: center;
  background-color: antiquewhite;
}

.container {
  width: 450px;
  max-width: 100%;
  min-height: 100px;
  background-color: #272a31;
  display: flex;
  flex-direction: column;
  margin: 40px 0;
}

.top-chapter {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  border-bottom: 1px solid #181d1e;
  background-color: #272a31;
  padding: 20px;
  position: sticky;
  top: 0;
  z-index: 1;
  cursor: pointer;
  transition: background-color 0.3s ease-out;
}

.top-chapter i {
  font-size: 1.6rem;
  line-height: 1.6rem;
  color: var(--text-color-secondary);
  margin-top: 4px;
}

.chapter-info {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.chapter-info h2 {
  font-weight: 500;
  font-size: 1.8rem;
  color: var(--text-color-primary);
  counter-increment: chapter;
}

.chapter-info h2::before {
  content: counter(chapter) ". ";
}

.chapter-description {
  display: flex;
  gap: 4px;
}

.total-chapter,
.duration-chapter {
  color: var(--text-color-secondary);
  font-weight: 400;
  font-size: 1.2rem;
}

.total-chapter::after {
  content: "";
  border-right: 1px solid var(--text-color-secondary);
  padding-left: 4px;
}

.list-lesson {
  display: flex;
  flex-direction: column;
  counter-reset: lesson;
}

.item-lesson {
  flex: 1;
  border-bottom: 1px solid #181d1e;
}

.lesson-link {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 20px;
  text-decoration: none;
  transition: background-color 0.3s ease-out;
}

.lesson-link:hover,
.top-chapter:hover {
  background-color: #32353b;
}

.lesson-link i {
  font-size: 1.6rem;
  color: var(--text-color-secondary);
}

.lesson-descript {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.lesson-title {
  font-weight: 400;
  font-size: 1.4rem;
  color: var(--text-color-primary);
  counter-increment: lesson;
}

.lesson-title::before {
  content: counter(chapter) "." counter(lesson) " ";
}

.duration-lesson {
  color: var(--text-color-secondary);
  font-weight: 400;
  font-size: 1.2rem;
}