styles.css

/* CSS custom properties */
:root {
  --color-background-primary: white;
  --color-background-secondary: whitesmoke;
  --color-background-tertiary: #ddd;
  --color-background-highlight: #0069c220;
  --color-text: #222;
  --color-gray: #555;
  --color-grayish: #858585;
  --color-blue: #3366cc;
  --color-red: #d30038;
  --color-green: #007936;

  --font-family: "Open Sans", Arial, sans-serif;
  --border: 1px solid DarkGray;
  scroll-behavior: smooth;
}

/* BEM Mixes */
.text--blue {
  color: var(--color-blue);
}

.text--red {
  color: var(--color-red);
}

.text--green {
  color: var(--color-green);
}

.text--gray {
  color: var(--color-grayish);
}

/* CSS Styling - BEM Methodology */
.l-body {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  justify-content: center;
  align-items: center;
}

.l-header {
  box-sizing: border-box;
  margin: 0;
  padding: 0 1rem 0 1.5rem;
  position: fixed;
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: space-between;
  row-gap: 0;
  width: 100%;
  height: 3rem;
  background-color: var(--color-background-primary);
  border-bottom: var(--border);
  font-family: var(--font-family);
  color: var(--color-text);
  z-index: 1;
}

.header__heading {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-size: 1.2rem;
  font-weight: 400;
  line-height: 2rem;
}

.header__hamburger-menu {
  z-index: 1;
  position: fixed;
  padding: 0;
  top: 0.5rem;
  right: 0.5rem;
  width: 2rem;
  height: 2rem;
  line-height: 2rem;
  vertical-align: center;
  text-align: center;
  color: #555;
  background-color: var(--color-background-primary);
  border-width: 0px;
  visibility: hidden;
}

.header__hamburger-menu:hover {
  background-color: var(--color-background-tertiary);
  border-radius: 4px;
  cursor: pointer;
}

.l-main {
  display: flex;
  flex-direction: column;
  align-items: center;
  row-gap: 0;
  box-sizing: border-box;
  margin: 0;
  padding: 0 2.5rem 2.5rem;
  width: calc(100% - 220px);
  position: relative;
  left: 0px;
  top: 0;
}

.main-section {
  box-sizing: border-box;
  width: 100%;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  row-gap: 1.5rem;
  font-family: var(--font-family);
  color: var(--color-text);
  line-height: 1.5;
}

.main-section__heading {
  box-sizing: border-box;
  margin: 4.25rem 0 0 0;
  padding: 0;
  font-size: 1.8rem;
  font-weight: 400;
  line-height: 2rem;
}

.main-section__text-block {
  box-sizing: border-box;
  margin: 0;
  padding: 0 0 0 1rem;
  font-size: 0.9rem;
}

.main-section__list {
  box-sizing: border-box;
  margin: 0;
  padding: 0 0 0 3rem;
  display: flex;
  flex-direction: column;
  row-gap: 1rem;
}

.main-section__list--inner {
  box-sizing: border-box;
  margin: 1rem 0 0;
  padding: 0 0 0 2rem;
  display: flex;
  flex-direction: column;
  row-gap: 1rem;
}

.main-section__list-item {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-size: 0.9rem;
}

.main-section__code-block {
  box-sizing: border-box;
  margin: 0 0.5rem 0 1rem;
  padding: 1rem;
  background-color: var(--color-background-secondary);
  border-radius: 4px;
  font-size: 0.8rem;
  line-height: 1.5rem;
  color: var(--color-gray);
}

.main-section__inline-code {
  box-sizing: border-box;
  margin: 0;
  padding: 0.125rem 0.25rem;
  background-color: var(--color-background-secondary);
  font-size: 0.8rem;
  line-height: 1.5rem;
  color: var(--color-gray);
}

.main-section__link {
  color: var(--color-blue);
  text-decoration: underline;
}

.main-section__link:hover {
  text-decoration: none;
}

.l-nav {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  position: fixed;
  top: 3rem;
  right: 0;
  width: 220px;
  height: 100%;
  display: flex;
  flex-direction: column;
  row-gap: 0.75rem;
  font-family: var(--font-family);
  transition: right 0.2s ease;
}

.nav__heading {
  box-sizing: border-box;
  margin: 1rem 0 0 0;
  padding: 0;
  font-size: 1.2rem;
  font-weight: 400;
  line-height: 2rem;
  color: var(--color-text);
}

.nav__list {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  row-gap: 0;
  border-left: var(--border);
  font-size: 0.8rem;
}

.nav__list-item {
  box-sizing: border-box;
  margin: 0;
  padding: 0 0 0 1rem;
  list-style-type: none;
  line-height: 2rem;
}

.nav__list-item--highlight {
  background-color: var(--color-background-highlight);
  border-left: 1px solid var(--color-blue);
  margin-left: -1px;
}

.nav__link {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  color: var(--color-text);
  text-decoration: none;
}

.nav__link:hover {
  color: var(--color-blue);
  text-decoration: none;
}

/* Big monitors (>1329px) */
@media screen and (min-width: 1329px) {
  .l-main {
    position: relative;
    left: calc((100vw - 1328px) / 2);
    max-width: calc(1328px - 250px);
  }

  .l-nav,
  .l-nav--active {
    right: calc((100vw - 1328px) / 2);
  }
}

/* Tablet and mobile (0-768px) */
@media screen and (max-width: 768px) {
  .l-main {
    width: 100%;
  }

  .header__hamburger-menu {
    visibility: visible;
  }

  .l-nav {
    padding-left: 1rem;
    right: calc(-220px - 1rem);
    width: calc(220px + 1rem);
    background-color: var(--color-background-primary);
    border-left: var(--border);
    transition: right 0.2s ease;
    z-index: 1;
  }

  .l-nav--active {
    right: 0;
  }

  .nav__heading {
    padding-left: 0.2rem;
  }

  .nav__list {
    border-left: unset;
  }
}