html {
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
}

body {
  margin: 0;
}

.promo {
  height: 300px;
  background-image: url("https://mate-academy.github.io/fe-program/assets/MA_top.jpg");
  background-size: cover;
  background-repeat: no-repeat;
  background-position: top center;
}

.header {
  position: sticky;
  top: 0;
  background: rgba(0,0,0,0.8);
  backdrop-filter: saturate(180%) blur(20px);
}

.main {
  padding: 10px 20px;
  background-color: antiquewhite;
}

/* #region Nav */
.nav {
  text-align: center;
}

@media (min-width: 640px) {
  .nav__toggler {
    display: none;
  }
}

.nav__list {
  height: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  overflow: hidden;
}

.nav--open .nav__list {
  height: auto;
}

.nav__toggler::before {
  content: '=';
}

.nav--open .nav__toggler::before {
  content: 'x';
}

@media (min-width: 640px) {
  .nav__list {
    display: flex;
    justify-content: center;
    height: auto;
  }
}

.nav__link {
  display: block;
  padding: 10px 5px;
  margin: 0 15px;

  font-size: 20px;
  color: #fff;
  text-decoration: none;
}

.nav__link:hover {
  color: #ff0;
  background-color: #111;
}
/* #endregion Nav */

.footer {
  position: sticky;
  bottom: 0;
  z-index: -1;
  
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;

  height: 300px;

  color: #fff;

  background-image: url("https://mate-academy.github.io/fe-program/assets/MA_bottom.jpg");
  background-size: cover;
  background-position: top;
}