html, body {
  position: relative;
  height: 100%;
}

header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  display: flex;
  align-items: center;
  padding: 20px;
  z-index: 9;
}

header.sticky {
  background-color: #fff;
  box-shadow: 0px 0px 12px rgba(0, 0, 0, .12);
}

.logo {
  width: 50px;
  margin-left: 10%;
}

nav {
  margin-left: 50px;
}

nav ul {
  display: flex;
  align-items: center;
  list-style: none;
  padding: 0;
  margin: 0;
}

nav ul li {
  position: relative;
  font-size: 13px;
  color: #666;
  cursor: pointer;
  margin-right: 30px;
  transition: all 0.1s;
}

nav ul li.active {
  color: #C8102E;
  font-weight: 600;
}

nav ul li.active::before {
  content: '';
  position: absolute;
  bottom: -6px;
  width: 100%;
  height: 2px;
  background-color: #C8102E;
}

main img {
  width: 100%;
}

footer {
  opacity: 0;
  margin-top: -30px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  color: #808080;
}

footer a {
  display: flex;
  align-items: center;
  text-decoration: none;
  color: #808080;
}

footer a:hover {
  color: #C8102E;
}

@media screen and (max-width: 768px) {
  header {
    padding-right: 0;
  }

  .logo, nav ul li {
    margin: 0;
  }

  nav {
    flex: 1;
    margin-left: 30px;
  }

  nav ul li {
    margin-right: 15px;
  }
}