webapp/src/components/Nav/Header.scss

header {
  margin-bottom: 2.2rem;
  position: sticky;
  top: 0;
  z-index: 10;

  .wide-container {
    background: #fff;

    @include media-breakpoint-down(sm) {
      padding: 0 divide($container-padding-x, 2);
    }
  }
}

.header__inner {
  background: #fff;
  border-bottom: 4px solid #000;
  flex-wrap: nowrap;
  justify-content: space-between;
  margin: 0;

  &.fixed {
    border-bottom: 4px solid #000;
    left: 0;
    position: fixed;
    right: 0;
    top: 0;
    padding: 0 divide($container-padding-x, 2);
    z-index: 9;

    @include media-breakpoint-up(sm) {
      padding: 0 $container-padding-x;
    }
  }
}

.main-logo {
  align-items: center;
  display: inline-flex;
  height: 70px;
  padding: 0 $container-padding-x 0 0;
  text-align: center;
  position: relative;
  z-index: 9;

  @include media-breakpoint-up(lg) {
    height: 80px;
  }

  img {
    vertical-align: middle;
    width: 100px;

    @include media-breakpoint-up(lg) {
      width: 175px;
    }
  }

  a {
    border: none;
    color: #000;

    &:hover {
      background: none;
    }
  }
}

nav {
  align-items: center;
}

.usernav {
  display: inline-flex;
  padding-right: 0;
  width: auto;

  @include media-breakpoint-down(md) {
    flex: 1;
    padding-left: 0;
    padding-right: 0;
  }
}

.main-navigation {
  display: inline-flex;
  @include font-size(1.7rem);

  list-style: none;
  margin: 0;
  padding: 0;

  @include media-breakpoint-down(md) {
    background: #fff;
    bottom: 0;
    display: none;
    font-size: 2.6rem;
    font-weight: bold;
    left: 0;
    padding: $container-padding-x;
    position: fixed;
    top: 74px;
    width: 100%;
    z-index: 1;

    li {
      margin-bottom: 2.4rem;
    }
  }

  @include media-breakpoint-down(sm) {
    padding: divide($container-padding-x, 2);
  }

  &.fixed {
    display: inline-flex;

    @include media-breakpoint-down(lg) {
      display: block !important;
    }
  }

  li {
    margin-right: 2.4rem;
  }

  a {
    border: none;
  }

  .selected a {
    border-bottom: 2px solid;
    color: #000;
    pointer-events: none;
    cursor: default;
  }
}

.burger-container {
  box-sizing: content-box;
  display: inline-flex;
  float: right;
  padding-right: 0;
  padding-left: 0;
  width: 2.2rem;

  @include media-breakpoint-up(sm) {
    padding-left: divide($container-padding-x, 2);
  }

  @include media-breakpoint-up(md) {
    display: none;
  }
}

.burger {
  background: #fff;
  cursor: pointer;
  height: 1.8rem;
  display: inline-block;
  position: relative;
  vertical-align: middle;
  width: 2.2rem;

  > div,
  &::after,
  &::before {
    background: #000;
    content: '';
    display: block;
    height: 2px;
    left: 0;
    position: absolute;
    width: 100%;
  }

  > div {
    margin-top: -1px;
    opacity: 1;
    top: 50%;
    transition: opacity 0.2s 0.1s;
  }

  &::after,
  &::before {
    transform-origin: center !important;
    transition: top 0.3s, transform 0.3s;
  }

  &::after {
    bottom: 0;
  }

  &::before {
    top: 0;
  }

  &.fixed {
    > div {
      opacity: 0;
      transition: opacity 0s;
    }

    &::after {
      bottom: 0.8rem;
      transform: rotate(-45deg);
    }

    &::before {
      transform: rotate(45deg);
      top: 0.8rem;
    }
  }
}