survey/templates/panel/nav/mobile.scss

$hamburger-menu-animation: 0.4s ease-out;
$nav__hamburger-inner-height: 1.3px;

.nav__container {
  flex-direction: column;
}

.nav__header {
  display: flex;
  flex-direction: row;
  min-width: 100%;
  height: 55px;
  justify-content: space-between;
}

.nav__link-group {
  position: sticky;
  flex-direction: column;
}

.nav__hamburger-menu {
  display: inline-block;
  width: 50px;
  height: 50px;
}

.nav__spacer {
  display: none;
}

.nav__toggle:not(:checked) ~ .nav__link-group {
  max-height: 0;
  transition: max-height $hamburger-menu-animation;
  overflow: hidden;
}

.nav__toggle:checked ~ .nav__link-group {
  max-height: 500px;
  transition: max-height $hamburger-menu-animation;
}

.nav__toggle:checked ~ .nav__header {
  .nav__hamburger-inner::after {
    width: 24px;
    bottom: $nav__hamburger-inner-height;
    transform: rotate(-90deg);
    transition: bottom 0.1s ease-out,
      transform 0.22s cubic-bezier(0.215, 0.61, 0.355, 1) 0.12s,
      width 0.1s ease-out;
  }

  .nav__hamburger-inner::before {
    top: 0;
    opacity: 0;
    transition: top 0.1s ease-out, opacity 0.1s ease-out 0.12s;
  }

  .nav__hamburger-inner {
    transform: rotate(225deg);
    transition-delay: 0.12s;
    transition-timing-function: cubic-bezier(0.215, 0.61, 0.355, 1);
  }
}

.nav__hamburger-inner::after {
  bottom: -7px;
  transition: bottom 0.1s ease-in 0.25s,
    transform 0.22s cubic-bezier(0.55, 0.055, 0.675, 0.19),
    width 0.1s ease-in 0.25s;
}

.nav__hamburger-inner::after,
.nav__hamburger-inner::before {
  content: '';
  display: block;
}

.nav__hamburger-inner::before {
  top: -7px;
  transition: top 0.1s ease-in 0.25s, opacity 0.1s ease-in;
}

.nav__hamburger-inner {
  top: 50%;
  margin: auto;
  transition-duration: 0.22s;
  transition-timing-function: cubic-bezier(0.55, 0.055, 0.675, 0.19);
}

.nav__hamburger-inner,
.nav__hamburger-inner::after,
.nav__hamburger-inner::before {
  width: 24px;
  height: $nav__hamburger-inner-height;
  position: relative;
  background: #000;
}

.nav__hamburger-menu,
.nav__hamburger-inner {
  display: block;
}