:root {
  --nav-bg-color-main: var(--nav-bgc-main, #172f82);
  --nav-bg-color-secondary: var(--nav-bgc-sec, #167aa8);
  --nav-color: var(--nav-c-main, #ffffff);
  --nav-color-secondary: var(--nav-c-sec, #f2f2f2);
  --nav-duration-transition: var(--nav-duration-trans, 800ms);
}

.nav-box {
  position: fixed;
  top: 0;
  left: 0;
  overflow: visible;
  width: 100%;
}

.nav-cycle {
  position: absolute;
  display: flex;
  top: -1em;
  left: calc(50vw - (75vmin/2));
  width: 75vmin;
  aspect-ratio: 1 / 1;
  border-radius: 50%;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background-color: var(--nav-bg-color-main);
  color: var(--nav-color);
  opacity: 0.8;
  box-shadow: 0 0 .5em .5em var(--nav-bg-color-main);
  transform-origin: center 2.5em;
  transform: rotate(-180deg);
}

.closed {
  transform: rotate(180deg);
  transition: transform var(--nav-duration-transition) ease-in-out;
}

#nav-rotate:checked ~ .closed {
  transform: rotate(0deg);
}

.opened {
  transform: rotate(-180deg);
}

#nav-rotate:checked ~ .opened {
  transform: rotate(0deg);
  transition: transform var(--nav-duration-transition) ease-in-out;
}

#nav-rotate {
  display: none;
}

.nav-cycle > .nav-menu-button,
.nav-cycle > .nav-menu-button:before,
.nav-cycle > .nav-menu-button:after {
  display: block;
  background-color: var(--nav-color);
  position: absolute;
  left: calc(50% - 15px);
  top: calc(2.5em - 2px);
  height: 4px;
  border-radius: 2px;
  width: 30px;
  transform: rotate(-180deg);
  transition: all var(--nav-duration-transition) ease-in-out;
}

.nav-cycle > .nav-menu-button:before {
  content: '';
  top: -.5em;;
}

.nav-cycle > .nav-menu-button:after {
  content: '';
  top: .5em;
}

#nav-rotate:checked ~ .nav-cycle > .nav-menu-button {
  transform: rotate(0deg);
  background: rgba(0, 0, 0, 0);  /* transparent */
}


#nav-rotate:checked ~ .nav-cycle > .nav-menu-button:before {
  top: 0em;
  transform: rotate(315deg);
}

#nav-rotate:checked ~ .nav-cycle > .nav-menu-button:after {
  top: 0em;
  transform: rotate(-675deg);
}

.nav-menu {
  display: flex;
  flex-direction: column;
  list-style-type: none;
  justify-content: center;
  align-items: center;
  margin: 0;
  padding: 0;
  font-size: 16px;
}

.nav-menu > li {
  display: flex;
  margin: 0;
  padding: 0.25em 0;
  overflow: hidden;
}

.nav-menu a {
  text-decoration: none;
  color: var(--nav-color);
}

.nav-menu a:hover {
  text-decoration: underline;
  color: var(--nav-color-secondary);
}