nav
  input.toggle#nav(type="checkbox")
  label.label(for="nav")
    p Menu
    span.hum
    ul.list
      li.list__home: a(href="#0") Home
      li.list__about: a(href="#0") About
      li.list__clients
        a(href="#0")
          span Clients
        ul.list__clientsItems
          li: a(href="#0") Burger King
          li: a(href="#0") Southwest Airlines
          li: a(href="#0") Levi Strauss
      li.list__strauss
        a(href="#0")
          span Services
        ul.list__straussItem
          li: a(href="#0") Print Design
          li: a(href="#0") Web Design
          li: a(href="#0") Mobile App Development
      li.list__contact: a(href="#0") Contact

$BG: #e2eff1;
$TOGGLE: #e23e57;
$TOGGLE2: #65799b;
$TOGGLE3: #555273;
$BORDER: #555273;
$FONT: #e2eff1;

$TOGGLE_SIZE: 100px;

@import url("https://fonts.googleapis.com/css?family=Cute+Font&display=swap");

@mixin prefixes($property, $value) {
  @each $prefix in -webkit-, -moz-, -ms-, -o-, "" {
    #{$prefix}#{$property}: $value;
  }
}

%input {
  position: absolute;
  opacity: 0;
  bottom: 0;
  z-index: -1;
  @include prefixes(transform-origin, bottom center);
  @include prefixes(box-sizing, border-box);

  &:after {
    top: 100px;
    width: 1px;
    height: 100%;
    background: $BORDER;
    z-index: -1;
  }
  a {
    display: flex;
    width: 100px;
    height: 100px;
    @include prefixes(align-items, center);
    margin: auto;
    justify-content: center;
    -webkit-box-pack: center;
    -ms-flex-pack: center;
    border-radius: 50%;
    line-height: 1;
    color: $FONT;
    @include prefixes(box-sizing, border-box);

    &:visited,
    &:active {
      color: $FONT;
    }
    &:hover {
      color: #fff;
    }
  }
}

%inputCheck {
  opacity: 1;
  z-index: 0;
}

nav {
  position: relative;
  margin: auto;
  width: 500px;
  height: 100%;
  @include prefixes(transform, scale(0.8));
}

ul {
  padding: 0;
  margin: 0;
  font-size: 30px;
  text-align: center;
}

li {
  list-style: none;
}

.toggle {
  opacity: 0;
  &:checked {
    & + .label {
      .hum {
        @include prefixes(transition, 0.8s);
        @include prefixes(transform, rotate(45deg) translate(10px, 10px));
        &:before {
          @include prefixes(transition, 0.8s);
          @include prefixes(transform, rotate(-90deg) translate(10px, 0px));
        }
        &:after {
          opacity: 0;
          @include prefixes(transition, 0.8s);
          @include prefixes(transform, rotate(-90deg) translate(20px, 0px));
        }
      }
      .list {
        &__home {
          @extend %inputCheck;
          opacity: 1;
          height: 200px;
          @include prefixes(transition, 0.8s);
        }
        &__about {
          @extend %inputCheck;
          opacity: 1;
          height: 200px;
          @include prefixes(transition, 0.8s);
        }
        &__clients {
          @extend %inputCheck;
          opacity: 1;
          @include prefixes(transition, 0.8s);
          @include prefixes(transform, translate(200px, -200px) rotate(45deg));

          &:after {
            height: 36px;
            @include prefixes(transition, 1.1s);
          }
          li {
            opacity: 0;
          }
        }
        &__strauss {
          @extend %inputCheck;
          opacity: 1;
          @include prefixes(transition, 0.8s);
          @include prefixes(transform, translate(90px, -260px) rotate(-135deg));

          &:after {
            height: 36px;
            @include prefixes(transition, 1.1s);
          }
        }
        &__clientsItems {
          &:nth-of-type(1) {
            height: 0;
          }
        }
        &__contact {
          @extend %inputCheck;
          opacity: 1;
          height: 200px;
          @include prefixes(transition, 0.8s);
        }
      }
    }
  }
}

.label {
  position: absolute;
  top: calc(50% - (100px / 2));
  left: calc(50% - (100px / 2));
  width: $TOGGLE_SIZE;
  height: $TOGGLE_SIZE;
  background-color: $TOGGLE;
  border-radius: 50%;
  z-index: 10;
}

.list {
  position: absolute;
  top: -200px;
  left: calc(50% - 250px);
  width: 500px;
  height: 500px;
  @include prefixes(transform-origin, center);

  &__home {
    @extend %input;
    height: 10px;
    transform: translate(200px, -300px);
    -webkit-transform: translate(200px, -300px);
    overflow: hidden;
    @include prefixes(transition, 0.8s);
    @include prefixes(transform, translate(200px, -300px));

    a {
      background: $TOGGLE2;
    }
  }
  &__about {
    @extend %input;
    height: 10px;
    overflow: hidden;
    transform: translate(158px, -275px) rotate(-45deg);
    @include prefixes(transform,  translate(158px, -275px) rotate(-45deg));
    @include prefixes(transition, 0.8s);
    a {
      background: $TOGGLE2;
      @include prefixes(transform,  rotate(45deg));
    }
  }
  &__clients {
    @extend %input;
    width: 300px;
    height: 300px;
    @include prefixes(transition, 0.8s);
    @include prefixes(transform,  translate(100px, -110px) rotate(45deg));

    a {
      background: $TOGGLE2;
      span {
        @include prefixes(transform,  rotate(-45deg));
      }
    }
    &:after {
      top: 250px;
      width: 1px;
      height: 0;
      background: $BORDER;
      left: 45px;
      @include prefixes(transition, 0.3s);
    }
    .list__clientsItems {
      @include prefixes(transition, 0.8s);
      li {
        @extend %input;
        @include prefixes(transition, 0.8s);
        opacity: 0;
        width: 100px;
        height: 0;
        overflow: hidden;
        &:after {
          z-index: -1;
        }
        a {
          margin: 0 0 auto 0;
          background: $TOGGLE3;
        }
        &:after {
          top: 100px;
          left: 50px;
        }
        &:nth-of-type(1) {
          @include prefixes(transform,  scale(0.8) translate(-15px, -155px) rotate(-20deg));

          a {
            @include prefixes(transform,  rotate(-25deg));
          }
        }
        &:nth-of-type(2) {
          font-size: 22px;
          @include prefixes(transform,  scale(0.8) translate(20px, -148px) rotate(30deg));

          a {
            @include prefixes(transform, rotate(-75deg));
          }
        }
        &:nth-of-type(3) {
          @include prefixes(transform,  scale(0.8) translate(33px, -107px) rotate(120deg));

          &:after {
            top: 100px;
            @include prefixes(transition, 0s);
          }
          a {
            @include prefixes(transform, rotate(195deg));
          }
        }
      }
    }
    &:hover {
      opacity: 1;
      ul,
      li {
        display: flex;
        display: -webkit-box;
        display: -ms-flexbox;
        @include prefixes(align-items, center);
      }
      .list__clientsItems {
        @include prefixes(transition, 0.8s);
        li {
          &:nth-of-type(1) {
            height: 200px;
            opacity: 1;
          }
          &:nth-of-type(2) {
            height: 225px;
            opacity: 1;
          }
          &:nth-of-type(3) {
            height: 210px;
            opacity: 1;
          }
        }
      }
    }
    a {
      margin: 150px 0 0 0;
    }
  }
  &__strauss {
    @extend %input;
    width: 200px;
    height: 300px;
    @include prefixes(transition, 0.8s);
    @include prefixes(transform,  translate(185px, -355px) rotate(-135deg));

    a {
      background: $TOGGLE2;
      span {
        @include prefixes(transform,  rotate(135deg));
      }
    }
    &:after {
      top: 250px;
      width: 1px;
      height: 0;
      background: $BORDER;
      left: 45px;
      @include prefixes(transition, 0.3s);
    }
    .list__straussItem {
      @include prefixes(transition, 0.8s);

      li {
        @extend %input;
        opacity: 0;
        width: 100px;
        height: 0;
        overflow: hidden;
        @include prefixes(transition, 0.8s);

        &:after {
          z-index: -1;
        }
        a {
          margin: 0 0 auto 0;
          background: $TOGGLE3;
        }
        &:after {
          top: 100px;
          left: 50px;
        }
        &:nth-of-type(1) {
          @include prefixes(transform,  scale(0.8) translate(-15px, -160px) rotate(-20deg));

          a {
            @include prefixes(transform,  rotate(155deg));
          }
        }
        &:nth-of-type(2) {
          font-size: 22px;
          @include prefixes(transform,  scale(0.8) translate(20px, -155px) rotate(30deg));

          a {
            @include prefixes(transform,  rotate(105deg));
          }
        }
        &:nth-of-type(3) {
          font-size: 22px;
          @include prefixes(transform, scale(0.8) translate(30px, -105px) rotate(120deg));

          &:after {
            top: 100px;
          }
          a {
            @include prefixes(transform, rotate(15deg));
          }
        }
      }
    }
    &:hover {
      opacity: 1;
      ul,
      li {
        display: flex;
        display: -webkit-box;
        display: -ms-flexbox;
        @include prefixes(align-items, center);
      }
      .list__straussItem {
        @include prefixes(transition, 0.8s);

        li {
          &:nth-of-type(1) {
            height: 200px;
            opacity: 1;
          }
          &:nth-of-type(2) {
            height: 230px;
            opacity: 1;
          }
          &:nth-of-type(3) {
            height: 225px;
            opacity: 1;
          }
        }
      }
    }
    a {
      margin: 150px 0 0 0;
    }
  }
  &__contact {
    @extend %input;
    height: 10px;
    overflow: hidden;
    @include prefixes(transition, 0.8s);
    @include prefixes(transform, translate(230px, -210px) rotate(135deg));

    a {
      background: $TOGGLE2;
      @include prefixes(transform, rotate(-135deg));
    }
  }
}

p {
  position: absolute;
  bottom: 10px;
  left: calc(50% - 22px);
  margin: 0;
  color: #fff;
  font-size: 30px;
}

.hum {
  position: absolute;
  top: 28px;
  left: 30px;
  width: 40px;
  height: 4px;
  background-color: #fff;
  border-radius: 4px;
  @include prefixes(transition, 0.8s);

  &:before {
    top: 10px;
    left: 0;
    width: 100%;
    height: 4px;
    background-color: #fff;
    border-radius: 4px;
    @include prefixes(transition, 0.8s);
  }
  &:after {
    top: 20px;
    left: 0;
    width: 100%;
    height: 4px;
    background-color: #fff;
    border-radius: 4px;
    @include prefixes(transition, 0.8s);
  }
}

@media screen and (min-width: 450px) {
  nav {
    @include prefixes(transform, scale(0.5));
  }
}

// base
html, body {
  width: 100%;
  height: 100%;
}

html {
  overflow: hidden;
}

body {
  position: relative;
  margin: 0;
  background-color: $BG;
  font-family: "Cute Font", Roboto, sans-serif;
  overflow: scroll;
  color: $FONT;
}

* {
  &:before,
  &:after {
    position: absolute;
    content: "";
  }
}

// （｀・ω・´）
// No images, just CSS.
// Chrome recommended.
// twitter.com/study_dedede