CodePen Embed - Pure CSS Menu

  <a href="https://front.codes/" class="logo" target="_blank">
    <img src="https://assets.codepen.io/1462889/fcy.png" alt="">
  </a>

    <input class="menu-icon" type="checkbox" id="menu-icon" name="menu-icon"/>
    <label for="menu-icon"></label>
    <nav class="nav">     
      <ul class="pt-5">
        <li><a href="#">Work</a></li>
        <li><a href="#">Studio</a></li>
        <li><a href="#">News</a></li>
        <li><a href="#">Contact</a></li>
      </ul>
    </nav>

    <div class="section-center">
      <h1 class="mb-0">Pure CSS Menu</h1>
    </div>



/* Please ❤ this if you like it! */


@import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@300;400;500;600;700;800;900&display=swap');

body{
  font-family: 'Montserrat', sans-serif;
  font-weight: 300;
  font-size: 15px;
  line-height: 1.7;
  color: #ececee;
  background-color: #1f2029;
  overflow: hidden;
  background-image: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/1462889/pat-back.svg');
  background-position: center;
  background-repeat: repeat;
  background-size: 4%;
  height: 100vh;
  width: 100%;
}
.section-center{
  position: absolute;
  top: 50%;
  left: 0;
  display: block;
  width: 100%;
  padding: 0;
  margin: 0;
  z-index: 6;
  text-align: center;
  transform: translateY(-50%);
}
h1{
  font-family: 'Montserrat', sans-serif;
  font-weight: 800;
  font-size: 7vw;
  line-height: 1;
  color: #ffeba7;
  text-align: center;
  -webkit-text-stroke: 2px #ffeba7;
  text-stroke: 2px #ffeba7;
  -webkit-text-fill-color: transparent;
  text-fill-color: transparent;
  color: transparent;
}

[type="checkbox"]:checked,
[type="checkbox"]:not(:checked){
  position: absolute;
  left: -9999px;
}
.menu-icon:checked + label,
.menu-icon:not(:checked) + label{
  position: fixed;
  top: 63px;
  right: 75px;
  display: block;
  width: 30px;
  height: 30px;
  padding: 0;
  margin: 0;
  cursor: pointer;
  z-index: 10;
}
.menu-icon:checked + label:before,
.menu-icon:not(:checked) + label:before{
  position: absolute;
  content: '';
  display: block;
  width: 30px;
  height: 20px;
  z-index: 20;
  top: 0;
  left: 0;
  border-top: 2px solid #ececee;
  border-bottom: 2px solid #ececee;
  transition: border-width 100ms 1500ms ease, 
              top 100ms 1600ms cubic-bezier(0.23, 1, 0.32, 1),
              height 100ms 1600ms cubic-bezier(0.23, 1, 0.32, 1), 
              background-color 200ms ease,
              transform 200ms cubic-bezier(0.23, 1, 0.32, 1);
}
.menu-icon:checked + label:after,
.menu-icon:not(:checked) + label:after{
  position: absolute;
  content: '';
  display: block;
  width: 22px;
  height: 2px;
  z-index: 20;
  top: 10px;
  right: 4px;
  background-color: #ececee;
  margin-top: -1px;
  transition: width 100ms 1750ms ease, 
              right 100ms 1750ms ease,
              margin-top 100ms ease, 
              transform 200ms cubic-bezier(0.23, 1, 0.32, 1);
}
.menu-icon:checked + label:before{
  top: 10px;
  transform: rotate(45deg);
  height: 2px;
  background-color: #ececee;
  border-width: 0;
  transition: border-width 100ms 340ms ease, 
              top 100ms 300ms cubic-bezier(0.23, 1, 0.32, 1),
              height 100ms 300ms cubic-bezier(0.23, 1, 0.32, 1), 
              background-color 200ms 500ms ease,
              transform 200ms 1700ms cubic-bezier(0.23, 1, 0.32, 1);
}
.menu-icon:checked + label:after{
  width: 30px;
  margin-top: 0;
  right: 0;
  transform: rotate(-45deg);
  transition: width 100ms ease,
              right 100ms ease,  
              margin-top 100ms 500ms ease, 
              transform 200ms 1700ms cubic-bezier(0.23, 1, 0.32, 1);
}

.nav{
  position: fixed;
  top: 33px;
  right: 50px;
  display: block;
  width: 80px;
  height: 80px;
  padding: 0;
  margin: 0;
  z-index: 9;
  overflow: hidden;
  box-shadow: 0 8px 30px 0 rgba(0,0,0,0.3);
  background-color: #353746;
  animation: border-transform 7s linear infinite;
  transition: top 350ms 1100ms cubic-bezier(0.23, 1, 0.32, 1),  
              right 350ms 1100ms cubic-bezier(0.23, 1, 0.32, 1),
              transform 250ms 1100ms ease,
              width 650ms 400ms cubic-bezier(0.23, 1, 0.32, 1),
              height 650ms 400ms cubic-bezier(0.23, 1, 0.32, 1);
}
@keyframes border-transform{
    0%,100% { border-radius: 63% 37% 54% 46% / 55% 48% 52% 45%; } 
  14% { border-radius: 40% 60% 54% 46% / 49% 60% 40% 51%; } 
  28% { border-radius: 54% 46% 38% 62% / 49% 70% 30% 51%; } 
  42% { border-radius: 61% 39% 55% 45% / 61% 38% 62% 39%; } 
  56% { border-radius: 61% 39% 67% 33% / 70% 50% 50% 30%; } 
  70% { border-radius: 50% 50% 34% 66% / 56% 68% 32% 44%; } 
  84% { border-radius: 46% 54% 50% 50% / 35% 61% 39% 65%; } 
}

.menu-icon:checked ~ .nav {
  animation-play-state: paused;
  top: 50%;
  right: 50%;
  transform: translate(50%, -50%);
  width: 200%;
  height: 200%;
  transition: top 350ms 700ms cubic-bezier(0.23, 1, 0.32, 1),  
              right 350ms 700ms cubic-bezier(0.23, 1, 0.32, 1),
              transform 250ms 700ms ease,
              width 750ms 1000ms cubic-bezier(0.23, 1, 0.32, 1),
              height 750ms 1000ms cubic-bezier(0.23, 1, 0.32, 1);
}

.nav ul{
  position: absolute;
  top: 50%;
  left: 0;
  display: block;
  width: 100%;
  padding: 0;
  margin: 0;
  z-index: 6;
  text-align: center;
  transform: translateY(-50%);
  list-style: none;
}
.nav ul li{
  position: relative;
  display: block;
  width: 100%;
  padding: 0;
  margin: 10px 0;
  text-align: center;
  list-style: none;
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transform: translateY(30px);
  transition: all 250ms linear;
}
.nav ul li:nth-child(1){
  transition-delay: 200ms;
}
.nav ul li:nth-child(2){
  transition-delay: 150ms;
}
.nav ul li:nth-child(3){
  transition-delay: 100ms;
}
.nav ul li:nth-child(4){
  transition-delay: 50ms;
}
.nav ul li a{
  font-family: 'Montserrat', sans-serif;
  font-size: 9vh;
  text-transform: uppercase;
  line-height: 1.2;
  font-weight: 800;
  display: inline-block;
  position: relative;
  color: #ececee;
  transition: all 250ms linear;
}
.nav ul li a:hover{
  text-decoration: none;
  color: #ffeba7;
}
.nav ul li a:after{
  display: block;
  position: absolute;
  top: 50%;
  content: '';
  height: 2vh;
  margin-top: -1vh;
  width: 0;
  left: 0;
  background-color: #353746;
  opacity: 0.8;
  transition: width 250ms linear;
}
.nav ul li a:hover:after{
  width: 100%;
}


.menu-icon:checked ~ .nav  ul li {
  pointer-events: auto;
  visibility: visible;
  opacity: 1;
  transform: translateY(0);
  transition: opacity 350ms ease,
              transform 250ms ease;
}
.menu-icon:checked ~ .nav ul li:nth-child(1){
  transition-delay: 1400ms;
}
.menu-icon:checked ~ .nav ul li:nth-child(2){
  transition-delay: 1480ms;
}
.menu-icon:checked ~ .nav ul li:nth-child(3){
  transition-delay: 1560ms;
}
.menu-icon:checked ~ .nav ul li:nth-child(4){
  transition-delay: 1640ms;
}



.logo {
  position: absolute;
  top: 60px;
  left: 50px;
  display: block;
  z-index: 11;
  transition: all 250ms linear;
}
.logo img {
  height: 26px;
  width: auto;
  display: block;
}



@media screen and (max-width: 991px) {
  .menu-icon:checked + label,
  .menu-icon:not(:checked) + label{
    right: 55px;
  }
  .logo {
    left: 30px;
  }
  .nav{
    right: 30px;
  }
  h1{
    font-size: 9vw;
    -webkit-text-stroke: 2px transparent;
    text-stroke: 2px transparent;
    -webkit-text-fill-color: #ffeba7;
    text-fill-color: #ffeba7;
    color: #ffeba7;
  }
  .nav ul li a{
    font-size: 8vh;
  }
}

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            BEST VIEWED FULLSCREEN
   https://codepen.io/ig_design/full/XWXZaGb
 * ========================================= */

This Pen is owned by Ivan Grozdic on CodePen.

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