CodePen Embed - Mobile Menu Animation

<div class="page">
  <span class="page__name">Mobile Menu Animation</span>
  <span class="page__hint">
    Push the button below to see the animation
  </span>
</div>
<div class="menu">
  <nav class="menu__nav">
    <ul class="menu__list r-list">
      <li class="menu__group">
        <a href="#0" class="menu__link r-link">Home</a>
      </li>
      <li class="menu__group">
        <a href="#0" class="menu__link r-link">About me</a>
      </li>
      <li class="menu__group">
        <a href="#0" class="menu__link r-link">Services</a>
      </li>
      <li class="menu__group">
        <a href="#0" class="menu__link r-link">Portfolio</a>
      </li>
      <li class="menu__group">
        <a href="#0" class="menu__link r-link">Blog</a>
      </li>
      <li class="menu__group">
        <a href="#0" class="menu__link r-link">Contacts</a>
      </li>
    </ul>
  </nav>
  <button class="menu__toggle r-button" type="button">
    <span class="menu__hamburger m-hamburger">
      <span class="m-hamburger__label">
        <span class="menu__toggle-hint screen-reader">Open menu</span>
      </span>
    </span>
  </button>
</div>
<div class="linktr">
  <a href="https://cssisntmagic.substack.com" target="_blank" class="linktr__goal r-link">Subscribe on my email newsletter with CSS tips 💪💪💪</a>
</div>

/*
!!! This demo is being refactored !!!

-- add auto focus on the first item of the navigation when it is shown
-- replace .menu:not(.menu_activated) .menu__list{  display: none; } to hidden
-- use :is pseudo-class to simplify selectors 

*/
/*
=====
DEPENDENCES
=====
*/

/* The component will reset button browser styles */

.r-button{
  --uirButtonBackgroundColor: var(--rButtonBackgroundColor, transparent);
  --uirButtonPadding: var(--rButtonPadding, var(--rButtonPaddingTop, 0) var(--rButtonPaddingRight, 0) var(--rButtonPaddingBottom, 0) var(--rButtonPaddingLeft, 0));
  --uirButtonBorderWidth: var(--rButtonBorderWidth, 0);
  --uirButtonBorderStyle: var(--rButtonBorderStyle, solid);
  --uirButtonBorderColor: var(--rButtonBorderColor, currentColor);
  --uirButtonFontFamily: var(--rButtonFontFamily, inherit);
  --uirButtonFontSize: var(--rButtonFontSize,  inherit);
  --uirButtonColor: var(--rButtonColor);

  background-color: var(--uirButtonBackgroundColor);
  padding: var(--uirButtonPadding);

  border-width: var(--uirButtonBorderWidth);
  border-style: var(--uirButtonBorderStyle);
  border-color: var(--uirButtonBorderColor);

  cursor: pointer;

  font-family: var(--uirButtonFontFamily);
  font-size: var(--uirButtonFontSize);
}

.r-button::-moz-focus-inner,
.r-button[type="button"]::-moz-focus-inner,
.r-button[type="reset"]::-moz-focus-inner,
.r-button[type="submit"]::-moz-focus-inner {
  
  /* Remove the inner border and padding in Firefox. */
  
  border-style: none;
  padding: 0;
}

/* The component will reset browser's styles of link */

.r-link{
    --uirLinkDisplay: var(--rLinkDisplay, inline-flex);
    --uirLinkTextColor: var(--rLinkTextColor);
    --uirLinkTextDecoration: var(--rLinkTextDecoration, none);

    display: var(--uirLinkDisplay) !important;
    color: var(--uirLinkTextColor) !important;
    text-decoration: var(--uirLinkTextDecoration) !important;
}

/* The component will reset browser's styles of list */

.r-list{
    --uirListPaddingLeft: var(--rListPaddingLeft, 0);
    --uirListMarginTop: var(--rListMarginTop, 0);
    --uirListMarginBottom: var(--rListMarginBottom, 0);
    --uirListListStyle: var(--rListListStyle, none);

    padding-left: var(--uirListPaddingLeft) !important;
    margin-top: var(--uirListMarginTop) !important;
    margin-bottom: var(--uirListMarginBottom) !important;
    list-style: var(--uirListListStyle) !important;
}

/* Basic styles of the hamburger component */

.m-hamburger{  
  --uiHamburgerThickness: var(--hamburgerThickness, 4px);

  display: var(--hamburgerDisplay, inline-flex);
  width: var(--hamburgerWidth, 28px);
  height: var(--hamburgerHeight, 20px);

  position: relative;
}

.m-hamburger::before, 
.m-hamburger::after, 
.m-hamburger__label{
  width: 100%;
  height: var(--uiHamburgerThickness);
  border-radius: var(--hamburgerBorderRadius, 5px);
  background-color: var(--hamburgerBackgroundColor, currentColor);

  position: absolute;
  left: 0;
}

.m-hamburger::before, 
.m-hamburger::after{
  content:"";
}

.m-hamburger::before{
  top: 0;
}

.m-hamburger::after{
  bottom: 0;
}

.m-hamburger__label{
  /* The calculation of middle hamburger button line position */
  
  top: calc(50% - calc(var(--uiHamburgerThickness) / 2));
}

/* helper to hide elements that are available only for screen readers. */

.screen-reader{
  width: var(--screenReaderWidth, 1px) !important;
  height: var(--screenReaderHeight, 1px) !important;
  padding: var(--screenReaderPadding, 0) !important;
  border: var(--screenReaderBorder, none) !important;

  position: var(--screenReaderPosition, absolute) !important;
  clip: var(--screenReaderClip, rect(1px, 1px, 1px, 1px)) !important;
  overflow: var(--screenReaderOverflow, hidden) !important;
}

/*
=====
MENU STYLES
=====
*/

.menu{
  --uiMenuCircleSize: var(--menuCircleSize, 6.25rem);
  --uiMenuCircleOffset: var(--menuCircleOffset, 1rem);
  --uiMenuCircleHeight: calc(var(--uiMenuCircleSize) / 2);  
  --uiMenuCircleBackgroundColor: var(--menuCircleBackgroundColor, currentColor);

  --uiMenuHamburgerWidth: var(--menuHamburgerWidth, 1.75rem);
  --uiMenuHamburgerHeight: var(--menuHamburgerHeight, 1.25rem);
  
  --rButtonPaddingTop: calc(var(--uiMenuCircleHeight) - var(--uiMenuHamburgerHeight) - var(--uiMenuCircleOffset));
  
  --hamburgerWidth: var(--uiMenuHamburgerWidth);
  --hamburgerHeight: var(--uiMenuHamburgerHeight);
  --hamburgerBackgroundColor: var(--menuHamburgerBackgroundColor, #fff);

  width: 100%;
  
  display: flex;
  flex-direction: column;
  align-items: center;  

  position: fixed;
  bottom: 0;
  left: 0;
  z-index: var(--menuZindex, 9998);
}

.menu__nav{
  box-sizing: border-box;
  width: 100%;
  height: 0;

  transition: opacity .2s ease-out;
  opacity: 0;

  display: flex;
  align-items: flex-end;
  z-index: 2;
}

.menu__list{
  width: 100%;
  max-height: 100%;

  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

.menu__toggle{
  box-sizing: border-box;
  width: var(--uiMenuCircleSize);
  height: var(--uiMenuCircleHeight);
  flex: none;

  position: relative;
}

.menu__toggle::before{
  /*
  1. The font-size property is used to simplify calculations of the element's sizes and position
  2. The negative value for the bottom property need for hiding half of circle. 
  */

  content: "";
  width: 1em;
  height: 1em;
  font-size: var(--uiMenuCircleSize); /* 1 */

  background-color: var(--uiMenuCircleBackgroundColor);
  border-radius: 50%;

  position: absolute;
  bottom: -.5em; /* 2 */
  left: calc(50% - .5em);
  z-index: -1;

  will-change: width, height;
  transition: transform .25s cubic-bezier(0.04, -0.1, 0.29, 0.98),
              width .25s cubic-bezier(0.04, -0.1, 0.29, 0.98),
              height .25s cubic-bezier(0.04, -0.1, 0.29, 0.98);
}

/* styles of hamburger's animation */

.m-hamburger::before, 
.m-hamburger::after, 
.m-hamburger__label{
  transition-timing-function: ease;
  transition-duration: .15s;  
}

.m-hamburger::before, 
.m-hamburger::after{
  transition-property: transform;
}

.m-hamburger__label{
  transition-property: transform, opacity;
}

/*
=====
MENU STATES
=====
*/

.menu__toggle:focus{
  outline: var(--menuHaburgerOutlineOWidth, 2px) solid var(--menuHaburgerOutlineColor);
  outline-offset: var(--menuHaburgerOutlineOffset, 5px);
}

.menu_activated{
  height: 100%;
}

.menu_activated .menu__nav{
  flex-grow: 1;
  opacity: 1;

  will-change: opacity;
  transition-duration: .2s;
  transition-delay: .3s;
}

.menu_activated .menu__toggle::before{
  width: 100vmax;
  height: 100vmax;
  transform: translate3d(-50vh, -50vh, 0) scale(5);
  transition-duration: 1s;
}

.menu:not(.menu_activated) .menu__list{
  display: none;
}

.menu_activated .m-hamburger::before{
  top: 50%;
  transform: translate3d(0, -50%, 0) rotate(45deg);
}

.menu_activated .m-hamburger::after{
  transform: translate3d(0, -50%, 0) rotate(135deg);
  top: 50%;
}

.menu_activated .m-hamburger__label{
  transform: rotate(-45deg) translate3d(-.285em,-.3em, 0);
  opacity: 0;
}

/*
=====
SETTINGS
=====
*/

:root{
  --colorWhite: #fff;
  --colorMain: #4557bb;
  --menuCircleBackgroundColor: var(--colorMain);
  --menuHamburgerBackgroundColor: var(--colorWhite);
  --menuHaburgerOutlineColor: var(--colorMain);
}

.menu_activated{
  --menuHaburgerOutlineColor: var(--colorWhite);
}

/*
=====
DEMO
=====
*/

body{
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  margin: 0;  
  font-family: -apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Open Sans, Ubuntu, Fira Sans, Helvetica Neue, sans-serif;
  font-size: 1rem;
}

.page{
  max-width: 380px;
  padding: 1rem;
  margin: auto;  
  text-align: center;
}

.page__name{
  display: block;
  font-size: 2rem;
  font-weight: 700;
}

.page__hint{
  display: block;
  line-height: 1.45;
  margin-top: 1rem;
}

.menu__group{
  --rLinkTextColor: var(--colorWhite);

  padding: .5rem 2rem; 
  font-size: 2rem;
  font-weight: 700;
  text-transform: uppercase;
}

.linktr{
  order: -1;
  padding: 1.75rem;
  text-align: center;
}

.linktr__goal{
  background-color: rgb(209, 246, 255);
  color: rgb(8, 49, 112);
  box-shadow: rgb(8 49 112 / 24%) 0px 2px 8px 0px;
  border-radius: 2rem;
  padding: .5rem 1.25rem;
}

@media (min-width: 1024px){
  
  .linktr{
    position: absolute; 
    right: 1rem; 
    bottom: 1rem;
  }
}

/*
!!!!!
This code is created to display element's behavior. I'm not a JS expert so don't use it
!!!!!
*/


(function(){
  'use strict';

  class Menu {
    constructor(settings) {
      this.menuRootNode = settings.menuRootNode;
      this.isOpened = false;
    }
    
    changeMenuState(menuState) {
      return this.isOpened = !menuState;
    }
    
    changeToggleHint(toggleHint, toggleNode) {
      toggleNode.textContent = toggleHint;
      return toggleHint; 
    }
  }

  const menuClassesNames = {
    rootClass: 'menu',
    activeClass: 'menu_activated',
    toggleClass: 'menu__toggle',
    toggleHintClass: 'menu__toggle-hint'
  }
  
  const jsMenuNode = document.querySelector(`.${menuClassesNames.rootClass}`);
  const demoMenu = new Menu ({
    menuRootNode: jsMenuNode
  });
  
  function getCurrentToggleHint(currentMenuState) {
    return (currentMenuState !== true) ? 'Open menu' : 'Close menu';
  }
  
  function toggleMenu(event) {
    
      let currentMenuState = demoMenu.changeMenuState(demoMenu.isOpened);
      let toggleHint = getCurrentToggleHint(currentMenuState);
      
      demoMenu.changeToggleHint(
        toggleHint, 
        demoMenu.menuRootNode.querySelector(`.${menuClassesNames.toggleHintClass}`)
      );
      demoMenu.menuRootNode.classList.toggle(`${menuClassesNames.activeClass}`);
      
      return currentMenuState;  
  }
  
  jsMenuNode.querySelector(`.${menuClassesNames.toggleClass}`).addEventListener('click', toggleMenu);
})();

Run Pen

This Pen is owned by Stas Melnikov on CodePen.

See more by @melnik909 on CodePen

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.