body {
  font-family: sans-serif;
  margin: 0;
}
.section {
  height: 100vh;
  background-color: #7b1fa2;
  display: flex;
  justify-content: center;
  align-items: center;
}
.menu-btn {
  display: block;
  width: 50px;
  height: 50px;
  background-color: #fff;
  border-radius: 50%;
  position: relative;
}
/*-----------------сам бургер формируем---------------------*/
.menu-btn span,
.menu-btn span::before,
.menu-btn span::after {
  position: absolute;
  top: 50%; margin-top: -1px;
  left: 50%; margin-left: -10px;
  width: 20px;
  height: 2px;
  background-color: #222;
}
.menu-btn span::before,
.menu-btn span::after {
  content: '';
  display: block;
  transition: 0.2s;
}

/*----------------------"рассталкиваем" полоски друг от друга на 5 px*/ 
.menu-btn span::before {
  transform: translateY(-5px);
}
.menu-btn span::after {
  transform: translateY(5px);
}
/*--------------формируем стрелку при наведении на кнопку "мышки"*/
.menu-btn_active span:before {
  transform: rotate(-35deg);
  width: 10px;
  transform-origin: left bottom;
}
.menu-btn_active span:after {
  transform: rotate(35deg);
  width: 10px;
  transform-origin: left top;
}

/*--------------end burger------------------------------------------------*/
.menu-block {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}
.menu-nav a {
  text-decoration: none;
  color: #222;
  text-transform: uppercase;
  font-weight: 100;
  display: inline-block;
  margin-right: 20px;
  transition: 1s;
}
.menu-nav {
  transition: 0.2s;
  transform: scaleX(0) translateX(0%);
  transform-origin: right center;
  opacity: 0;
  visibility: hidden;
  height: 50px;
  line-height: 50px;
  background-color: #fff;
  padding-right: 25px;
  padding-left: 25px;
  margin-right: -25px;
  border-top-left-radius: 50px;
  border-bottom-left-radius: 50px;
}
.menu-nav_active {
  transform: scaleX(1) translateX(0%);
  opacity: 1;
  visibility: visible;
}