.menu-btn {
  position: fixed;
  top: 10px;
  right: 10px;
  display: flex;
  height: 50px;
  width: 50px;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  background-color: white;
}
.menu-btn:hover {
  cursor: pointer;
}

.menu-btn span,
.menu-btn span:before,
.menu-btn span:after {
  content: "";
  display: block;
  height: 3px;
  width: 25px;
  border-radius: 3px;
  background-color: #000; /* 3本線 */
  position: absolute;
}
.menu-btn span:before {
  bottom: 8px;
}
.menu-btn span:after {
  top: 8px;
}

#menu-btn-check {
  display: none;
}

#menu-btn-check:checked ~ .menu-btn span {
  background-color: rgba(
    255,
    255,
    255,
    0
  );
}


#menu-btn-check:checked ~ .menu-btn span::before {
  bottom: 0;
  transform: rotate(45deg);
}
#menu-btn-check:checked ~ .menu-btn span::after {
  top: 0;
  transform: rotate(-45deg);
}



.menu-content {
  width: 80%;
  height: 100%;
  position: fixed;
  top: 0;
  left: 100%;

  z-index: 998;
  background-color: white;
  transition: all 0.5s;
  opacity: 0.9;
}
.menu-content ul {
  padding: 70px 10px 0;
}
.menu-content ul li {
  border-bottom: solid 1px #000;
  list-style: none;
}
.menu-content ul li a {
  display: block;
  width: 100%;
  font-size: 15px;
  box-sizing: border-box;
  color: #000;
  text-decoration: none;
  padding: 9px 15px 10px 0;
  position: relative;
}

#menu-btn-check:checked ~ .menu-content {
  left: 30%;
}