html, body{
  width: 100%;
 }

body{ 
  width: 1000px;
  background-color: white;
  margin: 0 auto;
}

a{
  padding: 0 2em;
}

nav ul {
  display: flex;
  justify-content: flex-start;
  align-items: center;
  flex-wrap: wrap;
  list-style: none;
}

nav ul li {
  margin-right: 1rem;
}

nav ul li a {
  display: block;
  padding: 10px;
  color: #000000;
  text-decoration: none;
}

.menu .menu-bar a {
  position: relative;
  text-align: center;
  overflow: hidden;
  padding: 10px 55px;
}

.menu .menu-bar a::after {
  position: absolute;
  bottom: 0;
  left: 0;
  display: block;
  content: "";
  width: 0%;
  height: 2px;
  background: #F05152;
  transition: all 0.2s cubic-bezier(0.455, 0.03, 0.515, 0.955);
}

.menu .menu-bar a span {
  display: block;
  width: 100%;
  margin: 0 auto;
  transition: all 0.2s cubic-bezier(0.455, 0.03, 0.515, 0.955);
}

.menu .menu-bar a span.en {
  position: absolute;
  top: 100%;
  left: 0%;
  font-size: 14px;
  font-weight: bold;
  white-space: nowrap;
  color: #F05152;
}

.menu .menu-bar a:hover::after {
  width: 100%;
}

.menu .menu-bar a:hover span.ja {
  transform: translate(0%, -150%);
}

.menu .menu-bar a:hover span.en {
  top: 25%;
}