#intro {
  display: block;
  position: fixed;
  height: 100%;
  width: 100%;
  z-index: 5;
  background: var(--bg-intro-color);
  transition: opacity 550ms ease-in-out;
}

#intro .container {
  height: calc(100vh - var(--main-diff) * 2);
}

#intro .about {
  position: absolute;
  right: 0;
}

#intro #page-index {
  position: absolute;
  bottom: 0;
}

.language {
  display: flex;
  gap: 1em;
}

#intro .language {
  position: absolute;
  bottom: 0;
  right: 0;
}

.language a{
  font-size: 24px;
}

/* next button */
#intro #nextButton,
#modal-date-btn {
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translate(-50%, 0);
  text-align: center;
  background: transparent;
  color: var(--white-color);
  border: var(--button-border-stroke) solid var(--white-color);
  border-radius: var(--button-border-radius);
  padding: 30px 60px;
  box-sizing: border-box;
}

/* TEXT */
#intro #startText {
  width: 60%;
}

#intro #explainText {
  display: none;
  width: 60%;
}

#intro #controlText {
  display: none;
  flex-direction: column;
  align-items: center;
  width: 100%;
}

#intro #controlText div {
  display: flex;
  flex-direction: row;
  align-items: center;
  padding: 1rem;
}

#intro .center-intro {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  line-height: 1.5em;
}

/* ANIMATION */
#startText,
#explainText,
.controlText {
  opacity: 0;
}