* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body, html {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: black;
  font-family: sans-serif;
}

#title-screen {
  width: 100vw;
  height: 100vh;
  background-image: url("assets/title_background.png");
  background-size: cover;
  background-position: center;
  display: flex;
  justify-content: center;
  align-items: flex-end;
  position: relative;
  z-index: 0;
}

#start-button {
  width: 300px;
  margin-bottom: 200px;
  cursor: pointer;
  z-index: 10;
}

.pulsing {
  animation: pulse 1.2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1); }
}

#fade-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: black;
  opacity: 0;
  pointer-events: none;
  transition: opacity 1s ease;
  z-index: 1000;
}

#icon-wrapper {
  position: absolute;
  top: 10%;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  z-index: 1000;
}

.icon {
  width: 35vw; /* 必要に応じて調整 */
  height: auto;
  transform: translateX(100vw);
  opacity: 0.8;
  transition: transform 0.5s ease, opacity 0.5s ease;
}

.icon.visible {
  transform: translateX(0);
  opacity: 0.5;
}

.icon.hidden {
  opacity: 0;
  transform: translateX(100vw); /* 明示的に指定しておくと安定 */
}

.blinking {
  animation: blink 0.05s steps(1, start) infinite;  /* ← 点滅速度を高速化 */
}

#tutorial-img {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  max-width: 90vw;
  max-height: 90vh;
  z-index: 100;
  cursor: pointer;
  opacity: 0;           /* ← display:none の代わりに透明にしておく */
  transition: opacity 1s ease;
}
#tutorial-img.visible {
  opacity: 1;           /* ← JSで表示する時はこのクラスを付ける */
}
#tutorial-img.fade-out {
  opacity: 0;
  transition: opacity 1s ease;
}


@keyframes blink {
  0% { opacity: 1; }
  50% { opacity: 0; }
  100% { opacity: 1; }
}