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

body {
  font-family: 'Arial', sans-serif;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0;
  padding: 0;
  overflow: hidden;
  position: relative;
  background: #0d1117;
}

.background-gradient {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(
    circle at center,
    rgba(255, 105, 180, 0.1) 0%,
    rgba(138, 43, 226, 0.05) 30%,
    rgba(13, 17, 23, 1) 70%
  );
  z-index: -1;
}

.container {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100vw;
  height: 100vh;
  z-index: 1;
  position: relative;
}

.love-message {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 4rem;
  font-weight: bold;
  min-height: 120px;
  position: relative;
  width: 600px;
  margin-bottom: 40px;
  user-select: none;
}

.border-left,
.border-right {
  font-size: 5rem;
  font-weight: bold;
  color: white;
  text-shadow: 0 0 20px rgba(255, 255, 255, 0.8),
    0 0 40px rgba(255, 255, 255, 0.4);
  cursor: grab;
  user-select: none;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  transition: all 0.2s ease;
  z-index: 10;
}

.border-left:active,
.border-right:active {
  cursor: grabbing;
  transform: translateY(-50%) scale(1.1);
  text-shadow: 0 0 30px rgba(255, 255, 255, 1),
    0 0 50px rgba(255, 255, 255, 0.6);
}

.border-left {
  left: -10px;
}

.border-right {
  right: -10px;
}

.message {
  color: #ff69b4;
  text-shadow: 0 0 20px rgba(255, 105, 180, 0.8),
    0 0 40px rgba(255, 105, 180, 0.4);
  white-space: nowrap;
  display: flex;
  justify-content: center;
  align-items: center;
  user-select: none;
  font-size: 4rem;
  position: relative;
  z-index: 5;
  transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.instruction {
  color: rgba(255, 255, 255, 0.6);
  font-size: 1.2rem;
  text-align: center;
  animation: fadeInOut 3s ease-in-out infinite;
}

.instruction p {
  margin: 0;
}

/* レスポンシブデザイン - 削除（下部で統一） */

/* アニメーション効果 */
@keyframes heartbeat {
  0% {
    transform: scale(1);
    text-shadow: 0 0 20px rgba(255, 23, 68, 0.8),
      0 0 40px rgba(255, 23, 68, 0.6);
  }
  50% {
    transform: scale(1.1);
    text-shadow: 0 0 30px rgba(255, 23, 68, 1), 0 0 50px rgba(255, 23, 68, 0.8);
  }
  100% {
    transform: scale(1);
    text-shadow: 0 0 20px rgba(255, 23, 68, 0.8),
      0 0 40px rgba(255, 23, 68, 0.6);
  }
}

@keyframes fadeInOut {
  0%,
  100% {
    opacity: 0.4;
  }
  50% {
    opacity: 0.8;
  }
}

@keyframes scaleIn {
  0% {
    transform: scale(0.9);
    opacity: 0.7;
  }
  50% {
    transform: scale(1.05);
    opacity: 0.9;
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}

.message-changing {
  animation: scaleIn 0.4s ease-out;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
  .container {
    padding: 0 20px;
  }

  .love-message {
    font-size: 3rem;
    width: calc(100vw - 80px);
    max-width: 400px;
  }

  .border-left,
  .border-right {
    font-size: 4rem;
  }

  .message {
    font-size: 3rem;
  }

  .instruction {
    font-size: 1rem;
    padding: 0 20px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 15px;
  }

  .love-message {
    font-size: 2.5rem;
    width: calc(100vw - 60px);
    max-width: 300px;
    min-height: 80px;
  }

  .border-left,
  .border-right {
    font-size: 3rem;
  }

  .message {
    font-size: 2.5rem;
  }

  .instruction {
    font-size: 0.9rem;
    padding: 0 15px;
  }
}

@media (max-width: 360px) {
  .container {
    padding: 0 10px;
  }

  .love-message {
    font-size: 2rem;
    width: calc(100vw - 40px);
    max-width: 280px;
    min-height: 70px;
  }

  .border-left,
  .border-right {
    font-size: 2.5rem;
  }

  .message {
    font-size: 2rem;
  }

  .instruction {
    font-size: 0.8rem;
    padding: 0 10px;
  }
}