/* 内容区域使用flex-grow填充剩余空间 */
.content {
  background-color: #b51c1c;
  background-image: url('img/index-bg.png');
  background-size: cover;
  background-position: center;
  /* 如果页面有输入框，建议改用`position: fixed`布局*/
}

.content .letter-title {
  margin-top: -10.5vw;
  margin-bottom: 3.2vw;
}

.content .letter-title h2 {
  font-size: 6vw;
  line-height: 1.5;
  color: #f5051b;
  font-weight: 600;
}

.content .letter-text {
  text-align: center;
}

.content .letter-text p {
  font-size: 3.8vw;
  line-height: 1.6;
  color: #333;
}

.content .letter-text p.special {
  font-size: 4.23333vw;
  color: #f5051b;
}

/* 底部气球容器样式 */
.balloons-container {
  position: absolute;
  bottom: 28vw;
  left: 50%;
  transform: translateX(-50%);
  width: 80vw;
  height: 50vw;
  max-width: 160vw;
  max-height: 80vw;
  z-index: 2000;
  /* 半弧形排列的气球位置 */
}

.balloons-container .balloon {
  position: absolute;
  width: 10.6667vw;
  height: 10.6667vw;
  max-width: 21.3333vw;
  max-height: 21.3333vw;
  border-radius: 50%;
  background-color: rgba(255, 107, 107, 0.8);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  cursor: pointer;
  animation: float 3s ease-in-out infinite;
  transform-origin: bottom center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  z-index: 2000;
}

.balloons-container .balloon a {
  font-size: 5vw;
  text-decoration: none;
  color: #fff;
  display: block;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
}

.balloons-container .balloon:hover,
.balloons-container .balloon:focus {
  transform: rotate(var(--rotation)) scale(1.2);
  box-shadow: 0 0 10px rgba(255, 255, 200, 0.8), 0 0 20px rgba(255, 255, 200, 0.6), 0 0 30px rgba(255, 255, 200, 0.4), 0 0 40px rgba(255, 255, 200, 0.2);
}

.balloons-container .balloon:hover a,
.balloons-container .balloon:focus a {
  transform: scale(1.2);
  transition: transform 0.3s ease;
}

.balloons-container .balloon-1 {
  bottom: 0;
  left: 10%;
  background-color: rgba(255, 107, 107, 0.8);
  --rotation: -60deg;
  animation-delay: 0s;
  z-index: 2000;
}

.balloons-container .balloon-2 {
  bottom: 8vw;
  left: 19%;
  background-color: rgba(78, 205, 196, 0.8);
  --rotation: -30deg;
  animation-delay: 0.5s;
  z-index: 2000;
}

.balloons-container .balloon-3 {
  bottom: 10vw;
  left: 35%;
  background-color: rgba(69, 183, 209, 0.8);
  --rotation: 0deg;
  animation-delay: 1s;
  z-index: 2000;
}

.balloons-container .balloon-4 {
  bottom: 10vw;
  right: 35%;
  background-color: rgba(150, 206, 180, 0.8);
  --rotation: 0deg;
  animation-delay: 1.5s;
  z-index: 2000;
}

.balloons-container .balloon-5 {
  bottom: 9vw;
  right: 19%;
  background-color: rgba(255, 234, 167, 0.8);
  --rotation: 30deg;
  animation-delay: 2s;
  z-index: 2000;
}

.balloons-container .balloon-6 {
  bottom: 0;
  right: 10%;
  background-color: rgba(218, 160, 221, 0.8);
  --rotation: 60deg;
  animation-delay: 2.5s;
  z-index: 2000;
}

/* 浮动动画定义 */
@keyframes float {

  0%,
  100% {
    transform: rotate(var(--rotation)) translateY(0);
  }

  50% {
    transform: rotate(var(--rotation)) translateY(-2vw);
  }
}

/* 音乐控制按钮样式 */
.music-control {
  position: absolute;
  top: 5.3333vw;
  right: 5.3333vw;
  width: 11.7333vw;
  height: 11.7333vw;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.5);
  color: white;
  font-size: 5.3333vw;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  z-index: 9999;
  user-select: none;
  transition: all 0.3s ease;
  animation: rotate 2s linear infinite;
}

@keyframes rotate {
  0% {
    transform: rotate(0deg);
  }

  100% {
    transform: rotate(360deg);
  }
}

.music-control:hover {
  background-color: rgba(255, 255, 255, 0.7);
  transform: scale(1.1);
}

.music-control.paused {
  background-color: rgba(255, 255, 255, 0.3);
}