/* 季节背景基类 */
.season-bg {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -2;
  transition: background 1.5s ease;
}

/* 春季 - 3-5月 */
.season-spring {
  background: linear-gradient(135deg, 
    rgba(255, 245, 245, 0.95) 0%,
    rgba(255, 250, 240, 0.9) 25%,
    rgba(240, 255, 240, 0.85) 50%,
    rgba(240, 248, 255, 0.9) 75%,
    rgba(255, 245, 238, 0.95) 100%
  );
}

/* 夏季 - 6-8月 */
.season-summer {
  background: linear-gradient(135deg,
    rgba(224, 247, 255, 0.95) 0%,
    rgba(240, 255, 240, 0.9) 25%,
    rgba(255, 250, 205, 0.85) 50%,
    rgba(255, 245, 238, 0.9) 75%,
    rgba(240, 248, 255, 0.95) 100%
  );
}

/* 秋季 - 9-11月 */
.season-autumn {
  background: linear-gradient(135deg,
    rgba(255, 250, 240, 0.95) 0%,
    rgba(255, 245, 238, 0.9) 25%,
    rgba(255, 240, 230, 0.85) 50%,
    rgba(255, 235, 220, 0.9) 75%,
    rgba(255, 230, 210, 0.95) 100%
  );
}

/* 冬季 - 12-2月 */
.season-winter {
  background: linear-gradient(135deg,
    rgba(240, 248, 255, 0.95) 0%,
    rgba(224, 247, 255, 0.9) 25%,
    rgba(240, 255, 255, 0.85) 50%,
    rgba(248, 248, 255, 0.9) 75%,
    rgba(240, 248, 255, 0.95) 100%
  );
}

/* 粒子效果 */
.particles {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  pointer-events: none;
}

.particle {
  position: absolute;
  border-radius: 50%;
  opacity: 0.2;
  animation: float 15s infinite linear;
}

/* 季节特色粒子 */
.spring-particle {
  background: radial-gradient(circle, rgba(255, 182, 193, 0.3), rgba(144, 238, 144, 0.2));
  box-shadow: 0 0 10px rgba(144, 238, 144, 0.3);
}

.summer-particle {
  background: radial-gradient(circle, rgba(173, 216, 230, 0.3), rgba(144, 238, 144, 0.2));
  box-shadow: 0 0 15px rgba(173, 216, 230, 0.3);
}

.autumn-particle {
  background: radial-gradient(circle, rgba(255, 215, 0, 0.2), rgba(210, 105, 30, 0.2));
  box-shadow: 0 0 12px rgba(255, 140, 0, 0.2);
}

.winter-particle {
  background: radial-gradient(circle, rgba(173, 216, 230, 0.3), rgba(240, 255, 255, 0.3));
  box-shadow: 0 0 20px rgba(240, 255, 255, 0.4);
}

/* 飘动动画 */
@keyframes float {
  0%, 100% {
    transform: translate(0, 0) rotate(0deg);
  }
  25% {
    transform: translate(20px, 40px) rotate(90deg);
  }
  50% {
    transform: translate(40px, 20px) rotate(180deg);
  }
  75% {
    transform: translate(20px, 0) rotate(270deg);
  }
}

/* 季节标志 */
.season-icon {
  position: fixed;
  font-size: 24px;
  opacity: 0.1;
  z-index: -1;
  animation: gentle-float 20s infinite ease-in-out;
}

/* 季节标志颜色 */
.spring-icon { color: #ff6b9d; }
.summer-icon { color: #4ecdc4; }
.autumn-icon { color: #ff9f43; }
.winter-icon { color: #74b9ff; }

@keyframes gentle-float {
  0%, 100% {
    transform: translateY(0) rotate(0deg);
  }
  33% {
    transform: translateY(-20px) rotate(120deg);
  }
  66% {
    transform: translateY(10px) rotate(240deg);
  }
}