/* ============================================
   Hero Section - "融雪见阳" 意境
   ============================================ */

.hero {
  position: relative;
  width: 100%;
  min-height: 62vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background-color: #0f0f13;
  /* 视差变量 */
  --parallax-x: 0px;
  --parallax-y: 0px;
}

/* --- 双背景层 --- */
.hero-bg-layer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  will-change: opacity, transform, filter;
}

/* 积雪图（默认）：常态清冽 */
.hero-bg-default {
  opacity: 1;
  transform: scale(1.05) translate(var(--parallax-x), var(--parallax-y));
  filter: brightness(0.95);
  z-index: 0;
  transition: opacity 3s cubic-bezier(0.4, 0, 0.2, 1),
              filter 3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 阳光图（悬停）：常态隐匿 */
.hero-bg-hover {
  opacity: 0;
  transform: scale(1.05) translate(calc(var(--parallax-x) * 0.5), calc(var(--parallax-y) * 0.5));
  filter: brightness(0.75);
  z-index: 1;
  transition: opacity 3.5s cubic-bezier(0.4, 0, 0.2, 1),
              filter 3.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 意境切换：积雪自然淡出过曝，阳光温柔浮现 */
.hero.is-hover .hero-bg-default {
  opacity: 0.12;
  filter: brightness(1.25) blur(1.5px);
}

.hero.is-hover .hero-bg-hover {
  opacity: 1;
  filter: brightness(1);
}

/* --- 阳光光晕：从画面上方洒落 --- */
.hero-sun-glow {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(
    ellipse 80% 60% at 50% 25%,
    rgba(255, 230, 180, 0.35) 0%,
    rgba(255, 210, 140, 0.15) 35%,
    transparent 70%
  );
  opacity: 0;
  z-index: 2;
  pointer-events: none;
  mix-blend-mode: screen;
  transition: opacity 2.5s ease-out 0.3s;
}

.hero.is-hover .hero-sun-glow {
  opacity: 1;
}

/* --- 暗角：聚焦中心 --- */
.hero-vignette {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(
    ellipse at center,
    transparent 0%,
    transparent 35%,
    rgba(0, 0, 0, 0.45) 100%
  );
  z-index: 3;
  pointer-events: none;
  transition: opacity 2.5s ease;
}

/* 阳光出现时暗角减弱，画面更开阔 */
.hero.is-hover .hero-vignette {
  opacity: 0.55;
}

/* --- 渐变遮罩：确保文字可读 --- */
.hero-gradient-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    to bottom,
    rgba(15, 15, 19, 0.55) 0%,
    rgba(15, 15, 19, 0.2) 50%,
    rgba(15, 15, 19, 0.65) 100%
  );
  z-index: 4;
  pointer-events: none;
  transition: background 2.5s ease;
}

/* 阳光模式下遮罩变亮、变暖 */
.hero.is-hover .hero-gradient-overlay {
  background: linear-gradient(
    to bottom,
    rgba(15, 15, 19, 0.35) 0%,
    rgba(15, 15, 19, 0.1) 50%,
    rgba(15, 15, 19, 0.45) 100%
  );
}

/* --- 饥荒风格颗粒感纹理 --- */
.hero-grain {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.03;
  z-index: 5;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
}

/* --- 内容层 --- */
.hero-content {
  position: relative;
  z-index: 10;
  text-align: center;
  padding: 2rem;
  max-width: 700px;
  margin: 0 auto;
  color: #ffffff;
  text-shadow: 0 2px 4px rgba(0,0,0,0.5);
}

.hero-title {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: 1px;
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.8s ease forwards;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: #e0e0e0;
  margin-bottom: 2rem;
  line-height: 1.6;
  letter-spacing: 2px;
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.8s ease 0.2s forwards;
}

.hero-btn {
  display: inline-block;
  padding: 12px 36px;
  background: #fff;
  color: var(--accent-fire);
  font-size: 16px;
  font-weight: 600;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.8s ease 0.4s forwards;
  transition: all var(--transition-normal);
}

.hero-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.18);
  background: var(--accent-fire);
  color: #fff;
}

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* --- 移动端无 hover 时的兜底展示 --- */
@media (hover: none) and (pointer: coarse) {
  .hero-bg-default {
    opacity: 0.12;
    filter: brightness(1.25) blur(1.5px);
    transform: scale(1.05);
  }
  .hero-bg-hover {
    opacity: 1;
    filter: brightness(1);
    transform: scale(1.05);
  }
  .hero-sun-glow {
    opacity: 1;
  }
  .hero-vignette {
    opacity: 0.55;
  }
  .hero-gradient-overlay {
    background: linear-gradient(
      to bottom,
      rgba(15, 15, 19, 0.35) 0%,
      rgba(15, 15, 19, 0.1) 50%,
      rgba(15, 15, 19, 0.45) 100%
    );
  }
}