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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: #fafafa;
  color: #333;
  line-height: 1.6;
}

.container {
  max-width: 100%;
  padding: 15px;
}

.header {
  text-align: center;
  padding: 20px 0;
  margin-bottom: 20px;
  border-bottom: 1px solid #eee;
}

.title {
  font-size: 1.5rem;
  font-weight: 600;
  color: #1e1e1e;
}

#setu-title {
  display: block !important;
  text-align: left !important;
  width: 100% !important; 
  max-width: min(92vw, 700px);
  margin: 15px auto 25px !important; 
  background-color: #f2f4f6 !important; 
  border-radius: 999px !important;
  padding: 12px 25px 12px 35px !important;
  font-size: 15px;
  font-weight: 500;
  color: #4a5568; 
  line-height: 1.6;
  border: none;
  box-sizing: border-box;
  word-wrap: break-word;
}

.image-grid {
  display: flex;
  flex-direction: column;
  gap: 18px;
  width: 100%;
  max-width: min(90vw, 700px);
  margin: 0 auto;
}

.image-item {
  border-radius: 6px;
  overflow: hidden;
  box-shadow: 0 3px 10px rgba(0, 0, 0, .06);
  background: #f0f2f5;
  position: relative;
}

.img-wrap {
  position: relative;
  width: 100%;
  min-height: 180px;
  background: #f3f4f6; 
  overflow: hidden;
}

.img-wrap::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, #f3f4f6 0%, #e9eef6 50%, #f3f4f6 100%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite ease-in-out;
  z-index: 1;
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.img-wrap img {
  width: 100%;
  height: auto;
  display: block;
  opacity: 0;
  transition: opacity 0.5s ease;
  z-index: 2;
  object-fit: contain;
  position: relative;
}

.img-wrap.loaded::before {
  opacity: 0;
  transition: opacity 0.5s ease;
}

.img-wrap.loaded img {
  opacity: 1;
}

.explanation {
  background: linear-gradient(135deg, #f2f4f6, #eceef0);
  border: 1px solid #dde2e9;
  border-radius: 16px;
  padding: 22px;
  text-align: center;
  color: #4a5568;
  margin: 25px 0;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.12);
}

.explanation h2 {
  font-size: 20px;
  color: #2d2d2d;
  margin-bottom: 10px;
  font-weight: 600;
}

.explanation p {
  font-size: 15px;
  color: #506070;
}

.explanation p span {
  color: #2d3748;
  font-weight: 700;
  text-shadow: 0 0 8px rgba(45, 55, 72, 0.3);
}

.preserve {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 210px;
  max-width: 100%;
  height: 46px;
  margin: 15px auto 0;
  background: linear-gradient(135deg, #5db85d, #4cae4c);
  box-shadow: 0 6px 16px rgba(93, 184, 93, 0.35);
  border-radius: 999px;
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  font-size: 1.1rem;
  transition: all .3s ease;
  box-sizing: border-box;
}

.preserve:hover {
  transform: translateY(-2px);
  background: linear-gradient(135deg, #67c267, #5db85d);
  box-shadow: 0 8px 22px rgba(93, 184, 93, 0.45);
}

.save {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 280px;
  height: 46px;
  margin: 0 auto;
  padding: 0;
  background: #f5f5f5;
  color: #666;
  border: 1px solid #e0e0e0;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 600;
  font-size: 1.1rem;
  line-height: 1;
  box-sizing: border-box;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
  transition: all .3s ease;
  font-family: -apple-system, sans-serif;
}

.save:hover {
  background: #eeeeee;
  color: #333;
  transform: translateY(-2px); 
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.1);
}

.fixed-button {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%) scale(1);
  width: calc(100% - 80px);
  max-width: 500px;
  z-index: 1000;
  will-change: transform, opacity; 
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  pointer-events: none;
}

.fixed-button.hidden {
  transform: translateX(-50%) translateY(20px) scale(0.85);
  opacity: 0;
}

.fixed-button a {
  display: block;
  text-align: center;
  background: rgba(255, 255, 255, 0.8) !important;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  transform: translateZ(0);
  -webkit-transform: translateZ(0);
  color: #000 !important;
  padding: 10px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 600;
  box-shadow: 0 8px 32px rgba(0,0,0,0.12);
  border: 1px solid rgba(255,255,255,0.6);
  pointer-events: auto;
  transition: .3s;
}

.fixed-button a:hover {
  background: rgba(255, 255, 255, 0.95) !important;
  transform: translateY(-2px);
}

.prev-next-link {
  display: block;
  margin: 15px 0 40px;
  text-decoration: none;
  -webkit-tap-highlight-color: transparent;
}

.prev-next-card {
  position: relative;
  width: 100%;
  aspect-ratio: 2 / 1;
  background: #000000;
  border-radius: 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.next-text {
  color: #ffffff;
  font-family: "PingFang SC", -apple-system, sans-serif;
  font-weight: 800;
  font-size: 1.8rem;
  letter-spacing: 2px;
  z-index: 2;
}

.next-sub {
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.75rem;
  letter-spacing: 4px;
  margin-top: 8px;
  z-index: 2;
  text-transform: uppercase;
}

.responsive-video {
  width: 100%;
  height: auto;
  border-radius: 8px;
  object-fit: contain;
}