body {
    margin: 0;
    font-family: 'Segoe UI', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 20px;
}

.glass-container {
    width: 90%;
    max-width: 1000px;
}

/* หัวใจหลัก: คลาสกระจก */
.glass-card {
  width: 240px;
  height: 360px;
  background: rgba(255, 255, 255, 0.13);
  backdrop-filter: blur(5px);
  -webkit-backdrop-filter: blur(5px);
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.3);
  box-shadow: 
    0 8px 32px rgba(0, 0, 0, 0.1),
    inset 0 1px 0 rgba(255, 255, 255, 0.5),
    inset 0 -1px 0 rgba(255, 255, 255, 0.1),
    inset 0 0 4px 2px rgba(255, 255, 255, 0.2);
  position: relative;
  overflow: hidden;
}

.glass-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.8),
    transparent
  );
}

.glass-card::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 1px;
  height: 100%;
  background: linear-gradient(
    180deg,
    rgba(255, 255, 255, 0.8),
    transparent,
    rgba(255, 255, 255, 0.3)
  );
}