body {
  margin: 0;
  padding: 0;
  height: 200vh; /* Just to enable scrolling */
  font-family: Arial, sans-serif;
}

/* Header Styling */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: transparent;
  transition: background 0.3s ease-in-out;
  z-index: 1000;
}

.container-fluid {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 20px;
}

/* Logo container */
.logo {
  position: relative;
  display: flex;
  align-items: center;
  height: 50px;
}

/* Default and Alternate Logos */
.logo img {
  height: 50px;
  transition: opacity 0.3s ease-in-out;
  position: absolute;
  left: 0;
  top: 0;
}

.logo .logo-scroll {
  opacity: 0;
}

/* When scrolled, swap logos */
.scrolled .logo .logo-default {
  opacity: 0;
}

.scrolled .logo .logo-scroll {
  opacity: 1;
}