body {
  font-family: sans-serif;
  margin: 0;
  background: url('background.png') no-repeat center center fixed;
  background-size: cover;
  color: white;
}

nav {
  background-color: rgba(0, 0, 0, 0.8);
  padding: 1em;
  margin-bottom: 2em;
}

.tabs {
  display: flex;
  list-style: none;
  justify-content: center;
  gap: 2em;
  margin: 0;
  padding: 0;
}

.tabs li {
  color: white;
  cursor: pointer;
  padding: 0.5em 1em;
  border-radius: 5px;
  transition: background-color 0.3s ease, transform 0.2s ease;
}

.tabs li:hover {
  background-color: #555;
  transform: scale(1.05);
}

.tabs li.active {
  background-color: #888;
}

main {
  padding: 2em;
  max-width: 800px;
  margin: 4em auto;
  border-radius: 12px;
  background: linear-gradient(to bottom, #171723, #262333); /* dark blue-gray to slightly brighter */
  box-shadow: 0 0 20px rgba(0,0,0,0.4);
  transition: opacity 0.5s ease;
}

.content-section {
  display: none;
  opacity: 0;
  transition: opacity 0.5s ease;
}

.content-section:not(.hidden) {
  display: block;
  opacity: 1;
}

.hidden {
  display: none !important;
}

.timeline {
  list-style: none;
  padding-left: 0;
}

.timeline li {
  margin-bottom: 0.75em;
}

a {
  color: #8cf;
}

a:hover {
  text-decoration: underline;
}

.video-container {
  position: relative;
  width: 50%;           /* Half the width of its container */
  padding-bottom: 28.125%; /* 50% of 56.25% for 16:9 ratio */
  padding-top: 25px;
  height: 0;
  overflow: hidden;
  border-radius: 12px;
  margin-top: 1em;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

.video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}