/* Reset + Base */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  font-family: "Segoe UI", Roboto, Arial, sans-serif;
  background-color: #f4f6f8;
  color: #333;
  line-height: 1.6;
}

/* Header */
header {
  position: relative;
  overflow: hidden;
  text-align: center;
  padding: 2rem 1rem;
  background: linear-gradient(to right, #004d40, #00796b);
  color: white;
}
.logo {
  max-width: 180px;
  margin-bottom: 1rem;
}
header h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}
header p {
  font-size: 1.1rem;
}

/* Background video */
.bg-video {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: -1;
  opacity: 0.2;
}

/* Grid for system cards */
main {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 2rem 1rem;
}
.button-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1.5rem;
}
.card {
  flex: 1 1 260px;
  text-decoration: none;
  color: white;
  font-weight: bold;
  text-align: center;
  padding: 2rem;
  border-radius: 16px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  font-size: 1.2rem;
}
.card:hover, .card:focus {
  transform: translateY(-6px);
  box-shadow: 0 8px 16px rgba(0,0,0,0.15);
  outline: none;
}

/* EMUEA colors */
.green {
  background-color: #2e7d32;
}
.blue {
  background-color: #0288d1;
}
.orange {
  background-color: #ef6c00;
}
.red {
  background-color: #d32f2f;
}

/* Footer */
footer {
  text-align: center;
  background-color: #e0e0e0;
  padding: 1rem;
  font-size: 1rem;
  color: #333;
  font-weight: 600;
}

/* Responsive tweaks */
@media (max-width: 768px) {
  header h1 {
    font-size: 1.6rem;
  }
  .card {
    flex: 1 1 100%;
  }
}