Here is your updated CSS with the “About Aristo-Tec” <h2> centered properly.

Since your About section uses:

<section id="about" class="about-section">


I added a specific rule for .about-section h2 so it centers that heading without affecting others.

I also quietly fixed one small issue: opacity: 50; was invalid (opacity must be between 0–1), so I corrected it to 0.

✅ Updated CSS (Ready to Replace Yours)
/* Reset & base */
* { 
  margin: 0; 
  padding: 0; 
  box-sizing: border-box; 
}

body { 
  font-family: Arial, sans-serif; 
  line-height: 1.6; 
}

/* Container */
.container { 
  max-width: 1100px; 
  margin: auto; 
  padding: 20px; 
}

/* Headers & Nav */
.site-header {
  background: #111;
  text-align: center;
}

.header-image {
  width: 100%;
  max-width: 1200px;
  height: auto;
  display: block;
  margin: 0 auto;
}

.main-nav {
  background: #222;
  padding: 10px;
}

.main-nav a {
  color: #fff;
  margin: 0 12px;
  text-decoration: none;
  font-weight: 500;
}

.main-nav a:hover {
  text-decoration: underline;
}

.btn { 
  padding: 10px 18px; 
  border: none; 
  cursor: pointer; 
}

.btn.primary { 
  background: #0056b3; 
  color: #fff; 
  border-radius: 4px; 
}

/* Hero Section – skinnier and grey background */
.hero { 
  background: #f4f4f4;
  color: #222;
  text-align: center; 
  padding: 30px 20px;
}

.hero h2 { 
  font-size: 2rem; 
  margin-bottom: 10px; 
  color: #222;
}

.hero .btn.primary {
  background: #0056b3;
  color: #fff;
}

/* Video Section with fade effect */
.video-section {
  display: flex;
  justify-content: center;
  padding: 30px 0;
  background: #111;
}

.video-fade-wrapper {
  position: relative;
  width: 90%;
  max-width: 1000px;
  overflow: hidden;
  border-radius: 20px;

  /* Fade-in animation */
  opacity: 0;
  animation: fadeIn 1.2s ease-in-out forwards;
}

.video-fade-wrapper::after {
  content: "";
  position: absolute;
  top: 0; 
  left: 0;
  width: 100%; 
  height: 100%;
  pointer-events: none;
  z-index: 2;
  background: radial-gradient(circle, rgba(0,0,0,0) 85%, rgba(0,0,0,0.7) 100%);
  border-radius: 20px;
}

.video-fade-wrapper video {
  width: 100%;
  height: auto;
  display: block;
  position: relative;
  z-index: 1;
  border-radius: 20px;
  object-fit: cover;
}

/* Fade-in keyframes */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Sections */
.section { 
  padding: 40px 0; 
}

/* Center About Section H2 */
.about-section h2 {
  text-align: center;
  margin-bottom: 30px;
}

.section h2 {
  text-align: center;
  margin-bottom: 30px;
}

.grid { 
  display: flex; 
  gap: 20px; 
  flex-wrap: wrap; 
}

.card { 
  flex: 1; 
  min-width: 250px; 
  padding: 20px; 
  border: 1px solid #ddd; 
  border-radius: 6px; 
}

.card h2,
.card h3 {
  text-align: center;
  margin-bottom: 15px;
}

/* Footer */
.footer { 
  background: #333; 
  color: #fff; 
  text-align: center; 
  padding: 20px; 
}

/* Modal */
.modal { 
  display: none; 
  position: fixed; 
  left: 0; 
  top: 0; 
  width: 100%; 
  height: 100%; 
  background: rgba(0,0,0,0.6); 
}

.modal-content { 
  background: #fff; 
  padding: 30px; 
  margin: 80px auto; 
  width: 90%; 
  max-width: 500px; 
  border-radius: 8px; 
}

.close { 
  float: right; 
  font-size: 1.4rem; 
  cursor: pointer; 
}

input, 
textarea { 
  width: 100%; 
  margin: 8px 0; 
  padding: 10px; 
  border: 1px solid #ccc; 
  border-radius: 4px; 
}