* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Andada Pro', Georgia, serif;
  line-height: 1.6;
  background-color: #fdfdfd;
  color: #333;
}

h1 {
  font-family: 'Habibi', serif;
}

nav {
  display: flex;
  justify-content: center;
  padding: 20px;
  background: #ffffffcc;
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 100;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 50px;
  flex-wrap: wrap;
}

nav a {
  text-decoration: none;
  color: #007acc;
  font-weight: bold;
  position: relative;
  padding: 20px;
}

nav a::after {
  content: '';
  position: absolute;
  width: 0%;
  height: 2px;
  left: 0;
  bottom: 0;
  background: #007acc;
  transition: width 0.3s;
}

nav a:hover::after {
  width: 100%;
}

/* Hero Section */
.startpage {
  position: relative;
  background: url('pictures/frontpage.png') center/cover no-repeat;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: white;
  overflow: hidden;
}

.overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.4);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.start-text h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  margin-bottom: 0.5em;
  text-shadow: 1px 1px 4px #000;
}

.start-text p {
  font-size: clamp(1rem, 2vw, 1.5rem);
  text-shadow: 1px 1px 3px #000;
}

/* Section Container */
section {
  padding: 80px 0;
}

.section-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 80px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 40px;
}

section:nth-of-type(odd) {
  background-color: #ffffff;
}

section:nth-of-type(even) {
  background-color: #f0f4f8;
}

h2 {
  font-size: 2.5rem;
  margin-bottom: 20px;
  color: #007acc;
}

.split.reverse {
  flex-direction: row-reverse;
}

.section-container .text {
  flex: 1 1 50%;
}

.section-container .image {
  flex: 1 1 30%;
  text-align: center;
}

.section-container .image img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
}

.quiz-btn {
  margin-top: 1rem;
  padding: 0.75rem 1.5rem;
  border-radius: 12px;
  font-weight: bold;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  display: inline-block;
}


.quiz-btn:hover {
  opacity: 0.9;
}

.quiz-btn.selected {
  border: 3px solid #fff;
  box-shadow: 0 0 8px rgba(0,0,0,0.2);
}

.quiz-btn.selected {
  background-color: #007acc;
  color: white;
  border: 2px solid #005f99;
}

/* Footer */
footer {
  text-align: center;
  padding: 30px;
  background-color: #eee;
  font-size: 0.9rem;
}

/* Fade-in Animation */
.fade-in-element {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-element.visible {
  opacity: 1;
  transform: translateY(0);
}

.timeline {
  position: relative;
  padding-left: 30px;
  border-left: 4px solid #007acc;
  margin-top: 30px;
}

.timeline-item {
  position: relative;
  margin-bottom: 30px;
  padding-left: 20px;
  animation: slideIn 0.6s ease forwards;
  opacity: 0;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -10px;
  top: 0;
  width: 16px;
  height: 16px;
  background-color: #007acc;
  border-radius: 50%;
  border: 3px solid white;
}

.timeline-date {
  font-weight: bold;
  margin-bottom: 5px;
}

.timeline-content {
  background: #f0f4f8;
  padding: 12px 18px;
  border-radius: 6px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

@keyframes slideIn {
  0% { opacity: 0; transform: translateY(20px); }
  100% { opacity: 1; transform: translateY(0); }
}


.quiz-box {
  background: #ffffff;
  border: 2px solid #007acc;
  padding: 20px;
  border-radius: 10px;
  margin-top: 20px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.quiz-question {
  font-weight: bold;
  margin-bottom: 16px;
}

.quiz-options {
  display: flex;
  gap: 15px;
  flex-wrap: wrap;
}

.quiz-btn {
  padding: 10px 20px;
  border: 2px solid #007acc;
  background: white;
  border-radius: 5px;
  cursor: pointer;
  transition: all 0.3s;
}

.quiz-btn:hover {
  background: #007acc;
  color: white;
}

.quiz-feedback {
  margin-top: 16px;
  font-weight: bold;
}


/* Smaller images for concept and technology sections */
.small-image  {
  max-width: 30%;
  margin: 0 auto;
}

/* Button on start overlay */
.start-button {
  margin-top: 60px;
  padding: 14px 24px;
  background-color: #007acc;
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  text-decoration: none;
  transition: background-color 0.3s;
}

.start-button:hover {
  background-color: #005f99;
}

.image img {
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.image img:hover {
  transform: scale(1.05);
  box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.scroll-down {
  font-size: 2rem;
  margin-top: 40px;
  animation: bounce 2s infinite;
  color: white;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(10px); }
}



/* Responsive Layout */
@media (max-width: 768px) {
  .section-container {
    flex-direction: column;
    padding: 0 20px;
  }

  nav ul {
    flex-direction: column;
    gap: 15px;
    align-items: center;
  }

  .start-text h1 {
    font-size: 2.5rem;
  }

  .start-text p {
    font-size: 1.2rem;
  }
}