:root {
  /* Farben */
  --primary-color: #0066cc;
  --secondary-color: #00a86b;
  --text-color: #333333;
  --background-color: #ffffff;
  --accent-color: #ff6b6b;

  /* Schriftarten */
  --font-primary: 'Roboto', sans-serif;
  --font-secondary: 'Open Sans', sans-serif;

  /* Abstände und Größen */
  --spacing-small: 0.5rem;
  --spacing-medium: 1rem;
  --spacing-large: 2rem;

  /* Schatten und Übergänge */
  --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --transition: all 0.3s ease;
}

/* Globale Stile */
body {
  font-family: var(--font-primary);
  color: var(--text-color);
  line-height: 1.6;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-medium);
}

h1, h2, h3 {
  font-family: var(--font-secondary);
}

h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
}

h2 {
  font-size: clamp(1.5rem, 4vw, 2.5rem);
}

h3 {
  font-size: clamp(1.2rem, 3vw, 1.8rem);
}

/* Header und Navigation */
header {
  background-color: var(--background-color);
  box-shadow: var(--box-shadow);
  position: fixed;
  width: 100%;
  z-index: 1000;
}

nav ul {
  display: flex;
  justify-content: space-around;
  list-style-type: none;
  padding: 0;
}

nav a {
  color: var(--text-color);
  text-decoration: none;
  padding: var(--spacing-small) var(--spacing-medium);
  transition: var(--transition);
}

nav a:hover {
  color: var(--primary-color);
}

/* Hero Section */
.hero {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: var(--background-color);
  text-align: center;
  padding: calc(var(--spacing-large) * 3) var(--spacing-medium);
}

.cta-button {
  display: inline-block;
  background-color: var(--accent-color);
  color: var(--background-color);
  padding: var(--spacing-medium) var(--spacing-large);
  border-radius: 30px;
  text-decoration: none;
  transition: var(--transition);
}

.cta-button:hover {
  background-color: darken(var(--accent-color), 10%);
  transform: translateY(-2px);
}

/* Services Section */
.service-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-large);
}

.service-card {
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(10px);
  border-radius: 10px;
  padding: var(--spacing-large);
  box-shadow: var(--box-shadow);
  transition: var(--transition);
}

.service-card:hover {
  transform: translateY(-5px);
}

.service-card img {
  max-width: 60px;
  margin-bottom: var(--spacing-medium);
}

/* About Section */
.about {
  background-color: #f8f8f8;
  padding: var(--spacing-large) 0;
}

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

.usp-list li::before {
  content: "✓";
  color: var(--secondary-color);
  margin-right: var(--spacing-small);
}

/* Case Studies Section */
.case-study-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-large);
}

.case-study-card {
  background-color: var(--background-color);
  border-radius: 10px;
  padding: var(--spacing-large);
  box-shadow: var(--box-shadow);
}

/* Contact Form */
.contact form {
  display: grid;
  gap: var(--spacing-medium);
}

.contact input,
.contact textarea {
  width: 100%;
  padding: var(--spacing-small);
  border: 1px solid #ddd;
  border-radius: 5px;
}

.contact button {
  background-color: var(--primary-color);
  color: var(--background-color);
  border: none;
  padding: var(--spacing-medium);
  border-radius: 5px;
  cursor: pointer;
  transition: var(--transition);
}

.contact button:hover {
  background-color: darken(var(--primary-color), 10%);
}

/* Footer */
footer {
  background-color: var(--text-color);
  color: var(--background-color);
  text-align: center;
  padding: var(--spacing-medium);
}

/* Responsive Design */
@media (max-width: 768px) {
  nav ul {
    flex-direction: column;
    align-items: center;
  }

  nav li {
    margin-bottom: var(--spacing-small);
  }
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
  :root {
    --text-color: #ffffff;
    --background-color: #1a1a1a;
  }

  .service-card,
  .case-study-card {
    background-color: rgba(255, 255, 255, 0.1);
  }
}

/* Accessibility */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.fade-in {
  animation: fadeIn 1s ease-out;
}

/* Lazy Loading */
img.lazy {
  opacity: 0;
  transition: opacity 0.3s;
}

img.lazy.loaded {
  opacity: 1;
}