:root {
  --primary: #3498db;
  --secondary: #2980b9;
  --accent: #e74c3c;
  --teal: #0e83b5;
  --white: #ffffff;
  --light-bg: #ecf0f1;
  --text-dark: #2c3e50;
  --text-light: #7f8c8d;
  --border-color: #bdc3c7;
  --radius: 8px;
  --shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.15);
}

html {
  font-size: 62.5%;
}

body {
  display: grid;
  grid-template-columns: 1fr 2fr 1fr;
  grid-template-rows: auto auto auto;
  grid-template-areas:
    "header empty nav"
    "main main main"
    "footer footer footer";
  gap: 10px;
}

header {
  display: flex;
  align-items: center;
  padding: 2rem;
  background-color: var(--primary);
  box-shadow: var(--shadow);
  grid-area: header;

  & #link-img {
    display: flex;
    align-items: center;

    & a {
      display: inline-block;
      transition:
        transform 0.3s ease,
        opacity 0.3s ease;

      &:hover {
        transform: scale(1.05);
        opacity: 0.85;
      }
    }
  }

  & #php-img {
    height: 15rem;
    width: auto;
    object-fit: contain;
  }
}

.empty {
  grid-area: empty;
  background-color: var(--primary);
}

nav {
  grid-area: nav;
  background-color: var(--primary);
  padding: 0;

  display: flex;
  justify-content: center;
}

nav ul {
  display: flex;
  list-style: none;
  gap: 0;
  padding: 0;
  margin: 0;
  width: 100%;
}

nav li {
  flex: 1;
}

nav a {
  display: block;
  padding: 1.5rem 2rem;
  text-decoration: none;
  color: white;
  font-weight: 600;
  font-size: 2.2rem;
  text-align: center;

  transition:
    background-color 0.2s,
    color 0.2s;

  border-bottom: 3px solid transparent;
}

nav a:hover {
  background-color: var(--secondary);
  border-bottom-color: var(--accent);
}

main {
  grid-area: main;
  display: flex;
  margin: 0 auto;
  max-width: 100%;
  align-content: center;
  justify-content: center;

  /* main is am asrsch, display flex zu block und trotzdem EInleitung zentrieren */
}

#Einleitung {
  width: 50%;
}

article,
section {
  background-color: var(--white);
  padding: 2rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

article h1,
section h2 {
  color: var(--primary);
  margin-bottom: 1.5rem;
  font-size: 2.8rem;
}

article h1 {
  font-size: 3.2rem;
}

article p,
section p {
  color: var(--text-light);
  margin-bottom: 1rem;
  font-size: 1.8rem;
}

img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  display: block;
}

audio,
video {
  width: 100%;
  max-width: 100%;
  margin: 1rem 0;
  border-radius: var(--radius);
}

iframe {
  border-radius: var(--radius);
  margin: 1rem 0;
}

form {
}

footer {
  grid-area: footer;
  background-color: var(--primary);
  color: var(--white);
  text-align: center;
  padding: 2rem;
  margin-top: auto;
  font-size: 1.4rem;
  box-shadow: 0 -2px 8px rgba(0, 0, 0, 0.1);
}

footer p {
  margin: 0;
}

@media (max-width: 768px) {
  body {
    grid-template-columns: 1fr;
  }

  header {
    padding: 1.5rem;
  }

  nav ul {
    flex-direction: column;
  }

  nav a {
    padding: 1rem 1.5rem;
    font-size: 1.6rem;
  }

  main {
    padding: 1.5rem 1rem;
  }

  article,
  section {
    padding: 1.5rem;
    margin-bottom: 1.5rem;
  }

  article h1,
  section h2 {
    font-size: 2.2rem;
  }

  #php-img {
    height: 4rem;
  }
}