/* Header design copied from index.html */
:root {
  --color-primary: #2563eb; /* kräftiges Blau analog zum IMHIS‑CI */
  --color-secondary: #0e1e40; /* dunkles Blau für Kontrast */
  --color-accent: #38bdf8; /* helles Blau für Highlights */
  --color-accent-dark: #1e40af; /* dunklere Akzentfarbe für Hover-Zustände */
  --color-accent-light: #e2e8f0; /* helle Variante für Hover-Effekte */
  --color-border: #e2e8f0; /* dezente Rahmenfarbe wie im Profil-Header */
  --gradient-start: #2563eb; /* Gradient-Startwert wie bei Florian Eisold */
  --gradient-end: #1e40af; /* Gradient-Endwert wie bei Florian Eisold */
  --color-bg: #f9fafb; /* sehr helles Grau als Hintergrund */
  --color-section: #ffffff; /* Karten- und Header-Hintergrund */
  --color-text: #1e293b; /* dunkler Grauton für Lesetext */
  --color-text-light: #475569;
  --radius-large: 1.5rem;
  --nav-height-min: 56px;
  --nav-height-max: 96px;
  --nav-height: clamp(
    var(--nav-height-min),
    calc(6vw + 16px),
    var(--nav-height-max)
  );
  --header-padding: clamp(1rem, 4vw, 20px);
}

body {
  margin: 0;
  font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  padding: 0;
  border-top: none;
  overflow-x: hidden;
}

html {
  scroll-padding-top: var(--nav-height);
  scroll-padding-top: calc(var(--nav-height) + env(safe-area-inset-top));
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

/* Defer rendering of offscreen sections to speed up initial paint */
.section {
  content-visibility: auto;
  contain-intrinsic-size: auto 1000px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  width: 100%;
  z-index: 1000;
  background: var(--color-section);
  border-bottom: 1px solid var(--color-border);
  box-shadow: none;
  height: var(--nav-height);
  min-height: var(--nav-height);
  display: flex;
  align-items: center;
}

.site-header .header-inner {
  width: min(100%, 1200px);
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--header-padding);
  height: var(--nav-height);
  min-height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.25rem;
  flex-wrap: wrap;
  box-sizing: border-box;
}

.site-header .logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.site-header .logo img {
  display: block;
  height: 36px;
  width: auto;
}

.site-header .nav {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  flex: 1 1 auto;
  justify-content: center;
  position: relative;
}

.site-header .nav-links {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-header .nav-links a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--color-text);
  font-weight: 500;
  font-size: 1.1rem;
  text-decoration: none;
  padding: 0.3rem 0.6rem;
  border-radius: 0.5rem;
  transition: background 0.2s ease, color 0.2s ease;
}
.site-header .nav-links a::after {
  display: none;
}

.site-header .nav-links a:hover,
.site-header .nav-links a:focus-visible {
  background: var(--color-accent-light);
  color: var(--color-secondary);
  outline: none;
}

.site-header .actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
  justify-content: flex-end;
  flex-direction: row;
}

.site-header .actions .lang-switcher {
  order: 0;
  padding: 0.2rem;
}

.site-header .actions .btn {
  order: 1;
}

.site-header .actions .btn {
  border-radius: 999px !important;
  padding: 0.5rem 1.25rem;
  font-size: 0.95rem;
  line-height: 1.1;
}
.site-header .actions .btn svg {
  width: 18px;
  height: 18px;
}

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 999px;
  border: 1px solid var(--color-accent-light);
  background: rgba(255, 255, 255, 0.88);
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.nav-toggle .hamburger {
  position: relative;
  width: 20px;
  height: 2px;
  background: var(--color-text);
  border-radius: 999px;
  transition: background 0.2s ease;
}

.nav-toggle .hamburger::before,
.nav-toggle .hamburger::after {
  content: "";
  position: absolute;
  left: 0;
  width: 20px;
  height: 2px;
  background: var(--color-text);
  border-radius: 999px;
  transition: transform 0.2s ease, background 0.2s ease, opacity 0.2s ease;
}

.nav-toggle .hamburger::before {
  transform: translateY(-6px);
}

.nav-toggle .hamburger::after {
  transform: translateY(6px);
}

.nav-toggle.open {
  background: linear-gradient(135deg, var(--color-primary), #1e40af);
  border-color: transparent;
  box-shadow: 0 12px 28px rgba(37, 99, 235, 0.35);
}

.nav-toggle:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.nav-toggle.open .hamburger {
  background: transparent;
}

.nav-toggle.open .hamburger::before {
  transform: translateY(0) rotate(45deg);
  background: #ffffff;
}

.nav-toggle.open .hamburger::after {
  transform: translateY(0) rotate(-45deg);
  background: #ffffff;
}

.nav-toggle.open .hamburger::before,
.nav-toggle.open .hamburger::after {
  opacity: 1;
}

@media (hover: hover) and (pointer: fine) {
  .nav-toggle:hover,
  .nav-toggle:focus-visible {
    background: linear-gradient(135deg, var(--color-primary), #1e40af);
    border-color: transparent;
    box-shadow: 0 12px 28px rgba(37, 99, 235, 0.35);
  }

  .nav-toggle:hover .hamburger,
  .nav-toggle:focus-visible .hamburger {
    background: transparent;
  }

  .nav-toggle:hover .hamburger::before,
  .nav-toggle:focus-visible .hamburger::before {
    transform: translateY(0) rotate(45deg);
    background: #ffffff;
  }

  .nav-toggle:hover .hamburger::after,
  .nav-toggle:focus-visible .hamburger::after {
    transform: translateY(0) rotate(-45deg);
    background: #ffffff;
  }
}

@media (max-width: 767px) {
  .site-header .header-inner {
    width: 100%;
    padding: 0 var(--header-padding);
    height: var(--nav-height);
    min-height: var(--nav-height);
    gap: 0.75rem;
    flex-wrap: nowrap;
    justify-content: flex-start;
  }

  .site-header .logo {
    flex: 0 0 auto;
  }

  .site-header .actions {
    order: 2;
    flex: 0 0 auto;
    width: auto;
    gap: 0.5rem;
    align-items: center;
    margin-left: auto;
    display: inline-flex;
    justify-content: flex-end;
  }

  .site-header .actions .lang-switcher {
    flex: 0 0 auto;
    justify-content: center;
  }

  .site-header .actions .btn {
    display: none;
  }

  .site-header .nav {
    order: 3;
    flex: 0 0 auto;
    justify-content: flex-end;
    width: auto;
    margin-left: 0;
    min-width: 44px;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .site-header .nav-links {
    position: absolute;
    top: calc(100% + 0.75rem);
    left: auto;
    right: calc(-1 * var(--header-padding));
    width: min(20rem, calc(100vw - var(--header-padding)));
    flex-direction: column;
    align-items: stretch;
    gap: 1rem;
    padding: 1.25rem;
    background: var(--color-section);
    border: 1px solid var(--color-accent-light);
    border-radius: var(--radius-large);
    box-shadow: 0 18px 40px rgba(15, 23, 42, 0.18);
    transform: translateY(-12px);
    transform-origin: top right;
    opacity: 0;
    pointer-events: none;
    transition: transform 0.3s ease, opacity 0.3s ease;
    z-index: 1100;
  }

  .site-header .nav-links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }

  .site-header .nav-links li {
    width: 100%;
    text-align: center;
  }

  .site-header .nav-links a {
    width: 100%;
    justify-content: center;
    font-size: 1.05rem;
    text-align: center;
  }

}

@media (min-width: 768px) {
  .site-header .header-inner {
    flex-wrap: nowrap;
  }

  .site-header .nav {
    justify-content: center;
  }

  .site-header .actions {
    flex-wrap: nowrap;
  }
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  border: none;
  cursor: pointer;
  transition: background 0.3s ease, color 0.3s ease, box-shadow 0.3s ease, transform 0.18s ease;
  gap: 0.5rem;
}

.btn.primary {
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  color: #fff;
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.35);
}

.btn.primary:hover {
  background: linear-gradient(135deg, #1e4fd1, var(--color-accent-dark));
  transform: translateY(-1px);
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.4);
}

.btn.secondary {
  background: var(--color-accent-light);
  color: var(--color-accent-dark);
  border: 1px solid var(--color-accent-dark);
  box-shadow: 0 6px 16px rgba(37, 99, 235, 0.15);
}

.btn.secondary:hover {
  background: #d5e5fb;
}

/* Prevent line breaks in header CTA buttons */
.nav-actions .btn {
  white-space: nowrap;
}

.btn svg {
  width: 20px;
  height: 20px;
}

/* Ensure CTA buttons in the book section share equal height */
.book-section .order-buttons {
  align-items: stretch;
}


.about-cta,
.about-content .about-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  margin: 1.2rem auto 0;
  width: fit-content;
  white-space: nowrap;
}

.about-cta svg {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  display: inline-block;
}

  .about-cta span {
    line-height: 1;
  }

  .about-cta-group {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin-top: 1.2rem;
  }

  .about-cta-group .about-cta {
    margin: 0;
  }

  /* Benefit section: align intro centrally, keep cards centred */
  .section-benefit > h2 {
    text-align: left;
    margin-left: 0;
  }

  .section-benefit > p.lead {
    text-align: left;
    max-width: 46rem;
  }

  .section-benefit .eyebrow {
    display: inline-flex;
    align-items: center;
    padding: 0.4rem 1rem;
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--color-primary);
    background: rgba(37, 99, 235, 0.08);
    border: 1px solid rgba(37, 99, 235, 0.15);
    margin: 0 0 1.4rem;
  }

  .section-benefit .toggle-container {
    margin: 0 0 2rem;
  }

  .section-benefit .benefit-cards {
    justify-items: stretch;
  }

  .section-benefit .card {
    align-items: flex-start;
    text-align: left;
  }

  .section-benefit .card-desc {
    text-align: left;
  }

  .section-benefit .cta-row {
    justify-content: flex-start;
  }

  @media (max-width: 720px) {
    .section-benefit > h2,
    .section-benefit > p.lead {
      text-align: left;
      margin-left: 0;
      margin-right: 0;
    }

    .section-benefit .eyebrow {
      justify-content: flex-start;
      margin: 0 0 1.4rem;
    }

    .section-benefit .toggle-container {
      margin: 0 auto 2rem;
    }

    .section-benefit .benefit-cards {
      justify-items: center;
    }

    .section-benefit .card {
      align-items: center;
      text-align: center;
    }

    .section-benefit .card-desc {
      text-align: center;
    }

    .section-benefit .cta-row {
      justify-content: center;
    }
  }

  .cta-icon {
    font-size: 1.1rem;
    line-height: 1;
    display: inline-flex;
    align-items: center;
  }
  .cta-icon svg {
    width: 20px;
    height: 20px;
  }

  .footer-cta {
    gap: 0.6rem;
  }

  .contact-footer {
    text-align: center;
    padding: 3rem 1rem;
  }

  .contact-footer .footer-cta {
    margin: 0 auto;
  }

  /* Custom styles for navigation and language toggle */
  .nav-toggle {
    border: 2px solid var(--link);
    border-radius: 999px;
    background: transparent;
    transition: background 0.2s ease;
  }

  .nav-toggle .hamburger,
  .nav-toggle .hamburger::before,
  .nav-toggle .hamburger::after {
    background: var(--link);
  }

  .nav-toggle.open {
    background: var(--link);
  }

  .nav-toggle.open .hamburger,
  .nav-toggle.open .hamburger::before,
  .nav-toggle.open .hamburger::after {
    background: #fff;
  }

  @media (hover: hover) and (pointer: fine) {
    .nav-toggle:hover,
    .nav-toggle:focus-visible {
      background: var(--link);
    }

    .nav-toggle:hover .hamburger,
    .nav-toggle:focus-visible .hamburger,
    .nav-toggle:hover .hamburger::before,
    .nav-toggle:focus-visible .hamburger::before,
    .nav-toggle:hover .hamburger::after,
    .nav-toggle:focus-visible .hamburger::after {
      background: #fff;
    }
  }

.lang-switcher {
  display: inline-flex;
  align-items: center;
  gap: 0.2rem;
  padding: 0.2rem;
  background: var(--color-section);
  border: 1px solid var(--color-border);
  border-radius: 999px;
}

.lang-btn {
  padding: 0.3rem 0.8rem;
  background: transparent;
  border: none;
  border-radius: 999px;
  color: var(--color-text);
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
}

.lang-btn[aria-pressed="true"] {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.25);
}

.lang-btn:not([aria-pressed="true"]):hover {
  background: var(--color-accent-light);
  color: var(--color-secondary);
}

/* Style quote lines in About section */
.about-quote {
  font-weight: 400;
}

.about-quote .quote-emphasis {
  font-size: clamp(1.3rem, 3vw, 1.6rem);
  font-weight: 600;
}


/* Badge indicating free university e-book access */
.trust-badge.free-access {
  background: var(--accent-light);
  color: var(--link);
}

.trust-badge.free-access .dot {
  background: var(--link);
}

#publications .section-frame p {
  margin-bottom: 1.5rem;
}