/* ============================================================
   BAV Gebäudetechnik – StoryBrand OnePager
   Design System & Styles
   ============================================================ */

/* ---------- Design Tokens ---------- */
:root {
  --clr-primary: #00818a;
  --clr-primary-dark: #006670;
  --clr-primary-light: #e8f5f5;
  --clr-dark: #1a1a2e;
  --clr-text: #2d2d2d;
  --clr-gray: #6b7280;
  --clr-light: #f7f8fa;
  --clr-white: #ffffff;
  --clr-border: #e5e7eb;
  --clr-success: #10b981;

  --font-main: 'Inter', system-ui, -apple-system, sans-serif;

  --fs-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.8125rem);
  --fs-sm: clamp(0.875rem, 0.82rem + 0.27vw, 0.9375rem);
  --fs-base: clamp(1rem, 0.95rem + 0.25vw, 1.0625rem);
  --fs-lg: clamp(1.125rem, 1rem + 0.5vw, 1.25rem);
  --fs-xl: clamp(1.25rem, 1.1rem + 0.75vw, 1.5rem);
  --fs-2xl: clamp(1.5rem, 1.2rem + 1.5vw, 2rem);
  --fs-3xl: clamp(1.875rem, 1.4rem + 2.3vw, 2.75rem);
  --fs-hero: clamp(2rem, 1.2rem + 4vw, 3.5rem);

  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2.5rem;
  --space-xl: 4rem;
  --space-2xl: 6rem;
  --space-3xl: 8rem;

  --radius-sm: 8px;
  --radius: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
  --shadow-header: 0 2px 20px rgba(0, 0, 0, 0.08);

  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);

  --header-h: 80px;
  --max-w: 1200px;
}

/* ---------- Reset ---------- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-h);
}

body {
  font-family: var(--font-main);
  font-size: var(--fs-base);
  line-height: 1.7;
  color: var(--clr-text);
  background: var(--clr-white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--clr-primary);
  text-decoration: none;
  transition: color var(--transition);
}

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

ul,
ol {
  list-style: none;
}

/* ---------- Focus Styles ---------- */
:focus-visible {
  outline: 3px solid var(--clr-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* ---------- Skip Link ---------- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-sm);
  z-index: 10000;
  padding: var(--space-xs) var(--space-sm);
  background: var(--clr-primary);
  color: var(--clr-white);
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  font-weight: 600;
  transition: top var(--transition);
}

.skip-link:focus {
  top: 0;
}

/* ---------- Container ---------- */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: 0.75rem 1.75rem;
  font-family: var(--font-main);
  font-size: var(--fs-sm);
  font-weight: 600;
  border: 2px solid transparent;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  line-height: 1.4;
  background: var(--clr-primary);
  color: var(--clr-white);
}

.btn:hover,
.btn:focus-visible {
  background: var(--clr-primary-dark);
  color: var(--clr-white);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-primary {
  background: var(--clr-primary);
  color: var(--clr-white);
}

.btn-lg {
  padding: 1rem 2.5rem;
  font-size: var(--fs-lg);
}

.btn-sm {
  padding: 0.5rem 1.25rem;
  font-size: var(--fs-xs);
}

/* ============================================================
   HEADER
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-h);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: box-shadow var(--transition);
}

.site-header.scrolled {
  box-shadow: var(--shadow-header);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo-link {
  flex-shrink: 0;
}

.logo-img {
  height: 64px;
  width: auto;
}

/* Nav */
.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.nav-link {
  padding: 0.5rem 0.875rem;
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--clr-text);
  border-radius: var(--radius-full);
  transition: all var(--transition);
  position: relative;
  white-space: nowrap;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--clr-primary);
  transition: all var(--transition);
  transform: translateX(-50%);
  border-radius: 1px;
}

.nav-link:hover,
.nav-link.active {
  color: var(--clr-primary);
}

.nav-link.active::after {
  width: 60%;
}

.nav-cta {
  background: var(--clr-primary);
  color: var(--clr-white) !important;
  font-weight: 600;
  margin-left: var(--space-xs);
}

.nav-cta::after {
  display: none;
}

.nav-cta:hover {
  background: var(--clr-primary-dark);
  color: var(--clr-white) !important;
  transform: translateY(-1px);
}

/* Burger */
.burger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  z-index: 1001;
}

.burger-line {
  width: 100%;
  height: 2.5px;
  background: var(--clr-text);
  border-radius: 2px;
  transition: all var(--transition);
  transform-origin: center;
}

.burger.active .burger-line:nth-child(1) {
  transform: translateY(7.5px) rotate(45deg);
}

.burger.active .burger-line:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.burger.active .burger-line:nth-child(3) {
  transform: translateY(-7.5px) rotate(-45deg);
}

/* ============================================================
   SECTIONS – general
   ============================================================ */
.section {
  padding: var(--space-3xl) 0;
}

.section:nth-child(even) {
  background: var(--clr-light);
}

.section-title {
  font-size: var(--fs-3xl);
  font-weight: 800;
  color: var(--clr-dark);
  margin-bottom: var(--space-sm);
  text-align: center;
}

.section-intro {
  max-width: 640px;
  margin: 0 auto var(--space-xl);
  text-align: center;
  color: var(--clr-gray);
  font-size: var(--fs-lg);
  line-height: 1.7;
}

/* ============================================================
   HERO (#schmerz)
   ============================================================ */
.hero-section {
  padding-top: calc(var(--header-h) + var(--space-3xl));
  background: linear-gradient(165deg, var(--clr-white) 0%, var(--clr-primary-light) 50%, var(--clr-white) 100%);
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
  margin-bottom: var(--space-xl);
}

.hero-h1 {
  font-size: var(--fs-hero);
  font-weight: 800;
  line-height: 1.15;
  color: var(--clr-dark);
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
}

.hero-sub {
  font-size: var(--fs-xl);
  color: var(--clr-gray);
  line-height: 1.65;
  margin-bottom: var(--space-lg);
  max-width: 680px;
  margin-left: auto;
  margin-right: auto;
}

.hero-cta {
  font-size: var(--fs-lg);
  padding: 1rem 2.5rem;
}

/* Benefit Strip */
.benefit-strip {
  text-align: center;
  padding: var(--space-lg) 0;
  margin-bottom: var(--space-xl);
  border-top: 1px solid var(--clr-border);
  border-bottom: 1px solid var(--clr-border);
}

.benefit-strip-headline {
  font-size: var(--fs-2xl);
  font-weight: 700;
  color: var(--clr-primary);
  letter-spacing: -0.01em;
}

/* Problem Cards */
.problem-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.problem-card {
  background: var(--clr-white);
  padding: var(--space-lg);
  border-radius: var(--radius-lg);
  text-align: center;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  border: 1px solid var(--clr-border);
}

.problem-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.problem-icon {
  width: 56px;
  height: 56px;
  margin: 0 auto var(--space-sm);
  color: var(--clr-primary);
}

.problem-icon svg {
  width: 100%;
  height: 100%;
}

.problem-text {
  font-size: var(--fs-lg);
  font-weight: 600;
  color: var(--clr-dark);
}

/* ============================================================
   ECOSYSTEM (#oecosystem)
   ============================================================ */
.eco-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-sm);
  max-width: 820px;
  margin: 0 auto;
}

.eco-card {
  background: var(--clr-white);
  border-radius: var(--radius);
  border: 1px solid var(--clr-border);
  overflow: hidden;
  transition: box-shadow var(--transition), border-color var(--transition);
}

.eco-card:hover {
  border-color: var(--clr-primary);
}

.eco-card--zentrale {
  border-color: var(--clr-primary);
  border-width: 2px;
  background: linear-gradient(135deg, var(--clr-white) 0%, var(--clr-primary-light) 100%);
}

.eco-card-header {
  display: grid;
  grid-template-columns: 48px 1fr auto;
  grid-template-rows: auto auto;
  gap: 0 var(--space-sm);
  align-items: center;
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  background: none;
  border: none;
  cursor: pointer;
  text-align: left;
  font-family: var(--font-main);
  transition: background var(--transition);
}

.eco-card-header:hover {
  background: rgba(0, 129, 138, 0.04);
}

.eco-card-icon {
  grid-row: 1 / 3;
  width: 48px;
  height: 48px;
  color: var(--clr-primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

.eco-card-icon svg {
  width: 40px;
  height: 40px;
}

.eco-card-title {
  font-size: var(--fs-lg);
  font-weight: 700;
  color: var(--clr-dark);
  grid-column: 2;
  grid-row: 1;
  align-self: end;
}

.eco-card-subtitle {
  font-size: var(--fs-sm);
  color: var(--clr-gray);
  grid-column: 2;
  grid-row: 2;
  align-self: start;
}

.eco-card-chevron {
  grid-row: 1 / 3;
  width: 24px;
  height: 24px;
  color: var(--clr-gray);
  transition: transform var(--transition);
}

.eco-card-header[aria-expanded="true"] .eco-card-chevron {
  transform: rotate(180deg);
}

.eco-card-details {
  padding: 0 var(--space-lg) var(--space-lg);
  padding-left: calc(48px + var(--space-lg) + var(--space-sm));
  animation: slideDown 0.3s ease-out;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.eco-card-details p {
  color: var(--clr-gray);
  margin-bottom: var(--space-sm);
  line-height: 1.7;
}

.eco-benefits {
  margin-bottom: var(--space-md);
}

.eco-benefits li {
  position: relative;
  padding-left: 1.5rem;
  margin-bottom: var(--space-xs);
  font-weight: 500;
  color: var(--clr-dark);
}

.eco-benefits li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--clr-primary);
  font-weight: 700;
}

/* ============================================================
   PLAN (#plan)
   ============================================================ */
.plan-section {
  background: var(--clr-white);
}

.stepper {
  max-width: 720px;
  margin: var(--space-xl) auto 0;
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

.step {
  display: flex;
  gap: var(--space-lg);
  align-items: flex-start;
  padding: var(--space-lg);
  background: var(--clr-white);
  border-radius: var(--radius);
  border: 1px solid var(--clr-border);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}

.step:hover {
  box-shadow: var(--shadow);
  border-color: var(--clr-primary);
  transform: translateX(4px);
}

.step-number {
  flex-shrink: 0;
  width: 52px;
  height: 52px;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-primary-dark));
  color: var(--clr-white);
  font-size: var(--fs-xl);
  font-weight: 800;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.step-title {
  font-size: var(--fs-xl);
  font-weight: 700;
  color: var(--clr-dark);
  margin-bottom: var(--space-xs);
}

.step-content p {
  color: var(--clr-gray);
  line-height: 1.65;
}

.step-connector {
  width: 3px;
  height: 32px;
  background: linear-gradient(to bottom, var(--clr-primary), var(--clr-primary-light));
  margin-left: calc(var(--space-lg) + 25px);
  border-radius: 2px;
}

/* ============================================================
   PARTNER (#partner)
   ============================================================ */
.partner-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.partner-card {
  background: var(--clr-white);
  padding: var(--space-xl) var(--space-lg);
  border-radius: var(--radius-lg);
  text-align: center;
  box-shadow: var(--shadow);
  transition: all var(--transition);
  border: 1px solid var(--clr-border);
}

.partner-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--clr-primary);
}

.partner-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto var(--space-md);
  color: var(--clr-primary);
}

.partner-icon svg {
  width: 100%;
  height: 100%;
}

.partner-card h3 {
  font-size: var(--fs-xl);
  font-weight: 700;
  color: var(--clr-dark);
  margin-bottom: var(--space-sm);
}

.partner-card p {
  color: var(--clr-gray);
  line-height: 1.7;
}

/* ============================================================
   CTA (#cta)
   ============================================================ */
.cta-section {
  background: linear-gradient(165deg, var(--clr-dark) 0%, #0f2027 50%, var(--clr-dark) 100%);
  color: var(--clr-white);
}

.cta-section .section-title {
  color: var(--clr-white);
}

.cta-content {
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.result-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-xs) var(--space-md);
  margin-top: var(--space-lg);
}

.result-list li {
  position: relative;
  padding-left: 1.5rem;
  font-size: var(--fs-lg);
  color: rgba(255, 255, 255, 0.85);
}

.result-list li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--clr-primary);
  font-weight: 700;
}

.cta-form-wrapper {
  max-width: 560px;
  margin: 0 auto;
  text-align: center;
}

.cta-headline {
  font-size: var(--fs-2xl);
  font-weight: 800;
  color: var(--clr-white);
  margin-bottom: var(--space-xl);
  line-height: 1.3;
}

/* ---------- Contact Form ---------- */
.contact-form {
  text-align: left;
}

.form-group {
  margin-bottom: var(--space-md);
}

.form-group label {
  display: block;
  margin-bottom: var(--space-xs);
  font-weight: 600;
  font-size: var(--fs-sm);
  color: rgba(255, 255, 255, 0.9);
}

.optional {
  font-weight: 400;
  color: rgba(255, 255, 255, 0.5);
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.875rem 1rem;
  font-family: var(--font-main);
  font-size: var(--fs-base);
  color: var(--clr-white);
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: rgba(255, 255, 255, 0.3);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--clr-primary);
  background: rgba(255, 255, 255, 0.12);
  box-shadow: 0 0 0 3px rgba(0, 129, 138, 0.3);
}

.form-group textarea {
  resize: vertical;
  min-height: 100px;
}

.form-group--checkbox {
  display: flex;
  align-items: flex-start;
  gap: var(--space-xs);
}

.form-group--checkbox label {
  margin-bottom: 0;
  font-weight: 400;
  font-size: var(--fs-sm);
  line-height: 1.5;
  cursor: pointer;
}

.form-group--checkbox input[type="checkbox"] {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  margin-top: 2px;
  accent-color: var(--clr-primary);
  cursor: pointer;
}

.form-group--checkbox a {
  color: var(--clr-primary);
  text-decoration: underline;
}

.contact-form .btn-lg {
  width: 100%;
  margin-top: var(--space-sm);
}

/* Success State */
.form-success {
  text-align: center;
  padding: var(--space-xl);
  animation: fadeIn 0.5s ease-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.success-icon {
  width: 72px;
  height: 72px;
  margin: 0 auto var(--space-md);
  color: var(--clr-success);
}

.success-icon svg {
  width: 100%;
  height: 100%;
}

.form-success h3 {
  font-size: var(--fs-2xl);
  margin-bottom: var(--space-sm);
}

.form-success p {
  color: rgba(255, 255, 255, 0.7);
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  background: var(--clr-dark);
  color: rgba(255, 255, 255, 0.6);
  padding: var(--space-lg) 0;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.footer-copy {
  font-size: var(--fs-sm);
}

.footer-nav {
  display: flex;
  gap: var(--space-md);
}

.footer-nav a {
  font-size: var(--fs-sm);
  color: rgba(255, 255, 255, 0.6);
  transition: color var(--transition);
}

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

/* ============================================================
   SCROLL REVEAL
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease-out, transform 0.7s ease-out;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */

/* Tablet */
@media (max-width: 1024px) {
  .problem-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }

  .partner-grid {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: var(--space-xl) auto 0;
  }
}

/* Mobile */
@media (max-width: 768px) {
  :root {
    --header-h: 64px;
  }

  .burger {
    display: flex;
  }

  .main-nav {
    position: fixed;
    top: 0;
    right: 0;
    width: min(320px, 85vw);
    height: 100vh;
    height: 100dvh;
    background: var(--clr-white);
    box-shadow: -4px 0 30px rgba(0, 0, 0, 0.15);
    transform: translateX(100%);
    transition: transform var(--transition);
    z-index: 999;
    padding: calc(var(--header-h) + var(--space-md)) var(--space-lg) var(--space-lg);
    overflow-y: auto;
  }

  .main-nav.open {
    transform: translateX(0);
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-xs);
  }

  .nav-link {
    padding: 0.875rem var(--space-sm);
    font-size: var(--fs-lg);
    border-radius: var(--radius-sm);
  }

  .nav-link::after {
    display: none;
  }

  .nav-link:hover,
  .nav-link.active {
    background: var(--clr-primary-light);
  }

  .nav-cta {
    margin-left: 0;
    margin-top: var(--space-sm);
    text-align: center;
  }

  /* Mobile overlay */
  .nav-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.4);
    z-index: 998;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition);
  }

  .nav-overlay.active {
    opacity: 1;
    pointer-events: all;
  }

  .section {
    padding: var(--space-2xl) 0;
  }

  .hero-section {
    padding-top: calc(var(--header-h) + var(--space-2xl));
  }

  .problem-grid {
    grid-template-columns: 1fr;
    max-width: 100%;
  }

  .stepper {
    margin: var(--space-lg) auto 0;
  }

  .step {
    gap: var(--space-md);
    padding: var(--space-md);
  }

  .step-number {
    width: 44px;
    height: 44px;
    font-size: var(--fs-lg);
  }

  .step-connector {
    margin-left: calc(var(--space-md) + 21px);
    height: 24px;
  }

  .eco-card-header {
    padding: var(--space-sm) var(--space-md);
    grid-template-columns: 40px 1fr auto;
  }

  .eco-card-icon {
    width: 40px;
    height: 40px;
  }

  .eco-card-icon svg {
    width: 32px;
    height: 32px;
  }

  .eco-card-details {
    padding: 0 var(--space-md) var(--space-md);
    padding-left: calc(40px + var(--space-md) + var(--space-sm));
  }

  .result-list {
    flex-direction: column;
    align-items: center;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}