:root {
  --c-primary: #6366f1;
  --c-primary-light: #818cf8;
  --c-primary-dark: #4f46e5;
  --c-primary-bg: #eef2ff;
  --c-success: #10b981;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-card: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.04);
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: #fff;
  color: var(--gray-800);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* === Topbar === */
.landing-topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  height: 64px;
  background: rgba(255,255,255,0.9);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--gray-200);
}

.landing-topbar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--gray-900);
  font-weight: 700;
  font-size: 18px;
}

.landing-topbar-brand svg { flex-shrink: 0; }

.landing-topbar-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.landing-topbar-nav {
  display: flex;
  align-items: center;
  gap: 8px;
}

.landing-topbar-nav a {
  color: var(--gray-500);
  font-size: 13px;
  font-weight: 500;
  text-decoration: none;
  padding: 6px 14px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.landing-topbar-nav a:hover {
  color: var(--gray-900);
  border-color: var(--gray-200);
  background: var(--gray-50);
}

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  text-decoration: none;
  border: none;
  transition: all 0.15s ease;
}

.btn-primary {
  background: var(--c-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--c-primary-dark); }

.btn-outline {
  background: transparent;
  color: var(--gray-700);
  border: 1px solid var(--gray-300);
}
.btn-outline:hover {
  background: var(--gray-50);
  border-color: var(--gray-400);
}

.btn-lg {
  padding: 14px 28px;
  font-size: 16px;
  border-radius: var(--radius-lg);
}

.btn-ghost {
  background: transparent;
  color: var(--gray-600);
  padding: 8px 16px;
}
.btn-ghost:hover { color: var(--c-primary); background: var(--gray-50); }

/* === Container === */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 32px;
}

/* === Hero === */
.hero {
  padding: 100px 0 80px;
  text-align: center;
  background: linear-gradient(180deg, #fff 0%, var(--gray-50) 100%);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 20px;
  background: var(--c-primary-bg);
  color: var(--c-primary);
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 24px;
}

.hero h1 {
  font-size: 56px;
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 20px;
  color: var(--gray-900);
  letter-spacing: -1px;
}

.hero h1 span { color: var(--c-primary); }

.hero p {
  font-size: 18px;
  color: var(--gray-500);
  max-width: 600px;
  margin: 0 auto 36px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 48px;
  margin-top: 64px;
}

.hero-stat { text-align: center; }

.hero-stat-value {
  font-size: 32px;
  font-weight: 700;
  color: var(--gray-900);
}

.hero-stat-label {
  font-size: 14px;
  color: var(--gray-500);
  margin-top: 4px;
}

/* === Sections === */
.section {
  padding: 80px 0;
}

.section-alt { background: var(--gray-50); }

.section-title {
  font-size: 32px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 12px;
  color: var(--gray-900);
}

.section-subtitle {
  font-size: 16px;
  color: var(--gray-500);
  text-align: center;
  max-width: 560px;
  margin: 0 auto 48px;
  line-height: 1.6;
}

/* === Features Grid === */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  padding: 32px;
  border-radius: var(--radius-xl);
  background: #fff;
  border: 1px solid var(--gray-200);
  transition: box-shadow 0.2s, transform 0.2s;
}

.feature-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-lg);
  background: var(--c-primary-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
  color: var(--c-primary);
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--gray-900);
}

.feature-card p {
  font-size: 14px;
  color: var(--gray-500);
  line-height: 1.7;
}

/* === Steps === */
.steps {
  display: flex;
  flex-direction: column;
  gap: 32px;
  max-width: 700px;
  margin: 0 auto;
}

.step {
  display: flex;
  gap: 20px;
  align-items: flex-start;
}

.step-number {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--c-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 16px;
  flex-shrink: 0;
}

.step-content h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--gray-900);
}

.step-content p {
  font-size: 14px;
  color: var(--gray-500);
  line-height: 1.6;
}

/* === Calculator === */
.calculator-card {
  max-width: 800px;
  margin: 0 auto;
  padding: 48px;
  border-radius: var(--radius-xl);
  border: 2px solid var(--gray-200);
  text-align: center;
  background: #fff;
}

.calculator-card h3 {
  font-size: 24px;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 12px;
}

.calculator-card p {
  font-size: 14px;
  color: var(--gray-500);
  margin-bottom: 24px;
}

/* === Calculator Form === */
.calc-form { text-align: left; }

.calc-form-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-bottom: 24px;
}

.calc-field {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.calc-field label {
  font-size: 12px;
  font-weight: 600;
  color: var(--gray-600);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.calc-field input {
  padding: 10px 12px;
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 14px;
  color: var(--gray-900);
  background: #fff;
  transition: border-color 0.15s;
}

.calc-field input:focus {
  outline: none;
  border-color: var(--c-primary);
  box-shadow: 0 0 0 3px var(--c-primary-bg);
}

.calc-submit { width: 100%; margin-top: 8px; }

.calc-submit:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

/* === Calculator Results === */
.calc-result {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid var(--gray-200);
}

.calc-result-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.calc-metric {
  padding: 20px;
  border-radius: var(--radius-lg);
  background: var(--gray-50);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.calc-metric-current { background: var(--gray-50); }
.calc-metric-new { background: #fefce8; }
.calc-metric-savings { background: #ecfdf5; }
.calc-metric-payback { background: var(--c-primary-bg); }
.calc-metric-percent { background: #faf5ff; }

.calc-metric-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--gray-500);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.calc-metric-value {
  font-size: 24px;
  font-weight: 700;
  color: var(--gray-900);
}

.calc-metric-savings .calc-metric-value { color: var(--c-success); }
.calc-metric-percent .calc-metric-value { color: var(--c-primary); }

/* === Anchor offset for sticky topbar === */
.section[id] {
  scroll-margin-top: 80px;
}

/* === Demo CTA === */
.cta-section {
  text-align: center;
}

/* === Footer === */
.landing-footer {
  margin-top: auto;
  padding: 24px 32px;
  border-top: 1px solid var(--gray-200);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: var(--gray-400);
}

.landing-footer strong {
  color: var(--gray-600);
  font-weight: 600;
}

/* === Responsive === */
@media (max-width: 768px) {
  .hero h1 { font-size: 36px; }
  .hero p { font-size: 16px; }
  .hero-stats { flex-direction: column; gap: 24px; }
  .features-grid { grid-template-columns: 1fr; }
  .container { padding: 0 20px; }
  .landing-topbar { padding: 0 20px; }
  .landing-topbar-nav { display: none; }
  .calculator-card { padding: 24px; }
  .calc-form-grid { grid-template-columns: 1fr 1fr; }
  .calc-result-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 480px) {
  .calc-form-grid { grid-template-columns: 1fr; }
  .calc-result-grid { grid-template-columns: 1fr; }
}