:root {
  /* Colours — Kidney Tracker blue on calm white */
  --primary: #208AEF;
  --primary-dark: #1668c0;
  --primary-light: #5FB0F7;
  --accent: #34C759;
  --success: #34C759;
  --bg: #FFFFFF;
  --bg-alt: #F4F8FC;
  --bg-dark: #0F1B2A;
  --text: #16202B;
  --text-secondary: #4A5A6A;
  --text-light: #76869A;
  --text-on-dark: #EAF2FB;
  --border: #E2E9F1;
  --border-light: #EFF4F9;

  /* Typography */
  --font-heading: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', 'Helvetica Neue', sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Segoe UI', 'Helvetica Neue', sans-serif;
  --font-mono: 'SF Mono', 'Menlo', monospace;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 2rem;
  --space-lg: 4rem;
  --space-xl: 8rem;

  /* Sizing */
  --max-width: 1140px;
  --max-width-narrow: 760px;
  --header-height: 64px;

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(16, 32, 48, 0.06);
  --shadow-md: 0 4px 14px rgba(16, 32, 48, 0.09);
  --shadow-lg: 0 10px 34px rgba(16, 32, 48, 0.13);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
}

/* ========== RESET & BASE ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; scroll-padding-top: 80px; }

body {
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a { color: var(--primary); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--primary-dark); }

ul, ol { list-style: none; }

button { font-family: inherit; cursor: pointer; border: none; background: none; }

:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 2px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--primary);
  color: #fff;
  padding: 0.75rem 1.25rem;
  border-radius: 0 0 var(--radius-sm) 0;
  z-index: 300;
}
.skip-link:focus { left: 0; color: #fff; }

/* ========== LAYOUT ========== */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-sm);
}
.container--narrow { max-width: var(--max-width-narrow); }

.section { padding: var(--space-lg) 0; }
.section--alt { background: var(--bg-alt); }
.section--dark { background: var(--bg-dark); color: var(--text-on-dark); }

/* ========== TYPOGRAPHY ========== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
}
h1 { font-size: clamp(2rem, 5vw, 3.25rem); }
h2 { font-size: clamp(1.5rem, 4vw, 2.4rem); }
h3 { font-size: clamp(1.2rem, 3vw, 1.6rem); }
h4 { font-size: 1.2rem; }

.section-label {
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--primary);
  margin-bottom: var(--space-xs);
}
.section-title { margin-bottom: var(--space-sm); }
.section-subtitle {
  color: var(--text-secondary);
  font-size: 1.125rem;
  max-width: 660px;
  margin: 0 auto var(--space-md);
}
.text-center { text-align: center; }
.lede { font-size: 1.15rem; color: var(--text-secondary); }

/* ========== HEADER ========== */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  height: var(--header-height);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}
.site-logo {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.0625rem;
  color: var(--text);
}
.site-logo:hover { color: var(--text); }
.site-logo img { width: 28px; height: 28px; border-radius: 7px; }

.nav-links { display: none; gap: var(--space-md); }
.nav-links a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
}
.nav-links a:hover, .nav-links a.active { color: var(--text); }

.nav-cta { display: none; }

.mobile-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px; height: 44px;
  color: var(--text);
}
.mobile-menu-btn svg { width: 24px; height: 24px; }

.mobile-nav {
  position: fixed;
  top: var(--header-height);
  left: 0; right: 0; bottom: 0;
  background: var(--bg);
  z-index: 99;
  display: none;
  flex-direction: column;
  padding: var(--space-md);
  overflow-y: auto;
}
.mobile-nav.is-open { display: flex; }
.mobile-nav a {
  display: block;
  padding: var(--space-sm) 0;
  font-size: 1.125rem;
  font-weight: 500;
  color: var(--text);
  border-bottom: 1px solid var(--border);
}
.mobile-nav .btn { margin-top: var(--space-md); }

/* ========== BUTTONS ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-xl);
  font-size: 1rem;
  font-weight: 600;
  transition: all var(--transition-fast);
  white-space: nowrap;
}
.btn--primary { background: var(--primary); color: #fff; }
.btn--primary:hover { background: var(--primary-dark); color: #fff; transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn--secondary { background: var(--bg-alt); color: var(--text); }
.btn--secondary:hover { background: var(--border); color: var(--text); }
.btn--outline { border: 2px solid var(--primary); color: var(--primary); }
.btn--outline:hover { background: var(--primary); color: #fff; }
.btn--dark { background: var(--text); color: #fff; }
.btn--dark:hover { background: #000; color: #fff; }
.btn--sm { padding: 0.5rem 1rem; font-size: 0.875rem; }
.btn--lg { padding: 1rem 2rem; font-size: 1.125rem; }
.btn svg { width: 20px; height: 20px; }

/* ========== HERO ========== */
.hero {
  padding: calc(var(--header-height) + var(--space-lg)) 0 var(--space-lg);
  text-align: center;
  overflow: hidden;
}
.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.375rem 1rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
}
.hero__badge svg { width: 16px; height: 16px; }
.hero__title { max-width: 820px; margin: 0 auto var(--space-sm); }
.hero__title .highlight {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero__subtitle {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto var(--space-md);
}
.hero__actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-sm);
}
.hero__note { font-size: 0.8125rem; color: var(--text-light); }
.hero__visual { max-width: 960px; margin: var(--space-lg) auto 0; }

/* ========== DEVICE FRAME ========== */
.device-frame {
  display: block;
  margin: 0 auto;
  max-width: 280px;
  width: 100%;
  border: 10px solid #1c1c1e;
  border-radius: 38px;
  box-shadow: 0 24px 60px rgba(16, 32, 48, 0.20);
  overflow: hidden;
  background: #1c1c1e;
}
.device-frame img { display: block; width: 100%; height: auto; border-radius: 28px; }

.shot-browser {
  max-width: 880px;
  margin: 0 auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  border: 1px solid var(--border);
}
.shot-browser img { width: 100%; height: auto; display: block; }

.phone-row {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
  max-width: 640px;
  margin: var(--space-md) auto 0;
}
@media (min-width: 768px) {
  .phone-row { grid-template-columns: repeat(4, 1fr); max-width: 100%; gap: var(--space-sm); }
}

/* ========== STATS ========== */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
  max-width: 820px;
  margin: 0 auto;
}
.stat-item { text-align: center; }
.stat-item__number {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: var(--space-xs);
}
.stat-item__label { font-size: 0.9375rem; color: var(--text-secondary); font-weight: 500; }

/* ========== FEATURES GRID ========== */
.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}
.feature-card {
  padding: var(--space-md);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: all var(--transition-base);
}
.feature-card:hover { border-color: var(--primary); box-shadow: var(--shadow-md); transform: translateY(-2px); }
.feature-card__icon {
  width: 48px; height: 48px;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-alt);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-sm);
}
.feature-card__icon svg { width: 26px; height: 26px; color: var(--primary); }
.feature-card__title { margin-bottom: var(--space-xs); }
.feature-card__desc { color: var(--text-secondary); font-size: 0.9375rem; }

/* ========== STEPS ========== */
.steps-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
  max-width: 1000px;
  margin: 0 auto;
}
.step-card { text-align: center; padding: var(--space-md); }
.step-card__number {
  display: inline-flex; align-items: center; justify-content: center;
  width: 48px; height: 48px; border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: #fff; font-size: 1.25rem; font-weight: 700;
  margin-bottom: var(--space-sm);
}
.step-card__title { margin-bottom: var(--space-xs); }
.step-card__desc { color: var(--text-secondary); font-size: 0.9375rem; max-width: 320px; margin: 0 auto; }

/* ========== WALKTHROUGH ========== */
.walkthrough { display: flex; flex-direction: column; gap: var(--space-xl); margin-top: var(--space-lg); }
.walkthrough__row { display: grid; grid-template-columns: 1fr; gap: var(--space-md); align-items: center; }
.walkthrough__copy { max-width: 480px; }
.walkthrough__step {
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; border-radius: 50%;
  background: var(--primary); color: #fff; font-weight: 700; font-size: 1rem;
  margin-bottom: var(--space-xs);
}
.walkthrough__title { font-size: 1.375rem; font-weight: 700; margin: 0 0 var(--space-xs); }
.walkthrough__desc { color: var(--text-secondary); }
@media (min-width: 768px) {
  .walkthrough__row { grid-template-columns: 1fr 1fr; gap: var(--space-xl); }
  .walkthrough__row:nth-child(even) .walkthrough__shot { order: 2; }
  .walkthrough__row:nth-child(even) .walkthrough__copy { order: 1; }
  .walkthrough__copy { justify-self: center; }
}

/* ========== USE-CASE CARDS ========== */
.usecase-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-sm);
}
.usecase-card {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: var(--space-md);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
}
.usecase-card:hover { border-color: var(--primary); box-shadow: var(--shadow-sm); transform: translateY(-2px); }
.usecase-card__title { font-size: 1.0625rem; font-weight: 700; color: var(--text); }
.usecase-card__desc { font-size: 0.875rem; color: var(--text-secondary); }
@media (min-width: 640px) { .usecase-grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1024px) { .usecase-grid { grid-template-columns: repeat(3, 1fr); } }

/* ========== PROSE (legal + use-case body) ========== */
.prose { max-width: var(--max-width-narrow); margin: 0 auto; }
.prose h2 { margin: var(--space-md) 0 var(--space-sm); }
.prose h3 { margin: var(--space-md) 0 var(--space-xs); }
.prose p { margin-bottom: var(--space-sm); color: var(--text-secondary); line-height: 1.8; }
.prose ul, .prose ol { list-style: disc; padding-left: 1.4rem; margin-bottom: var(--space-sm); }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: var(--space-xs); color: var(--text-secondary); line-height: 1.75; }
.prose strong { color: var(--text); }
.prose a { font-weight: 500; }

/* ========== BREADCRUMB ========== */
.breadcrumb {
  font-size: 0.8125rem;
  color: var(--text-light);
  padding-top: calc(var(--header-height) + var(--space-md));
}
.breadcrumb ol { display: flex; flex-wrap: wrap; gap: 0.375rem; list-style: none; padding: 0; }
.breadcrumb li::after { content: '/'; margin-left: 0.375rem; color: var(--border); }
.breadcrumb li:last-child::after { content: ''; }
.breadcrumb a { color: var(--text-light); }
.breadcrumb a:hover { color: var(--primary); }

/* page hero (subpages) */
.page-hero { padding: var(--space-md) 0 var(--space-md); }
.page-hero h1 { max-width: 820px; }
.page-hero .lede { max-width: 680px; margin-top: var(--space-sm); }

/* ========== DISCLAIMER ========== */
.disclaimer {
  display: flex;
  gap: var(--space-sm);
  align-items: flex-start;
  max-width: var(--max-width-narrow);
  margin: 0 auto;
  padding: var(--space-sm) var(--space-md);
  background: #EBF4FE;
  border: 1px solid #CFE4FB;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}
.disclaimer svg { width: 22px; height: 22px; flex-shrink: 0; color: var(--primary); margin-top: 1px; }
.disclaimer strong { color: var(--text); }

/* ========== CTA BAND ========== */
.cta-band {
  text-align: center;
  padding: var(--space-lg) 0;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: #fff;
}
.cta-band h2 { color: #fff; margin-bottom: var(--space-sm); }
.cta-band p { opacity: 0.92; max-width: 560px; margin: 0 auto var(--space-md); font-size: 1.125rem; }
.cta-band .btn--primary { background: #fff; color: var(--primary-dark); }
.cta-band .btn--primary:hover { background: #fff; color: var(--primary); }
.cta-band .cta-band__note { font-size: 0.8125rem; opacity: 0.85; margin-top: var(--space-sm); }

/* ========== FAQ ========== */
.faq-list { max-width: 740px; margin: 0 auto; }
.faq-item { border-bottom: 1px solid var(--border); }
.faq-item h3 { margin: 0; }
.faq-question {
  display: flex; align-items: center; justify-content: space-between;
  width: 100%; padding: var(--space-sm) 0;
  font-size: 1.0625rem; font-weight: 600; text-align: left;
  color: var(--text); cursor: pointer;
  font-family: var(--font-heading);
}
.faq-question::after {
  content: '+'; font-size: 1.5rem; font-weight: 300;
  color: var(--text-secondary); transition: transform var(--transition-fast);
  flex-shrink: 0; margin-left: var(--space-sm);
}
.faq-item.is-open .faq-question::after { content: '\2212'; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height var(--transition-base); }
.faq-answer__inner { padding: 0 0 var(--space-sm); color: var(--text-secondary); line-height: 1.7; font-size: 0.9375rem; }
.faq-item.is-open .faq-answer { max-height: 800px; }

/* ========== BETA STEPS ========== */
.beta-steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
  max-width: 900px;
  margin: 0 auto;
}
@media (min-width: 768px) { .beta-steps { grid-template-columns: repeat(3, 1fr); } }
.beta-step {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  text-align: center;
}
.beta-step__num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--primary); color: #fff; font-weight: 700; font-size: 1.125rem;
  margin-bottom: var(--space-sm);
}
.beta-step__title { font-size: 1.125rem; font-weight: 700; margin-bottom: var(--space-xs); }
.beta-step__desc { color: var(--text-secondary); font-size: 0.9375rem; margin-bottom: var(--space-sm); }

/* ========== FOOTER ========== */
.site-footer {
  background: var(--bg-dark);
  color: var(--text-on-dark);
  padding: var(--space-lg) 0 var(--space-md);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}
.footer-brand p { color: var(--text-light); font-size: 0.9375rem; margin-top: var(--space-xs); max-width: 320px; }
.footer-brand .site-logo { color: var(--text-on-dark); }
.footer-brand .site-logo:hover { color: #fff; }
.footer-col h4 {
  color: var(--text-on-dark);
  margin-bottom: var(--space-sm);
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.footer-col a { display: block; padding: 0.25rem 0; color: var(--text-light); font-size: 0.9375rem; }
.footer-col a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: var(--space-md);
  display: flex; flex-direction: column; gap: var(--space-sm);
  align-items: center; font-size: 0.8125rem; color: var(--text-light);
}
.footer-disclaimer { max-width: 720px; text-align: center; line-height: 1.6; }
@media (min-width: 768px) {
  .footer-grid { grid-template-columns: 2fr 1fr 1fr 1fr; }
}

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

/* ========== RESPONSIVE ========== */
@media (min-width: 768px) {
  .container { padding: 0 var(--space-md); }
  .section { padding: var(--space-xl) 0; }
  .nav-links { display: flex; }
  .nav-cta { display: inline-flex; }
  .mobile-menu-btn { display: none; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-bottom { }
  .stats-grid { grid-template-columns: repeat(4, 1fr); }
}
@media (min-width: 1024px) {
  .features-grid { grid-template-columns: repeat(3, 1fr); }
  .hero { padding-top: calc(var(--header-height) + var(--space-xl)); padding-bottom: var(--space-xl); }
}

/* ========== REDUCED MOTION ========== */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ---- Website forms (signup + contact) ---- */
.kt-form { display: flex; flex-direction: column; gap: var(--space-xs); }
.kt-form__row { display: flex; gap: var(--space-xs); flex-wrap: wrap; }
.kt-form__row .kt-input { flex: 1 1 220px; }
.kt-input,
.kt-textarea {
  width: 100%;
  padding: 0.7rem 0.9rem;
  font: inherit;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-sizing: border-box;
}
.kt-input:focus,
.kt-textarea:focus { outline: 2px solid var(--primary); outline-offset: 1px; border-color: var(--primary); }
.kt-textarea { min-height: 120px; resize: vertical; }
.kt-field { display: flex; flex-direction: column; gap: 0.35rem; }
.kt-field label { font-weight: 600; font-size: 0.95rem; }
.kt-hp { position: absolute; left: -9999px; width: 1px; height: 1px; overflow: hidden; }
.form-consent { font-size: 0.85rem; color: var(--text-secondary); margin: 0; }
.form-status { font-size: 0.95rem; margin: 0.25rem 0 0; }
.form-status--ok { color: var(--primary-dark); }
.form-status--error { color: #C0392B; }
.signup-band { background: var(--bg-alt); border-radius: var(--radius-lg); padding: var(--space-md); margin-top: var(--space-md); }
.signup-band h3 { margin: 0 0 0.4rem; }
.signup-band p { margin: 0 0 var(--space-xs); color: var(--text-secondary); }
.footer-signup { margin-top: var(--space-sm); max-width: 320px; }
.footer-signup .kt-input { background: rgba(255,255,255,0.08); border-color: rgba(255,255,255,0.25); color: var(--text-on-dark); }
.footer-signup .form-consent { color: var(--text-light); }