/* ===== Design system ===== */
:root {
  --bg: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --heading: #0f172a;
  --accent-start: #6366f1;
  --accent-end: #8b5cf6;
  --accent-gradient: linear-gradient(135deg, var(--accent-start), var(--accent-end));
  --border: #e2e8f0;
  --radius-sm: 8px;
  --radius: 12px;
  --radius-lg: 16px;
  --font: "DM Sans", -apple-system, BlinkMacSystemFont, sans-serif;
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow: 0 4px 6px -1px rgba(15, 23, 42, 0.07), 0 2px 4px -2px rgba(15, 23, 42, 0.05);
  --shadow-hover: 0 10px 15px -3px rgba(15, 23, 42, 0.08), 0 4px 6px -4px rgba(15, 23, 42, 0.05);
}

/* ===== Reset & base ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

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

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

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ===== Layout ===== */
.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-md);
}

/* ===== Header ===== */
.header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--heading);
}

.header-cta {
  padding: var(--space-xs) var(--space-md);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--heading);
  border-radius: var(--radius);
  transition: background 0.2s, color 0.2s;
}

.header-cta:hover {
  background: var(--border);
  color: var(--heading);
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-family: var(--font);
  font-size: 1rem;
  font-weight: 500;
  border-radius: var(--radius);
  border: none;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.15s, box-shadow 0.2s;
}

.btn:focus-visible {
  outline: 2px solid var(--accent-start);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--accent-gradient);
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  opacity: 0.95;
  box-shadow: var(--shadow);
}

.btn-primary:disabled {
  opacity: 0.7;
  cursor: not-allowed;
}

.btn-secondary {
  background: transparent;
  color: var(--heading);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 85vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3xl) var(--space-md);
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 80% 50% at 50% 0%, rgba(99, 102, 241, 0.06), transparent),
              radial-gradient(ellipse 60% 40% at 80% 60%, rgba(139, 92, 246, 0.04), transparent);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  text-align: center;
}

.hero-title {
  margin: 0 0 var(--space-md);
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--heading);
}

.hero-subtitle {
  margin: 0 0 var(--space-xl);
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
  font-size: 1.25rem;
  color: var(--text-muted);
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  justify-content: center;
}

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

.section-title {
  margin: 0 0 var(--space-xl);
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--heading);
  text-align: center;
}

/* ===== Problem ===== */
.section-problem {
  background: linear-gradient(180deg, rgba(248, 250, 252, 0.8) 0%, var(--bg) 100%);
}

.problem-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
  max-width: 720px;
  margin: 0 auto;
}

@media (min-width: 768px) {
  .problem-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.problem-card {
  padding: var(--space-lg);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s, border-color 0.2s;
}

.problem-card:hover {
  box-shadow: var(--shadow);
  border-color: rgba(99, 102, 241, 0.2);
}

.problem-card-solution {
  border-color: rgba(99, 102, 241, 0.3);
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.04), rgba(139, 92, 246, 0.04));
}

.problem-label {
  display: block;
  margin-bottom: var(--space-xs);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent-start);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.problem-card p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text);
}

/* ===== How it works ===== */
.steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  max-width: 900px;
  margin: 0 auto;
}

@media (min-width: 768px) {
  .steps {
    grid-template-columns: repeat(3, 1fr);
  }
}

.step {
  text-align: center;
  padding: var(--space-lg);
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  margin-bottom: var(--space-md);
  font-size: 1.25rem;
  font-weight: 700;
  color: white;
  background: var(--accent-gradient);
  border-radius: 50%;
}

.step-title {
  margin: 0 0 var(--space-xs);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--heading);
}

.step-desc {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-muted);
}

/* ===== Use cases ===== */
.use-cases-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-lg);
}

@media (min-width: 640px) {
  .use-cases-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .use-cases-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.use-case-card {
  padding: var(--space-lg);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s, border-color 0.2s, transform 0.15s;
}

.use-case-card:hover {
  box-shadow: var(--shadow-hover);
  border-color: rgba(99, 102, 241, 0.2);
  transform: translateY(-2px);
}

.use-case-title {
  margin: 0 0 var(--space-xs);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--heading);
}

.use-case-card p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-muted);
}

/* ===== Safety ===== */
.safety-inner {
  max-width: 640px;
  margin: 0 auto;
  text-align: center;
}

.safety-text {
  margin: 0 0 var(--space-lg);
  font-size: 1.0625rem;
  color: var(--text);
  line-height: 1.7;
}

.trust-cues {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  justify-content: center;
}

.trust-cue {
  padding: var(--space-xs) var(--space-md);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  background: rgba(99, 102, 241, 0.06);
  border-radius: var(--radius);
}

/* ===== Future ===== */
.section-future {
  background: linear-gradient(180deg, var(--bg) 0%, rgba(248, 250, 252, 0.6) 100%);
}

.future-text {
  margin: 0;
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
  font-size: 1.0625rem;
  color: var(--text-muted);
  text-align: center;
  line-height: 1.7;
}

/* ===== Waitlist ===== */
.waitlist-inner {
  max-width: 480px;
  margin: 0 auto;
  text-align: center;
}

.waitlist-subtitle {
  margin: 0 0 var(--space-lg);
  font-size: 1rem;
  color: var(--text-muted);
}

.waitlist-form {
  margin: 0;
}

.form-row {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

@media (min-width: 480px) {
  .form-row {
    flex-direction: row;
  }
}

.waitlist-form input[type="email"] {
  flex: 1;
  min-width: 0;
  padding: 0.75rem 1rem;
  font-family: var(--font);
  font-size: 1rem;
  color: var(--heading);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: border-color 0.2s, box-shadow 0.2s;
}

.waitlist-form input[type="email"]::placeholder {
  color: var(--text-muted);
}

.waitlist-form input[type="email"]:focus {
  outline: none;
  border-color: var(--accent-start);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

.form-message {
  margin: var(--space-sm) 0 0;
  font-size: 0.9375rem;
  min-height: 1.5em;
}

.form-message.success {
  color: #059669;
}

.form-message.error {
  color: #dc2626;
}

/* ===== Footer ===== */
.footer {
  padding: var(--space-xl) var(--space-md);
  border-top: 1px solid var(--border);
  background: var(--bg);
}

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

.footer .logo {
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--heading);
}

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

.footer-nav a {
  font-size: 0.9375rem;
  color: var(--text-muted);
  transition: color 0.2s;
}

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

/* ===== Responsive tweaks ===== */
@media (max-width: 767px) {
  .section {
    padding: var(--space-2xl) 0;
  }

  .hero {
    min-height: 75vh;
    padding: var(--space-2xl) var(--space-md);
  }

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