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

:root {
  --accent: #00e1b7;
  --dark: #111111;
  --text: #333333;
  --muted: #666666;
  --light: #f8f8f8;
  --white: #ffffff;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Roboto', sans-serif;
  color: var(--text);
  line-height: 1.6;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ── NAV ────────────────────────────────────────────── */

header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--white);
  z-index: 100;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

nav {
  display: flex;
  align-items: center;
  height: 64px;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

.logo img {
  display: block;
}

/* ── HERO ───────────────────────────────────────────── */

.hero {
  padding: 160px 0 100px;
  text-align: center;
  background: var(--white);
}

.hero h1 {
  font-size: clamp(2.4rem, 6vw, 4.5rem);
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 20px;
  line-height: 1.1;
}

.hero > .container > p {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  color: var(--muted);
  margin-bottom: 40px;
  max-width: 580px;
  margin-left: auto;
  margin-right: auto;
}

/* ── BUTTONS ────────────────────────────────────────── */

.btn-primary {
  display: inline-block;
  background: var(--accent);
  color: var(--dark);
  border: none;
  padding: 16px 40px;
  font-size: 1rem;
  font-weight: 500;
  font-family: inherit;
  border-radius: 4px;
  cursor: pointer;
  transition: opacity 0.2s;
  text-decoration: none;
}

.btn-primary:hover,
.btn-primary:focus-visible {
  opacity: 0.85;
  outline: none;
}

/* ── HOW IT WORKS ───────────────────────────────────── */

.how-it-works {
  padding: 100px 0;
  background: var(--light);
}

.how-it-works h2 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 60px;
  text-align: center;
}

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 32px;
}

.feature {
  padding: 36px 32px;
  background: var(--white);
  border-radius: 8px;
  border: 1px solid rgba(0, 0, 0, 0.06);
}

.feature-num {
  display: block;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.08em;
  margin-bottom: 14px;
}

.feature h3 {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 10px;
}

.feature p {
  color: var(--muted);
  font-size: 0.95rem;
}

/* ── TAGLINE ────────────────────────────────────────── */

.tagline {
  padding: 90px 0;
  text-align: center;
  background: var(--dark);
}

.tagline p {
  font-size: clamp(1.4rem, 3vw, 2rem);
  font-weight: 300;
  color: var(--white);
}

/* ── CTA ────────────────────────────────────────────── */

.cta {
  padding: 100px 0;
  text-align: center;
  background: var(--white);
}

.cta h2 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 14px;
}

.cta > .container > p {
  color: var(--muted);
  margin-bottom: 36px;
  font-size: 1.05rem;
}

/* ── MODAL ──────────────────────────────────────────── */

.modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal.open {
  display: flex;
}

.modal-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
}

.modal-content {
  position: relative;
  background: var(--white);
  border-radius: 12px;
  padding: 48px;
  max-width: 480px;
  width: 90%;
  z-index: 1;
}

.modal-close {
  position: absolute;
  top: 14px;
  right: 20px;
  background: none;
  border: none;
  font-size: 2rem;
  cursor: pointer;
  color: #aaa;
  line-height: 1;
  transition: color 0.15s;
}

.modal-close:hover {
  color: var(--dark);
}

.modal-content h2 {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 8px;
}

.modal-sub {
  color: var(--muted);
  margin-bottom: 24px;
}

#signup-form {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

#signup-form input {
  width: 100%;
  padding: 14px 16px;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 1rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s;
}

#signup-form input:focus {
  border-color: var(--accent);
}

#signup-form .btn-primary {
  width: 100%;
  padding: 14px;
  margin-top: 4px;
}

.form-success {
  text-align: center;
  color: var(--accent);
  font-weight: 500;
  margin-top: 20px;
  font-size: 1.05rem;
}

/* ── FOOTER ─────────────────────────────────────────── */

footer {
  background: var(--light);
  padding: 40px 0;
  border-top: 1px solid #ebebeb;
}

footer .container {
  display: flex;
  align-items: center;
  gap: 20px;
}

footer p {
  color: #aaa;
  font-size: 0.875rem;
}

/* ── RESPONSIVE ─────────────────────────────────────── */

@media (max-width: 640px) {
  .hero {
    padding: 120px 0 80px;
  }

  .how-it-works,
  .cta {
    padding: 70px 0;
  }

  .tagline {
    padding: 60px 0;
  }

  .modal-content {
    padding: 36px 24px;
  }

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