:root {
  --bg:        #08111f;
  --bg-raised: #0e1c30;
  --bg-card:   #0d1f35;
  --border:    #1a3050;
  --accent:    #00b4d8;
  --accent-dk: #0096c7;
  --text:      #ccd8e8;
  --text-dim:  #7a96b4;
  --white:     #f0f7ff;
  --radius:    12px;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.65;
}

.container {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ── Nav ── */
nav {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(8, 17, 31, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.logo {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--white);
  letter-spacing: -0.02em;
}

/* ── Buttons ── */
.btn {
  display: inline-block;
  padding: 12px 26px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.1s;
}
.btn:hover { opacity: 0.88; transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

.btn-primary {
  background: var(--accent);
  color: #000;
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ── Hero ── */
.hero {
  padding: 96px 0 80px;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 800;
  line-height: 1.15;
  color: var(--white);
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.accent { color: var(--accent); }

.hero-sub {
  font-size: 1.15rem;
  color: var(--text-dim);
  max-width: 600px;
  margin: 0 auto 36px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 0;
}

/* ── Tank demo ── */
.tank-demo {
  margin: 60px auto 0;
  max-width: 200px;
}

.tank-outer {
  width: 160px;
  height: 220px;
  margin: 0 auto;
  border: 2px solid var(--border);
  border-radius: 6px 6px 10px 10px;
  overflow: hidden;
  position: relative;
  background: rgba(0, 30, 60, 0.4);
}

.tank-water {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 73%;
  background: linear-gradient(180deg, rgba(0,180,216,0.25) 0%, rgba(0,150,199,0.4) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  animation: swell 4s ease-in-out infinite;
}

@keyframes swell {
  0%, 100% { height: 73%; }
  50%       { height: 75%; }
}

.tank-label {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--white);
  text-align: center;
  z-index: 1;
}
.tank-label span {
  display: block;
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--text-dim);
}

.wave {
  position: absolute;
  top: -18px;
  left: 0;
  right: 0;
  width: 100%;
  height: 20px;
  fill: rgba(0,180,216,0.35);
}

.tank-caption {
  margin-top: 12px;
  font-size: 0.8rem;
  color: var(--text-dim);
}

/* ── How it works ── */
.how-it-works {
  padding: 96px 0;
  background: var(--bg-raised);
}

.how-it-works h2,
.features h2,
.contact h2 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  color: var(--white);
  text-align: center;
  margin-bottom: 56px;
  letter-spacing: -0.02em;
}

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 40px;
}

.step {
  text-align: center;
}

.step-icon {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: rgba(0,180,216,0.12);
  border: 1px solid rgba(0,180,216,0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  color: var(--accent);
}

.step-icon svg {
  width: 26px;
  height: 26px;
}

.step h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 10px;
}

.step p {
  color: var(--text-dim);
  font-size: 0.95rem;
}

/* ── Features ── */
.features {
  padding: 96px 0;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  transition: border-color 0.2s;
}
.feature-card:hover { border-color: rgba(0,180,216,0.4); }

.feature-icon {
  font-size: 1.8rem;
  margin-bottom: 14px;
}

.feature-card h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 0.9rem;
  color: var(--text-dim);
}

/* ── CTA band ── */
.cta-band {
  padding: 72px 0;
  background: linear-gradient(135deg, #062040 0%, #0a2d50 100%);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
  flex-wrap: wrap;
}

.cta-inner h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 10px;
  letter-spacing: -0.02em;
}

.cta-inner p {
  color: var(--text-dim);
  max-width: 500px;
}

/* ── Signup note ── */
.signup-note {
  padding: 48px 0;
  background: rgba(0, 180, 216, 0.05);
  border-top: 1px solid rgba(0, 180, 216, 0.15);
  border-bottom: 1px solid rgba(0, 180, 216, 0.15);
}

.signup-note-inner {
  display: flex;
  align-items: flex-start;
  gap: 20px;
  max-width: 640px;
  margin: 0 auto;
}

.signup-note-icon {
  font-size: 2rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.signup-note-inner h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 8px;
}

.signup-note-inner p {
  font-size: 0.95rem;
  color: var(--text-dim);
}

/* ── Contact ── */
.contact {
  padding: 96px 0;
  text-align: center;
}

.contact-sub {
  color: var(--text-dim);
  font-size: 1.05rem;
  margin-bottom: 48px;
}

.contact-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 48px 40px;
  max-width: 480px;
  margin: 0 auto;
}

.contact-card p {
  margin-bottom: 24px;
  font-size: 1rem;
}

.contact-email {
  font-size: 1.05rem;
  padding: 14px 36px;
}

.contact-note {
  margin-top: 20px;
  font-size: 0.85rem;
  color: var(--text-dim);
}

/* ── Footer ── */
footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-copy {
  font-size: 0.85rem;
  color: var(--text-dim);
}

/* ── Responsive ── */
@media (max-width: 600px) {
  .hero { padding: 64px 0 56px; }
  .how-it-works, .features, .contact { padding: 64px 0; }
  .cta-band { padding: 52px 0; }
  .cta-inner { flex-direction: column; text-align: center; }
  .contact-card { padding: 36px 24px; }
  .btn-primary { width: 100%; text-align: center; }
}