body {
  background: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 15px;
  min-height: 100vh;
}

/* ---- Header ---- */
.site-header {
  border-bottom: 1px solid var(--border);
  padding: 0;
  position: sticky;
  top: 0;
  background: var(--bg-primary);
  z-index: 100;
}

.site-header .inner {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.logo {
  font-size: 18px;
  font-weight: 700;
  color: #ffffff;
  letter-spacing: -0.03em;
}

/* ---- Main layout ---- */
.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

main {
  padding: var(--space-8) 0 var(--space-12);
}

/* ---- Hero (step 1) ---- */
.hero {
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
  padding: 80px 0 72px;
}

.hero-title {
  font-size: 42px;
  font-weight: 700;
  letter-spacing: -0.04em;
  color: #ffffff;
  margin-bottom: var(--space-4);
  line-height: 1.1;
}

.hero-sub {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: var(--space-8);
  line-height: 1.65;
}

/* ---- Steps ---- */
.step {
  display: none;
}

.step--active {
  display: block;
}

/* ---- Section ---- */
.section {
  margin-bottom: var(--space-8);
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-4);
}

.section-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.07em;
}

/* ---- Hardware grid ---- */
.hw-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}

.hw-group {
  margin-bottom: var(--space-6);
}

.hw-group-title {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: var(--space-2);
  padding-left: 2px;
}

/* ---- Back nav ---- */
.step-nav {
  margin-bottom: var(--space-5);
}

/* ---- Divider ---- */
.divider {
  border: none;
  border-top: 1px solid var(--border-muted);
  margin: var(--space-6) 0;
}

@media (max-width: 1024px) {
  .hw-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  .site-header .inner {
    padding: 0 var(--space-4);
    height: 48px;
  }

  .container {
    padding: 0 var(--space-4);
  }

  .hero {
    padding: 48px 0 40px;
    text-align: left;
  }

  .hero-title {
    font-size: 28px;
  }

  .hw-grid {
    grid-template-columns: 1fr;
  }

  main {
    padding: var(--space-5) 0 var(--space-8);
  }
}