:root {
  --bg: #0f1219;
  --bg-surface: #181d27;
  --bg-card: #1e2433;
  --text: #e8eaf0;
  --text-muted: #8b93a7;
  --accent: #4fc3f7;
  --accent-hover: #81d4fa;
  --border: #2a3145;
  --radius: 8px;
  --max-width: 1100px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  overflow-x: hidden;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* Focus styles */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

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

/* ===== HEADER ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 18, 25, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-weight: 600;
  font-size: 18px;
}

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

nav {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 15px;
  transition: color 0.2s;
}

nav a:hover,
nav a:focus {
  color: var(--accent);
}

/* ===== HERO ===== */
.hero {
  padding: 100px 0 80px;
  text-align: left;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 24px;
}

.hero-sub {
  font-size: 1.125rem;
  color: var(--text-muted);
  max-width: 640px;
  margin-bottom: 36px;
}

.btn-primary {
  display: inline-block;
  padding: 14px 28px;
  background: var(--accent);
  color: var(--bg);
  text-decoration: none;
  font-weight: 600;
  font-size: 16px;
  border-radius: var(--radius);
  transition: background 0.2s, transform 0.15s;
}

.btn-primary:hover,
.btn-primary:focus {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

/* ===== ABOUT ===== */
.about {
  padding: 80px 0;
  background: var(--bg-surface);
}

.about h2 {
  font-size: 2rem;
  margin-bottom: 32px;
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  align-items: center;
}

.about-text p {
  color: var(--text-muted);
  margin-bottom: 16px;
  text-align: left;
}

.about-text p:last-child {
  margin-bottom: 0;
}

.about-visual {
  display: flex;
  justify-content: center;
}

.parallax-diagram {
  width: 100%;
  max-width: 220px;
  height: auto;
}

@media (min-width: 768px) {
  .about-grid {
    grid-template-columns: 2fr 1fr;
  }
}

/* ===== SERVICES ===== */
.services {
  padding: 80px 0;
}

.services h2 {
  font-size: 2rem;
  margin-bottom: 40px;
}

.services-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.service-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  transition: border-color 0.2s, transform 0.15s;
}

.service-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.service-icon {
  margin-bottom: 16px;
}

.service-card h3 {
  font-size: 1.25rem;
  margin-bottom: 12px;
}

.service-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
  text-align: left;
}

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

/* ===== CONTACT ===== */
.contact {
  padding: 80px 0;
  background: var(--bg-surface);
  text-align: center;
}

.contact h2 {
  font-size: 2rem;
  margin-bottom: 16px;
}

.contact p {
  color: var(--text-muted);
  margin-bottom: 28px;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
  text-align: left;
}

.contact .btn-primary {
  font-size: 16px;
}

/* ===== FOOTER ===== */
.site-footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  text-align: center;
}

.site-footer p {
  color: var(--text-muted);
  font-size: 14px;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 600px) {
  .site-header .container {
    flex-wrap: wrap;
    height: auto;
    padding-top: 12px;
    padding-bottom: 12px;
    gap: 6px;
  }

  .logo {
    font-size: 16px;
    width: 100%;
  }

  nav {
    gap: 20px;
    width: 100%;
  }

  nav a {
    font-size: 14px;
  }
}

@media (max-width: 480px) {
  .hero {
    padding: 60px 0 50px;
  }

  .about,
  .services,
  .contact {
    padding: 60px 0;
  }

  .container {
    padding: 0 16px;
  }

  .service-card {
    padding: 24px 20px;
  }
}