:root {
  --bg: #0b1c2e;
  --bg-alt: #020617;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --accent: #2ee6ff;
  --card: #020617;
  --border: #1f2937;
}

:root[data-theme='light'] {
  --bg: #f5f7fa;
  --bg-alt: #ffffff;
  --text: #0b1c2e;
  --muted: #4b5563;
  --accent: #0ea5e9;
  --card: #ffffff;
  --border: #e5e7eb;
}

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

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Inter", sans-serif;
  background: var(--bg);
  color: var(--text);
}

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

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2.5rem;
  background: var(--bg-alt);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-mark {
  width: 32px;
  height: 32px;
  border-radius: 999px;
  background: var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #020617;
  font-size: 0.9rem;
  font-weight: 700;
}

.logo-text {
  font-weight: 600;
  letter-spacing: 0.06em;
  font-size: 0.95rem;
  text-transform: uppercase;
}

.main-nav {
  display: flex;
  gap: 1.25rem;
  font-size: 0.92rem;
}

.main-nav a {
  position: relative;
  padding-bottom: 0.15rem;
}

.main-nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: 2px;
  width: 0;
  background: var(--accent);
  transition: width 0.18s ease;
}

.main-nav a:hover::after {
  width: 100%;
}

.theme-toggle {
  border-radius: 999px;
  padding: 0.35rem 0.8rem;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
  font-size: 0.75rem;
}

.hero {
  padding: 5rem 1.5rem 4rem;
  text-align: center;
}

.hero-inner {
  max-width: 820px;
  margin: 0 auto;
}

.hero-title {
  font-size: clamp(2.6rem, 4vw, 3.4rem);
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--muted);
  max-width: 640px;
  margin: 0 auto 2.4rem;
}

.hero-actions {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.btn {
  border-radius: 999px;
  padding: 0.85rem 1.9rem;
  font-weight: 600;
  font-size: 0.94rem;
  border: 1px solid transparent;
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: #020617;
  border-color: var(--accent);
}

.btn-outline {
  background: transparent;
  border-color: var(--border);
  color: var(--text);
}

.section {
  padding: 3.5rem 1.5rem;
}

.section-inner {
  max-width: 1100px;
  margin: 0 auto;
}

.section-title {
  font-size: 2rem;
  text-align: center;
  margin-bottom: 0.6rem;
}

.section-description {
  text-align: center;
  color: var(--muted);
  max-width: 620px;
  margin: 0 auto 2.4rem;
  font-size: 0.96rem;
}

.grid {
  display: grid;
  gap: 1.75rem;
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.card {
  background: var(--card);
  border-radius: 1rem;
  border: 1px solid var(--border);
  padding: 1.7rem;
  box-shadow: 0 18px 45px rgba(15,23,42,0.45);
}

.card-title {
  font-size: 1.15rem;
  margin-bottom: 0.4rem;
}

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

.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.6rem 1.5rem;
  text-align: center;
  font-size: 0.85rem;
  background: var(--bg-alt);
  color: var(--muted);
}

/* Form */
.form {
  max-width: 620px;
  margin: 0 auto;
}

.form-row {
  margin-bottom: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.form label {
  font-size: 0.86rem;
  font-weight: 500;
}

.form input,
.form textarea {
  padding: 0.7rem 0.9rem;
  border-radius: 0.65rem;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  font-size: 0.95rem;
}

.form textarea {
  min-height: 140px;
  resize: vertical;
}

/* Responsive */
@media (max-width: 900px) {
  .site-header {
    flex-wrap: wrap;
    gap: 0.75rem;
    padding: 0.75rem 1.25rem;
  }
  .main-nav {
    flex-wrap: wrap;
    justify-content: center;
    flex: 1 0 100%;
  }
}