/* Zelmit design tokens — Brand Guide v0.1 */
:root {
  /* Brand constants (theme-invariant) */
  --zelmit-blue: #1e88e5;
  --deep-blue: #1565c0;
  --navy: #0b1220;
  --white: #ffffff;
  --light-gray: #e5e7eb;
  --dark-gray: #374151;
  --gradient: linear-gradient(135deg, #29b6f6, #1565c0);
  --font-sans: "Inter", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
  --max-width: 64rem;

  /* Semantic tokens — light theme (default) */
  --bg: var(--white);
  --text: var(--dark-gray);
  --heading: var(--navy);
  --muted: var(--dark-gray);
  --border: var(--light-gray);
  --border-strong: var(--dark-gray);
  --surface: color-mix(in srgb, var(--light-gray) 25%, var(--white));
  --accent: var(--zelmit-blue);
  --accent-gradient: var(--gradient);
  --on-accent: var(--white);
}

[data-theme="dark"] {
  /* Semantic tokens — dark theme. Diverges from the brand navy on purpose:
     petrol (teal-tinted) background with luminance-based surface hierarchy
     and a cyan accent that harmonizes with the blue brand logo. */
  --bg: #0e191c;
  --text: #d4d4d8;
  --heading: #fafafa;
  --muted: #a1a1aa;
  --border: color-mix(in srgb, var(--white) 10%, transparent);
  --border-strong: color-mix(in srgb, var(--white) 22%, transparent);
  --surface: #16262a;
  --accent: #22d3ee;
  --accent-gradient: linear-gradient(135deg, #22d3ee, #0e7490);
  --on-accent: #062227;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.6;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 1.5rem;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--heading);
}

.brand-mark {
  width: 2rem;
  height: 2rem;
}

.brand-name {
  font-weight: 600;
  letter-spacing: 0.35em;
  font-size: 1rem;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.site-nav a {
  color: var(--text);
  text-decoration: none;
  font-size: 0.95rem;
}

.site-nav a:hover {
  color: var(--heading);
}

.nav-cta {
  padding: 0.4rem 0.9rem;
  border: 1px solid var(--accent);
  border-radius: 0.5rem;
}

.lang-switch,
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 2rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: none;
  color: var(--text);
  cursor: pointer;
}

.lang-switch {
  padding: 0 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-decoration: none;
}

.theme-toggle {
  width: 2rem;
  padding: 0;
}

.lang-switch:hover,
.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--heading);
}

.theme-icon-sun {
  display: none;
}

[data-theme="dark"] .theme-icon-sun {
  display: inline-flex;
}

[data-theme="dark"] .theme-icon-moon {
  display: none;
}

/* Hero */
.hero {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 6rem 1.5rem 4rem;
  text-align: center;
}

[data-theme="dark"] .hero {
  /* subtle cyan glow behind the hero; luminance depth without imagery */
  background: radial-gradient(60% 50% at 50% 0%, rgba(34, 211, 238, 0.06), transparent 70%);
}

.hero h1 {
  margin: 0;
  color: var(--heading);
  font-size: clamp(2.2rem, 6vw, 3.75rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.gradient-text {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-sub {
  max-width: 44rem;
  margin: 1.5rem auto 0;
  font-size: 1.125rem;
  color: var(--text);
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-top: 2.5rem;
  flex-wrap: wrap;
}

.hero-tag {
  margin-top: 3rem;
}

.hero-tag code {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  border: 1px solid color-mix(in srgb, var(--accent) 40%, transparent);
  border-radius: 0.5rem;
  padding: 0.4rem 0.8rem;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 0.5rem;
  font-weight: 600;
  text-decoration: none;
  font-size: 1rem;
}

.btn-primary {
  background: var(--accent-gradient);
  color: var(--on-accent);
}

.btn-primary:hover {
  filter: brightness(1.1);
}

.btn-ghost {
  color: var(--heading);
  border: 1px solid var(--border-strong);
}

.btn-ghost:hover {
  border-color: var(--accent);
}

/* Sections */
.section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 4rem 1.5rem;
}

.section h2 {
  margin: 0 0 2rem;
  color: var(--heading);
  font-size: 2rem;
  letter-spacing: -0.01em;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(13.5rem, 1fr));
  gap: 1.25rem;
}

.card {
  padding: 1.5rem;
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  background: var(--surface);
}

.card h3 {
  margin: 0 0 0.5rem;
  color: var(--heading);
  font-size: 1.1rem;
}

.card p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--text);
}

.feature-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(13.5rem, 1fr));
  gap: 0.75rem 2rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.feature-list li {
  padding-left: 1.5rem;
  position: relative;
}

.feature-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 0.55rem;
  height: 0.55rem;
  border-radius: 2px;
  background: var(--accent-gradient);
}

.section-contact {
  text-align: center;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 2rem 1.5rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--muted);
}