:root {
  --bg: #f3f4f6;
  --surface: #ffffff;
  --text: #1f2937;
  --text-strong: #111827;
  --muted: #6b7280;
  --border: #e5e7eb;
  --border-strong: #d1d5db;
  --accent: #3498db;
  --accent-dark: #2980b9;
  --accent-soft: rgba(52, 152, 219, 0.15);
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-hover: 0 6px 18px rgba(17, 24, 39, 0.1);
  --radius: 10px;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.5;
}

h1,
h2,
h3 {
  color: var(--text-strong);
  line-height: 1.25;
}

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

:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px var(--accent-soft);
  border-radius: 6px;
}

/* ---------- Top bar ---------- */
.app-topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.app-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text-strong);
  text-decoration: none;
  min-width: 0;
}

.app-brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  flex: none;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
}

.app-brand-text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.app-brand-name {
  font-size: 18px;
  font-weight: 700;
  white-space: nowrap;
}

.app-brand-sub {
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}

.app-user {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: none;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
  font-family: inherit;
  line-height: 1.2;
  padding: 9px 14px;
  text-decoration: none;
  text-align: center;
  transition: background 0.15s ease, box-shadow 0.15s ease;
}

.btn:hover {
  background: var(--accent-dark);
}

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

.btn-secondary {
  background: #95a5a6;
}

.btn-secondary:hover {
  background: #7f8c8d;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 13px;
}

/* ---------- Auth state ---------- */
.is-hidden {
  display: none !important;
}

.user-chip {
  display: inline-block;
  max-width: 220px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  color: var(--ink);
  font-size: 13px;
}

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

/* ---------- Page / hero ---------- */
.page {
  flex: 1 0 auto;
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px 20px 60px;
}

.hero {
  padding: 40px 0 32px;
  max-width: 720px;
}

.hero-title {
  font-size: 34px;
  font-weight: 700;
  margin: 0 0 14px;
}

.hero-lead {
  margin: 0 0 24px;
  font-size: 17px;
  color: var(--muted);
}

.hero-cta {
  display: inline-block;
}

/* ---------- Subsystems ---------- */
.section-title {
  font-size: 19px;
  font-weight: 700;
  margin: 0 0 16px;
}

.subsystems-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}

.subsystem-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  padding: 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: box-shadow 0.15s ease, border-color 0.15s ease;
}

.subsystem-card:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-hover);
}

.subsystem-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin-bottom: 14px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent-dark);
  flex: none;
}

.subsystem-title {
  font-size: 18px;
  font-weight: 700;
  margin: 0 0 8px;
}

.subsystem-badge {
  margin-bottom: 8px;
}

.subsystem-desc {
  flex: 1 1 auto;
  margin: 0 0 18px;
  font-size: 14px;
  color: var(--muted);
}

.subsystem-open {
  align-self: flex-start;
  min-height: 32px;
}

/* ---------- Badge ---------- */
.badge {
  display: inline-block;
  color: #fff;
  background: var(--accent);
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  white-space: nowrap;
}

/* ---------- Empty / muted ---------- */
.empty {
  text-align: center;
  color: #9ca3af;
  padding: 48px 16px;
}

.muted {
  color: var(--muted);
  font-size: 14px;
}

.noscript-note {
  margin-top: 16px;
}

/* ---------- Footer ---------- */
.site-footer {
  flex: none;
  padding: 18px 20px;
  border-top: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

.site-footer p {
  margin: 0;
}

/* ---------- Responsive ---------- */
@media (max-width: 767px) {
  .app-brand-sub {
    display: none;
  }

  .hero {
    padding: 28px 0 24px;
  }

  .hero-title {
    font-size: 25px;
  }

  .hero-lead {
    font-size: 15px;
  }

  .hero-cta {
    display: block;
    width: 100%;
  }

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