/* ===== Design tokens (v3 corporate-industrial) ===== */
:root {
  /* Marka */
  --color-primary:        #0E4C81;
  --color-primary-hover:  #0A3A66;
  --color-primary-light:  #E6EEF6;

  /* Yüzey */
  --bg-page:    #F4F6F8;
  --bg-surface: #FFFFFF;
  --bg-muted:   #EEF2F5;
  --bg-utility: #1F2933;

  /* Metin */
  --text-primary:   #1F2933;
  --text-secondary: #4B5563;
  --text-muted:     #6B7280;
  --text-on-dark:   #E5E7EB;

  /* Çizgi */
  --border-light:  #E5E7EB;
  --border-medium: #D1D5DB;
  --border-strong: #9CA3AF;

  /* Anlam */
  --color-success: #047857;  --color-success-bg: #D1FAE5;
  --color-warning: #B45309;  --color-warning-bg: #FEF3C7;
  --color-danger:  #B91C1C;  --color-danger-bg:  #FEE2E2;
  --color-info:    #0369A1;  --color-info-bg:    #DBEAFE;

  /* Layout sabitleri */
  --utility-h: 28px;
  --topbar-h:  56px;
  --subbar-h:  36px;
  --sidebar-w: 240px;

  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;

  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.10);

  --transition: 150ms ease;

  --font-sans: 'Source Sans 3', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Menlo, Consolas, monospace;
}

/* ===== Reset ===== */
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.5;
  color: var(--text-primary);
  background: var(--bg-page);
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
button { font-family: inherit; cursor: pointer; }

/* ===== Utility bar ===== */
.utility-bar {
  height: var(--utility-h);
  background: var(--bg-utility);
  color: var(--text-on-dark);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  font-size: 12px;
}
.utility-brand { font-weight: 500; letter-spacing: 0.02em; }
.utility-user { color: var(--text-on-dark); opacity: 0.85; }

/* ===== Topbar ===== */
.topbar {
  height: var(--topbar-h);
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 16px;
  position: sticky;
  top: var(--utility-h);
  z-index: 30;
}
.hamburger {
  display: none;
  background: transparent;
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  width: 36px; height: 36px;
  align-items: center; justify-content: center;
  color: var(--text-primary);
}
.topbar-brand { display: flex; align-items: center; gap: 10px; }
.topbar-logo {
  background: var(--color-primary);
  color: white;
  font-weight: 700;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  letter-spacing: 0.04em;
}
.topbar-title { font-weight: 600; font-size: 15px; }
.topbar-nav { display: flex; gap: 2px; flex: 1; margin-left: 16px; }
.topbar-nav a {
  padding: 8px 12px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  transition: background var(--transition), color var(--transition);
}
.topbar-nav a:hover { background: var(--bg-muted); color: var(--text-primary); text-decoration: none; }
.topbar-nav a.active { color: var(--color-primary); background: var(--color-primary-light); }

/* ===== Subbar ===== */
.subbar {
  height: var(--subbar-h);
  background: var(--bg-muted);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  padding: 0 16px;
  font-size: 13px;
  color: var(--text-secondary);
}

/* ===== Content ===== */
.content {
  padding: 24px 16px;
  max-width: 1200px;
  margin: 0 auto;
}

/* ===== Typography helpers ===== */
h1, h2, h3 { color: var(--text-primary); margin: 0 0 12px; font-weight: 600; }
h1 { font-size: clamp(22px, 2.4vw, 28px); }
h2 { font-size: clamp(18px, 2vw, 22px); }
h3 { font-size: 16px; }
.muted { color: var(--text-muted); }
.label-tag {
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 600;
}

/* ===== Mobile ===== */
@media (max-width: 900px) {
  .utility-bar { font-size: 11px; padding: 0 12px; }
  .topbar { gap: 8px; padding: 0 12px; }
  .hamburger { display: inline-flex; }
  .topbar-nav { display: none; }
  .content { padding: 16px 12px; }
}

/* ===== A11y ===== */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}