6:  --sidebar-w: 240px;
49:  width: var(--sidebar-w); background: var(--sidebar-bg); color: var(--sidebar-text);
76:.main { flex: 1; margin-left: var(--sidebar-w); display: flex; flex-direction: column; min-width: 0; }
/* ============================================================
   Bulk Gmail Mailer — Design System
   Professional admin UI: dark sidebar, light content, responsive
   ============================================================ */
:root {
  --sidebar-w: 240px;
  --bg: #f4f6fa;
  --surface: #ffffff;
  --border: #e3e8f0;
  --text: #1e2536;
  --muted: #6b7590;
  --primary: #2563eb;
  --primary-dk: #1e40af;
  --primary-lt: #eff6ff;
  --green: #16a34a;
  --green-lt: #f0fdf4;
  --red: #dc2626;
  --red-lt: #fef2f2;
  --amber: #d97706;
  --amber-lt: #fffbeb;
  --violet: #7c3aed;
  --violet-lt: #f5f3ff;
  --sidebar-bg: #101828;
  --sidebar-text: #98a2b3;
  --sidebar-active: #1f2a44;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(16, 24, 40, .08), 0 1px 2px rgba(16, 24, 40, .04);
  --shadow-lg: 0 10px 30px rgba(16, 24, 40, .14);
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font: 14px/1.55 -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg); color: var(--text);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1 { font-size: 22px; font-weight: 700; letter-spacing: -.02em; }