:root {
  --bg: #f5f6f8;
  --panel: #ffffff;
  --border: #e2e5ea;
  --text: #1f2430;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --danger: #dc2626;
  --success: #16a34a;
  --warn: #d97706;
  --radius: 8px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

header.topbar {
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

header.topbar .brand { font-weight: 700; font-size: 17px; }
header.topbar nav a { margin-right: 16px; color: var(--text); font-size: 14px; }
header.topbar .userbox { font-size: 13px; color: var(--muted); }
header.topbar .userbox a { margin-left: 10px; }

main.container {
  max-width: 1000px;
  margin: 24px auto;
  padding: 0 20px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 20px;
}

h1 { font-size: 22px; margin: 0 0 16px; }
h2 { font-size: 17px; margin: 0 0 12px; }

table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); font-size: 14px; }
th { color: var(--muted); font-weight: 600; font-size: 12px; text-transform: uppercase; }
tr:hover td { background: #fafbfc; }

.btn {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 8px 14px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 14px;
}
.btn:hover { background: var(--primary-dark); text-decoration: none; }
.btn.secondary { background: #fff; color: var(--text); border: 1px solid var(--border); }
.btn.danger { background: var(--danger); }
.btn.small { padding: 4px 10px; font-size: 13px; }

.form-group { margin-bottom: 14px; }
.form-group label { display: block; margin-bottom: 4px; font-size: 13px; color: var(--muted); }
.form-group input, .form-group select, .form-group textarea {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  font-family: inherit;
}
.form-row { display: flex; gap: 14px; }
.form-row .form-group { flex: 1; }

.alert { padding: 10px 14px; border-radius: 6px; margin-bottom: 16px; font-size: 14px; }
.alert.error { background: #fef2f2; color: var(--danger); border: 1px solid #fecaca; }
.alert.success { background: #f0fdf4; color: var(--success); border: 1px solid #bbf7d0; }

.badge { display: inline-block; padding: 2px 8px; border-radius: 999px; font-size: 12px; font-weight: 600; }
.badge.draft { background: #f1f5f9; color: #475569; }
.badge.sent { background: #dbeafe; color: #1d4ed8; }
.badge.paid { background: #dcfce7; color: #15803d; }
.badge.overdue { background: #fee2e2; color: #b91c1c; }
.badge.void { background: #f1f5f9; color: #94a3b8; }
.badge.active { background: #dcfce7; color: #15803d; }
.badge.suspended { background: #fee2e2; color: #b91c1c; }
.badge.open { background: #dbeafe; color: #1d4ed8; }
.badge.pending { background: #fef9c3; color: #a16207; }
.badge.closed { background: #f1f5f9; color: #64748b; }

.stat-grid { display: flex; gap: 16px; margin-bottom: 20px; }
.stat { flex: 1; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; }
.stat .num { font-size: 26px; font-weight: 700; }
.stat .label { color: var(--muted); font-size: 13px; }

.msg { border: 1px solid var(--border); border-radius: 6px; padding: 10px 14px; margin-bottom: 10px; }
.msg .meta { font-size: 12px; color: var(--muted); margin-bottom: 4px; }
.msg.admin { background: #eff6ff; }
.msg.customer { background: #fafafa; }

.toolbar { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; }
.muted { color: var(--muted); }
.center-box { max-width: 380px; margin: 80px auto; }