:root {
  --nav-height: 64px;
  --section-bg: #f8f9fa;
  --ink: #212529;
  --muted: #6c757d;
}

html {
  overflow-y: scroll;
}

body {
  padding-top: calc(var(--nav-height) + 16px);
  color: var(--ink);
}

.navbar {
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.08);
}

.navbar-brand {
  font-weight: 600;
  letter-spacing: 0.02em;
}

.section-panel {
  background: var(--section-bg);
  border-radius: 8px;
  padding: 16px;
}

.canvas-frame {
  border: 1px solid #ced4da;
  border-radius: 6px;
  background: #ffffff;
}

.rod-table input {
  max-width: 80px;
  margin: 0 auto;
  text-align: center;
}

.tab-header {
  margin-bottom: 12px;
}

.callout {
  background: #ffffff;
  border: 1px solid #e0e0e0;
  border-radius: 8px;
  padding: 16px;
}

.form-help {
  color: var(--muted);
  font-size: 0.9rem;
}

.error-banner {
  border: 1px solid #dc3545;
  background: #f8d7da;
  color: #842029;
  padding: 8px 12px;
  border-radius: 6px;
  margin-top: 12px;
}