.signal-grade {
  display: inline-block;
  padding: 0.08rem 0.4rem;
  border-radius: 0.375rem;
  border: 1px solid rgba(255, 255, 255, 0.06);
  font-weight: 100;
  font-size: 0.75rem; /* very small */
  min-width: 2.4rem;
  text-align: center;
  color: var(--app-text);
  background: transparent;
  font-family: 'Courier New', monospace;
  text-transform: uppercase; /* make displayed value all caps */
}

.signal-grade--excellent {
  border-color: #15803d; /* darker green */
  background: rgba(21, 128, 61, 0.14);
  color: #e8fff0;
}

.signal-grade--good {
  border-color: #2563eb; /* darker blue */
  background: rgba(37, 99, 235, 0.12);
}

.signal-grade--fair {
  border-color: #b45309; /* darker amber */
  background: rgba(180, 83, 9, 0.12);
  color: #fff8ea;
}

.signal-grade--poor {
  border-color: #d97706;
  background: rgba(217, 119, 6, 0.12);
}

.signal-grade--critical {
  border-color: #b91c1c; /* darker red */
  background: rgba(185, 28, 28, 0.16);
}

.signal-grade--unknown {
  border-color: rgba(255, 255, 255, 0.06);
  color: var(--app-text-muted);
}