/* Short, opt-in interference. It never intercepts input or moves reading text. */
.signal-interference {
  position: fixed;
  inset: 0;
  z-index: 9990;
  overflow: hidden;
  pointer-events: none;
  background: repeating-linear-gradient(0deg, transparent 0 3px, #00a9b00c 3px 4px);
}
.signal-interference[hidden] { display: none; }
.signal-interference::before {
  content: "";
  position: absolute;
  inset: -24px 0;
  background: linear-gradient(transparent 0 18%, #00d8eb20 18% 19%, transparent 19% 46%, #ea329a1c 46% 47%, transparent 47% 76%, #7f4dff18 76% 78%, transparent 78%);
  box-shadow: inset 2px 0 #00abb7, inset -2px 0 #bd2e87;
}
.signal-badge {
  position: absolute;
  right: 20px;
  bottom: 20px;
  padding: 8px 12px;
  border: 1px solid #236a63;
  background: #effff6ed;
  color: #24554e;
  font: 11px/1.5 monospace;
  letter-spacing: 0.08em;
}
html[data-signal="on"] .site-header .brand,
html[data-signal="on"] main h1 { text-shadow: -2px 0 #c125866e, 2px 0 #009ca475; }
.signal-status {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
@media (prefers-reduced-motion: no-preference) {
  html[data-signal="on"] .signal-interference::before { animation: signal-drift 900ms steps(3, end) 3; }
}
@keyframes signal-drift {
  0%, 100% { transform: translateY(0); }
  25% { transform: translateY(-12px); }
  65% { transform: translateY(9px); }
}
@media (prefers-reduced-motion: reduce) {
  .signal-interference { background: none; }
  .signal-interference::before { background: none; animation: none; }
}