.demo-not {
  padding: 15px;
  margin: 10px 0;
  border: 2px solid #ddd;
  border-radius: 5px;
  background: #fff;
}

@media not screen and (max-width: 700px) {
  .demo-not {
    background-color: #ffeaea;
    border-color: #dc3545;
  }
  .demo-not::before {
    content: "✓ NOT condition met: Screen width is NOT ≤700px";
    display: block;
    color: #dc3545;
    font-weight: bold;
    margin-bottom: 10px;
  }
}