/* Схлопывание через max-height: текст остаётся в потоке и доступен поиску. */
.seo-block { margin: 3rem auto; }

.seo-block__body {
  position: relative;
  max-height: 12rem;
  overflow: hidden;
  transition: max-height .3s ease;
}

.seo-block__body::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 5rem;
  background: linear-gradient(to bottom, rgba(255,255,255,0), rgba(255,255,255,1));
  pointer-events: none;
}

.seo-block.is-open .seo-block__body { max-height: none; }
.seo-block.is-open .seo-block__body::after { display: none; }

.seo-block__toggle {
  margin-top: 1rem;
  background: none;
  border: 1px solid currentColor;
  border-radius: 2rem;
  padding: .6rem 1.6rem;
  cursor: pointer;
  font: inherit;
}