自動拡張テキストエリア

<%# Textarea autosize demo: type and the field grows to fit, up to maxRows (then it
    scrolls). The controller sets the element's inline height from scrollHeight and
    toggles data-at-max-rows at the cap; it listens for input itself, so no consumer
    JS is needed. This demo only sets the textarea's base look. %>
<div class="textarea-autosize-demo">
  <label class="textarea-autosize-demo__label" for="ta-autosize">
    <%= t("components.textarea_autosize.demo.label") %>
  </label>
  <textarea
    id="ta-autosize"
    class="textarea-autosize-demo__field"
    rows="2"
    placeholder="<%= t('components.textarea_autosize.demo.placeholder') %>"
    data-controller="stimeo--textarea-autosize"
    data-stimeo--textarea-autosize-max-rows-value="8"></textarea>
</div>

/*
 * Presentation-only styles for the textarea autosize demo.
 * The library owns the textarea's height (set inline from scrollHeight) and toggles
 * data-at-max-rows; this CSS only provides the base look and the line metrics the
 * controller measures against. resize:none because the library manages height.
 */

.textarea-autosize-demo {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  max-width: 32rem;
}

.textarea-autosize-demo__label {
  font-weight: 600;
  color: var(--fg);
}

.textarea-autosize-demo__field {
  width: 100%;
  padding: 0.5rem;
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  font: inherit;
  line-height: 1.5;
  resize: none;
  overflow: hidden;
}