Introduction

This old iOS Safari bug usually appears when a textarea inside a Bootstrap modal gets focus, but the caret or text rendering looks visually offset from the actual input box. The root problem is usually not the textarea itself. It is the combination of iOS Safari input behavior with modal positioning, transformed ancestors, and scrolling hacks.

Why the Caret Appears in the Wrong Place

On affected iOS Safari versions, especially around iOS 11, text inputs inside overlays could render incorrectly when any of these were involved:

• a parent with transform
• nested fixed-position elements
• scroll-lock tricks on body
• modal animations that move the dialog with transforms

Bootstrap modals often use transitions and overlay positioning that trigger exactly those conditions. Once the keyboard opens and Safari adjusts the viewport, the visual caret and the actual text field can become misaligned.

So even though it looks like a text-area bug, it is usually a layout and rendering interaction bug.

First Thing to Check: Transformed Ancestors

One of the most common causes is an ancestor element with transform, translate3d, or a transform-based animation.

For example, this kind of pattern can be problematic on old iOS Safari:

.modal.show .modal-dialog {
  transform: translate(0, 20px);
}

A practical workaround is to remove transform-based positioning for the modal dialog on the affected platform.

1@supports (-webkit-overflow-scrolling: touch) {
2  .modal.show .modal-dialog {
3    transform: none !important;
4  }
5}

That can reduce visual glitches because the input is no longer being rendered inside a transformed container while Safari is trying to manage focus and the on-screen keyboard.

Keep the Layout Simpler Inside the Modal

A simpler modal layout is often more stable on old Safari versions.

1<div class="modal fade" id="feedbackModal" tabindex="-1">
2  <div class="modal-dialog">
3    <div class="modal-content">
4      <div class="modal-body">
5        <textarea class="form-control" rows="5"></textarea>
6      </div>
7    </div>
8  </div>
9</div>

Try to avoid:

• deeply nested scroll containers
• custom transforms around the input
• CSS tricks that reposition the textarea

If the bug disappears when the modal content is simplified, the issue is almost certainly layout-related rather than input-related.

Watch for Body Scroll Lock Side Effects

Many modal implementations lock scrolling by modifying body styles. On iOS Safari, this can interact poorly with the virtual keyboard.

Common patterns that may cause problems:

• 'position: fixed on body'
• custom scroll wrappers
• forced height calculations based on viewport size

If your app adds custom modal behavior on top of Bootstrap, test whether disabling the extra scroll-lock layer fixes the cursor problem.

In some cases, the best workaround is to rely on Bootstrap’s normal modal behavior and remove custom body-scroll code for iOS.

A Practical JavaScript Workaround

Sometimes forcing a layout refresh after the modal becomes visible helps:

1$('#feedbackModal').on('shown.bs.modal', function () {
2  const textarea = $(this).find('textarea').get(0);
3  if (!textarea) return;
4
5  textarea.blur();
6  setTimeout(() => {
7    textarea.focus();
8  }, 50);
9});

This is not elegant, but on old iOS Safari it can nudge the browser into recalculating the focused input position after the modal settles.

Use this only as a workaround, not as the first fix. The layout issue should still be investigated.

Reduce Animation Complexity

Bootstrap modal animations are visually nice, but old mobile Safari was often more reliable when those transforms were reduced or disabled.

1@supports (-webkit-overflow-scrolling: touch) {
2  .modal.fade .modal-dialog {
3    transition: none;
4  }
5}

If removing the animation fixes the caret placement, you have confirmed that the bug is related to modal transition rendering rather than text input logic.

Long-Term Advice

If the application still needs to support old iOS Safari versions, keep modal form UIs conservative:

• fewer transform effects
• minimal nested scrolling
• straightforward positioning
• limited custom keyboard hacks

For modern platforms, many of these issues are far less common. But when debugging historical iOS web bugs, layout simplification usually wins over clever CSS.

Common Pitfalls

The most common pitfall is focusing on the textarea styles while ignoring transformed parent elements and modal animations.

Another mistake is layering custom body-scroll hacks on top of Bootstrap’s modal behavior, which increases the chance of iOS viewport glitches.

A third issue is trying JavaScript focus hacks first without checking the modal layout. Those hacks may hide the symptom without fixing the real cause.

Finally, developers often test only in desktop Safari or Chrome emulation. Old iOS Safari rendering bugs need real-device testing to be diagnosed properly.

Summary

• The cursor misalignment bug in old iOS Safari modal textareas is usually caused by layout and focus interactions, not by the textarea alone.
• Transformed ancestors and modal animations are common triggers.
• Simplifying modal structure and removing transform-based dialog movement often fixes the issue.
• Body scroll-lock logic can also interfere with iOS keyboard behavior.
• Use focus-refresh JavaScript only as a workaround after checking the CSS and layout causes first.