Override form.html.twig without using theme's override file

My task is pretty simple. I just need to change “buttons” class in “inner_markup_buttons_start” block in form.html.twig of Form plugin (2.0.5) to my own class.

  {% block inner_markup_buttons_start %}
  <div class="buttons">
  {% endblock %}

I often do this by overriding the whole form.html.twig in my theme. However, doing this method caused me many problems in the past with new releases of Form plugin when there were changes in form.html.twig.

I am not an expert in Twig. I wonder if it is possible to override only the block “inner_markup_buttons_start” in my theme? I checked Twig’s documentation and Grav’s documentation but I haven’t found any solutions yet. Thanks!

The solution is so simple.

My page’s Twig file:

{% include "forms/contact.html.twig" with { form: forms('contact-form') } %}

In forms/contact.html.twig:

{% extends 'forms/form.html.twig' %}

{% block inner_markup_buttons_start %}
<div class="my-own-class">
{% endblock %}

I need more coffee.