.phtml

<form class="form contact"

     action="<?php /* @escapeNotVerified */ echo $block->getFormAction(); ?>"

     id="contact-form"

     method="post"

     data-hasrequired="<?php /* @escapeNotVerified */ echo __('* Required Fields') ?>"

     data-mage-init='{"validation":{}}'>

   <fieldset class="fieldset">

       <legend class="legend"><span><?php /* @escapeNotVerified */ echo __('Contact Us') ?></span></legend><br />

       <div class="field note no-label"><?php /* @escapeNotVerified */ echo __('We’ll get back to you as quickly as possible.') ?></div>

       <div class="field email required">

           <label class="label" for="email"><span><?php /* @escapeNotVerified */ echo __('Your Email') ?></span></label>

           <div class="control">

               <input name="email" id="email" title="<?php /* @escapeNotVerified */ echo __('Your Email') ?>" value="<?php echo $block->escapeHtml($this->helper('Magento\Contact\Helper\Data')->getPostValue('email') ?: $this->helper('Magento\Contact\Helper\Data')->getUserEmail()) ?>" class="input-text" type="email" data-validate="{required:true, 'validate-email':true}"/>

           </div>

       </div>

       <div class="field comment required">

           <label class="label" for="comment"><span><?php /* @escapeNotVerified */ echo __('Question') ?></span></label>

           <div class="control">

               <textarea name="comment" id="comment" title="<?php /* @escapeNotVerified */ echo __('Question') ?>" class="input-text" cols="5" rows="3" data-validate="{required:true}"><?php echo $block->escapeHtml($this->helper('Magento\Contact\Helper\Data')->getPostValue('comment')) ?></textarea>

           </div>

       </div>

       <?php echo $block->getChildHtml('form.additional.info'); ?>

   </fieldset>

   <div class="actions-toolbar">

       <div class="primary">

           <input type="hidden" name="hideit" id="hideit" value="" />

           <button type="submit" title="<?php /* @escapeNotVerified */ echo __('Submit') ?>" class="action submit primary">

               <span><?php /* @escapeNotVerified */ echo __('Submit') ?></span>

           </button>

       </div>

   </div>

</form>