<div class="columns mx-1">
  <div class="column is-half is-offset-one-quarter">

    <section class="hero is-primary mb-4">
      <div class="hero-body">
        <p class="title">
          SuperHero FAQ
        </p>
        <p class="subtitle">
    Frequently Asked Question about Superhero
        </p>
      </div>
    </section>
  
    
    <section>
<div>
      <label for="searchbox" class="is-size-5">Search</label>
      <input class='input mb-5' type="search" 
            id="searchbox" placeholder="Live search keyword..">
 </div>

<div class="box">
 <strong>What is Kryptonite?</strong>
  <p> It's Superman's weakness</p>
</div>

<div class="box">
  <strong> How did Spider-man get superpowers?</strong>
  <p>  Spider-man was bitten by a radioactive spider on a lab. </p>
  
    
  <!-- Put any keywords here -->
  <span class="is-hidden">secret</span> 
</div>

<div class="box">
  <strong>Who were Batman's parents?</strong>
  <p> Thomas Wayne and Martha Wayne. </p>
</div>

<div class="box">
  <strong>Who is Malekith?</strong>
  <p>The villain of ‘Thor: The Dark World </p>
</div>
    
<div class="box">
  <strong>What's Wonder Woman's weapon?</strong>
  <p>A magic lasso and bullet-proof bracelets </p>
</div>
    
<div class="box">
  <strong>What's Strom super power?</strong>
  <p>She can manipulate and resist the weather</p>
</div>
    
<div class="box">
  <strong>What's Strom super power?</strong>
  <p>She can manipulate and resist the weather</p>
</div>
    
<div class="box">
  <strong>What is Eye of Agamotto?</strong>
  <p>It's a place where the Time Stone is hidden in Doctor Strange </p>
</div>
    
<div class="box">
  <strong>What is Paradise Island?</strong>
  <p>It's where Wonder Woman comes from. </p>
</div>
    
<div class="box">
  <strong>Who was the sidekick of Aquaman?</strong>
  <p>The sidekick of Aquaman, is someone called Aqualad. </p>
</div>
      
    </section>

  </div>
</div>
let cards = document.querySelectorAll('.box')
    
function liveSearch() {
    let search_query = document.getElementById("searchbox").value;
    
    //Use innerText if all contents are visible
    //Use textContent for including hidden elements
    for (var i = 0; i < cards.length; i++) {
        if(cards[i].textContent.toLowerCase()
                .includes(search_query.toLowerCase())) {
            cards[i].classList.remove("is-hidden");
        } else {
            cards[i].classList.add("is-hidden");
        }
    }
}

//A little delay
let typingTimer;               
let typeInterval = 500;  
let searchInput = document.getElementById('searchbox');

searchInput.addEventListener('keyup', () => {
    clearTimeout(typingTimer);
    typingTimer = setTimeout(liveSearch, typeInterval);
});

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/bulma/0.9.3/css/bulma.min.css

External JavaScript

This Pen doesn't use any external JavaScript resources.