CSS parallax effect. How to change the top margin

Question

I'm trying to deal with this example of parallax effect on CSS. How can I change / remove the space between the first image and the top edge of the page? I am "playing" with the code for a long time but have not yet figured it out.

/* ============================================================
  PRIMARY STRUCTURE
============================================================ */
.container {
  max-width: 960px;
  margin: 0 auto;
}
/* ============================================================
  SECTIONS
============================================================ */
section.module:last-child {
  margin-bottom: 0;
}
section.module h2 {
  margin-bottom: 40px;
  font-family: "Roboto Slab", serif;
  font-size: 30px;
}
section.module p {
  margin-bottom: 40px;
  font-size: 16px;
  font-weight: 300;
}
section.module p:last-child {
  margin-bottom: 0;
}
section.module.content {
  padding: 40px 0;
}
section.module.parallax {
  height: 600px;
  background-position: 50% 50%;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;
}
section.module.parallax h1 {
  color: rgba(255, 255, 255, 0.8);
  font-size: 48px;
  line-height: 600px;
  font-weight: 700;
  text-align: center;
  text-transform: uppercase;
  text-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
}
section.module.parallax-1 {
  background-image: url("http://www.fonstola.ru/pic/201112/2560x1600/fonstola.ru-63832.jpg");
}
section.module.parallax-2 {
  background-image: url("http://hdoboi.net/uploads/hd/95263_krasivyiy_osenniy_peyzaj.jpg");
}
section.module.parallax-3 {
  background-image: url("http://drobs.ru/opyat/8/peyzazh_priroda_holmy_derevya_zelen_tuman_rassvet_solnce_5576x3087.jpg");
}

@media all and (min-width: 600px) {
  section.module h2 {
    font-size: 42px;
  }
  section.module p {
    font-size: 20px;
  }
  section.module.parallax h1 {
    font-size: 96px;
  }
}
@media all and (min-width: 960px) {
  section.module.parallax h1 {
    font-size: 160px;
  }
}

<section class="module parallax parallax-1">
  <div class="container">
    <h1>Serene</h1>
  </div>
</section>

<section class="module content">
  <div class="container">
    <h2>Lorem Ipsum Dolor</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
  </div>
</section>

<section class="module parallax parallax-2">
  <div class="container">
    <h1>Rise</h1>
  </div>
</section>

<section class="module content">
  <div class="container">
    <h2>Lorem Ipsum Dolor</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
  </div>
</section>

<section class="module parallax parallax-3">
  <div class="container">
    <h1>Calm</h1>
  </div>
</section>

<section class="module content">
  <div class="container">
    <h2>Lorem Ipsum Dolor</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
  </div>
</section>

Answer 1

The problem described above is caused by margins collapsing. Refer to: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Box_Model/Mastering_margin_collapsing

You can solve it by removing the default top margin of the first h1 elementand the default body margin. Refer to the code below:

/* ============================================================
  PRIMARY STRUCTURE
============================================================ */
.container {
  max-width: 960px;
  margin: 0 auto;
}
/* ============================================================
  SECTIONS
============================================================ */
section.module:last-child {
  margin-bottom: 0;
}
section.module h2 {
  margin-bottom: 40px;
  font-family: "Roboto Slab", serif;
  font-size: 30px;
}
section.module p {
  margin-bottom: 40px;
  font-size: 16px;
  font-weight: 300;
}
section.module p:last-child {
  margin-bottom: 0;
}
section.module.content {
  padding: 40px 0;
}
section.module.parallax {
  height: 600px;
  background-position: 50% 50%;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;
}
section.module.parallax h1 {
  color: rgba(255, 255, 255, 0.8);
  font-size: 48px;
  line-height: 600px;
  font-weight: 700;
  text-align: center;
  text-transform: uppercase;
  text-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
}
section.module.parallax-1 {
  background-image: url("http://www.fonstola.ru/pic/201112/2560x1600/fonstola.ru-63832.jpg");
}
section.module.parallax-2 {
  background-image: url("http://hdoboi.net/uploads/hd/95263_krasivyiy_osenniy_peyzaj.jpg");
}
section.module.parallax-3 {
  background-image: url("http://drobs.ru/opyat/8/peyzazh_priroda_holmy_derevya_zelen_tuman_rassvet_solnce_5576x3087.jpg");
}

/* Added to remove the margin at the top of the page and the default body margin */
.no-margin-top {
   margin-top: 0;
}

body {
    margin: 0;
}

@media all and (min-width: 600px) {
  section.module h2 {
    font-size: 42px;
  }
  section.module p {
    font-size: 20px;
  }
  section.module.parallax h1 {
    font-size: 96px;
  }
}
@media all and (min-width: 960px) {
  section.module.parallax h1 {
    font-size: 160px;
  }
}

<section class="module parallax parallax-1">
  <div class="container">
    <h1 class="no-margin-top">Serene</h1>
  </div>
</section>

<section class="module content">
  <div class="container">
    <h2>Lorem Ipsum Dolor</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
  </div>
</section>

<section class="module parallax parallax-2">
  <div class="container">
    <h1>Rise</h1>
  </div>
</section>

<section class="module content">
  <div class="container">
    <h2>Lorem Ipsum Dolor</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
  </div>
</section>

<section class="module parallax parallax-3">
  <div class="container">
    <h1>Calm</h1>
  </div>
</section>

<section class="module content">
  <div class="container">
    <h2>Lorem Ipsum Dolor</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
  </div>
</section>