style.css

@import url("https://fonts.googleapis.com/css?family=Bebas+Neue&display=swap");

html {
  box-sizing: border-box;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Bebas Neue, sans-serif;
  background-color: #eaeaea;
  background-image: url("data:image/svg+xml,%3Csvg width='6' height='6' viewBox='0 0 6 6' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='%23000000' fill-opacity='0.05' fill-rule='evenodd'%3E%3Cpath d='M5 0h1L0 6V5zM6 5v1H5z'/%3E%3C/g%3E%3C/svg%3E");
}

h1 {
  text-align: center;
  margin-top: 25px;
  margin-bottom: 15px;
  font-size: 40px;
  letter-spacing: 5px;
}

/* Loader */
.loader {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.8);
}

.loader img {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

/* Image Container */
.image-container {
  margin: 10px 30%;
}

.image-container img {
  width: 100%;
  margin-top: 5px;
}

/* Back on top button */
#topBtn {
  display: none;
  position: fixed;
  bottom: 20px;
  right: 30px;
  z-index: 99;
  font-size: 1.5rem;
  border: none;
  outline: none;
  background-color: #c31010;
  color: white;
  cursor: pointer;
  padding: 15px;
  border-radius: 100%;
  text-align: center;
  transition: transform 80ms ease-in;
}

#topBtn:hover,
#topBtn:focus {
  background-color: #000;
  transform: scale(1.1);
}

/* Media Query: Large Smartphone Vertical */
@media screen and (max-width: 600px) {
  h1 {
    font-size: 20px;
  }

  .image-container {
    margin: 10px;
  }

  #topBtn {
    font-size: 2.5rem;
    padding: 20px;
    right: calc(50vw - 2.5rem);
  }

  #topBtn:hover,
  #topBtn:focus {
    background-color: #c31010;
    transform: scale(1.1);
  }
}