@import url("https://fonts.googleapis.com/css?family=Open+Sans:400,700&display=swap");

* {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}
body {
  min-height: 100vh;
  background: #180b24;
  color: #ffffff;
  font-family: "Open Sans", sans-serif;
  /* center the .app container horizontally */
  display: flex;
  justify-content: center;
}
/* display the header, form and section in a single column */
.app {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin: 3rem 1rem;
}
/* display the input and submit button side by side, with the former growing to cover the available space */
.app form {
  margin: 3.5rem 0;
  display: flex;
  align-items: center;
  position: relative;
  border-bottom: 2px solid currentColor;
}
/* absolute position the label above the form */
.app form label {
  z-index: -5;
  position: absolute;
  bottom: 100%;
  left: 0;
  font-size: 0.75rem;
  text-transform: uppercase;
  transition: opacity 0.2s ease-out;
  transition-delay: 0.15s; /* small delay as the focus is removed */
}
/* when the form has focus reduce the weight of the label */
.app form:focus-within label {
  opacity: 0.7;
  transition-delay: 0; /* no delay as the focus is gained */
}

/* when the form has focus animate the svg to rotate back to 0 */
.app form:focus-within button svg {
  transform: rotate(0);
  transition-delay: 0.15s; /* small delay as the focus is gained */
}
.app form input {
  outline: none;
  flex-grow: 1;
  font-family: inherit;
  font-size: 1.2rem;
  color: inherit;
  background: none;
  border: none;
  padding: 0.5rem 0;
}
.app form button {
  margin-left: 0.5rem;
  background: none;
  border: none;
  width: 45px;
  height: 45px;
  color: inherit;
  padding: 5px;
}
/* rotate the svg by default */
.app form button svg {
  transition: transform 0.25s ease-out;
  transform: rotate(45deg);
  width: 100%;
  height: 100%;
  display: block;
}
/* display the articles in a row */
.app section {
  display: flex;
  align-items: flex-end;
  position: relative;
}
/* animate the articles to appear one after another (delay included in the script) */
.app section article {
  color: inherit;
  text-decoration: none;
  padding: 0 0.25rem;
  animation: addBook 0.7s ease-out both;
  /* position relative to absolute position the div describing the book below the article */
  position: relative;
}
/* animation for the articles */
@keyframes addBook {
  from {
    opacity: 0;
    visibility: hidden;
  }
  to {
    opacity: 1;
    visibility: visible;
  }
}
/* when hovering the articles scale the svg element to as if picking out the book */
.app section article svg {
  transition-property: transform, opacity;
  transition-duration: 0.15s;
  transition-timing-function: ease-in-out;
  transform-origin: 50% 100%;
  opacity: 0.8;
}
.app section article:hover svg {
  transform: scale(1.1);
  opacity: 1;
}
/* position the container describing the book below the svg */
.app section article div {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translate(-50%, 5px);
  white-space: nowrap;
  background: #fff;
  color: #000;
  /* include more whitespace atop the container to make space for the clip-path */
  padding: 0.5rem 1rem;
  padding-top: 1rem;
  /* add an arrow pointing upwards by clipping the background */
  clip-path: polygon(
    0% 0.5rem,
    42% 0.5rem,
    50% 0%,
    58% 0.5rem,
    100% 0.5rem,
    100% 100%,
    0% 100%
  );
  /* by default hide the container */
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
}
/* on hover show the container describing the information */
.app section article:hover div {
  /* transition only as the hover event occurs */
  transition-property: opacity, visibility;
  transition-duration: 0.15s;
  transition-timing-function: ease-in-out;
  transition-delay: 0.1s;
  opacity: 1;
  visibility: visible;
}
.app section article div h1 {
  font-size: 1rem;
}
.app section article div h2 {
  font-size: 0.9rem;
}
.app section article div p {
  font-size: 0.9rem;
}