* {
  box-sizing: border-box;
}

body {
  margin: 16px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-color: #fafafa;
  color: #212121;
  line-height: 1.5;
}

input {
  padding: 8px;
  font: inherit;
}

button {
  padding: 8px 12px;
  cursor: pointer;
}
img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 15px;
}

.gallery > li {
  list-style: none;

  transition: transform 250ms linear;
}

.gallery > li:not(:last-child) {
  margin-right: 30px;
}

.gallery > li:hover {
  transform: scale(1.12);
}

.gallery {
  display: flex;
  justify-content: center;
}

#validation-input {
  border: 3px solid #bdbdbd;
}

#validation-input.valid {
  border-color: #4caf50;
}

#validation-input.invalid {
  border-color: #f44336;
}