html, body {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Helvetica, Arial, sans-serif;
}
@keyframes pulse {
  from{
  transform: scale(1);
}
  to{
    transform: scale(1.1);
  }
}
.header__wrapper {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 70px;
  margin: auto;
}

.menu__item {
  margin-right: 10px;
  color: black;
  text-decoration: none;
}

.menu__item:last-of-type {
  margin-right: 0;
}

.cards {
  background-color: #000;
  color: #fff;
}

.cards__wrapper {
  width: 490px;
  margin: auto;
  padding: 50px 0;
}

.title {
  margin: 0;
  line-height: 56px;
  font-size: 54px;
}

.subtitle {
  line-height: 19px;
  font-size: 14px;
  margin-top: 35px;
  margin-bottom: 55px;
  max-width: 350px;
}

.demo {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

.demo__item {
  overflow: hidden;
  background-color: #202020;
  width: 240px;
  height: 240px;
  margin-right: 10px;
  margin-top: 10px;
  position: relative;
  border-radius: 4px;
  background-size: cover;
}

.demo__item:nth-of-type(2n) {
  margin-right: 0;
}

.demo__item:first-of-type, .demo__item:nth-of-type(2) {
  margin-top: 0;
}

.demo__item-title {
  width: 158px;
  position: absolute;
  bottom: 15px;
  left: 15px;
  margin: 0;
  line-height: 30px;
  font-size: 30px;
  font-weight: normal;
}

.demo__item-subtitle {
  font-size: 14px;
  line-height: 21px;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-top: 24px;
  margin-left: 16px;
  width: 158px;
}

.demo__item-subtitle_kusto {

  position: absolute;
  top: 24px;
  left: 16px;
  margin: 0;
  opacity: 0;
  transition: opacity 0.3s ease;
}
.demo__item:hover .demo__item-subtitle_kusto{
  opacity: 1;
}
.demo__item:hover .demo__wrapper_kusto{
  transform: scale(1.05);
}
.demo__item_starman:hover{
  box-shadow: 0 0 20px #4E52B0;
}
.demo__wrapper {
  height: 100%;
  width: 100%;
  background-size: cover;
}

.demo__wrapper_kusto {
  transition: transform 0.9s ease-in-out;
  background-image: url(https://pictures.s3.yandex.net/animation_topic/kusto.png);
}

.demo__item_rossie {
  background-image: url(https://pictures.s3.yandex.net/animation_topic/rossie.png);
}

.demo__item_baumgartner {
  background-image: url(https://pictures.s3.yandex.net/animation_topic/baumgartner.png);
}

.demo__item_starman {
  transition: box-shadow 0.3s ease;
  background-image: url(https://pictures.s3.yandex.net/animation_topic/starman.png);
}
demo__item.demo__wrapper_kusto{
  transform: scale(1.05);
}
.demo__item-ico {
  animation: pulse 1s ease-in-out normal altternate;
  position: absolute;
  top: 24px;
  right: 16px;
  width: 40px;
}

.demo__item-subtitle_baumgartner::after {
  content: '3';
  position: absolute;
  top: 35px;
  right: 15px;
  font-size: 72px;
}