* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

.sert {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: rgb(199, 199, 199);
    padding: 100px 0px;
}

.sert img {
    width: 28%;
    margin: 2%;
}
@media (max-width:700px) {
  .sert {
 flex-direction: column;
 height: 100%;
  padding: 50px 0px;
}
.sert img {
    width: 80%;
    margin: 2%;
}
}