* {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.container {
    position: relative;
    width: 50%;
}

.container img {
    width: 100%;
}

.container .btn {
    position: absolute;
    border: none;
    padding: 4px 10px;
    background-color: #0081cb;
    color: #fff;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    cursor: pointer;    
}