index.css

body {
    background-image: url("https://miro.medium.com/max/750/1*KbaWpqfp7OYlShdsiN24fA.png");
    background-size: cover;
    background-repeat: no-repeat;
    font-family: 'Gemunu Libre', sans-serif;
    font-weight: bold;
    text-align: center;
    color: #FB4B4E;
    text-shadow: 0px 0px 5px gray;
}

#size {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    
}

h1 {
    margin-top: 10px;
    margin-bottom: 10px;
}

h2 {
    font-size: 50px;
    margin-top: 0;
    margin-bottom: 20px;
}

button {
    border: none;
    padding-top: 10px;
    padding-bottom: 10px;
    color: white;
    font-weight: bold;
    width: 200px;
    margin-bottom: 5px;
    border-radius: 5px;
}

#increment-btn {
    background: darkred;
}

#save-btn {
    background: darkgreen;
}