body {
    /* display: flex; */
    justify-content: center;
    overflow-x: hidden;
    align-items: center;
    /* height: 100vh; */
    background-color: #f5f5f5; /* the best background color for an SEO */
}

#input-container {
    max-width: 1800px;
    width: 100%;
    display: flex;
    margin: 0 auto;
    justify-content: space-between;
    align-items: center;
    flex-direction: row;
    gap: 10px;
    margin-top: 30px;
}

#inner-container {
    /* width: 100%; */
    border-radius: 5px;
    padding: 20px;
    max-width: 1000px;
    margin: 0 auto;
}

#main-input {
    width: 100%;
    font-size: 20px;
    padding: 10px;
    border: 1px solid #ccc;
    outline: none;
}

#calculate {
    width: 100%;
    font-size: 20px;
    padding: 10px;
    border: 1px solid #ccc;
    outline: none;
    margin-top: 10px;
    cursor: pointer;
    color: black;
    margin-top: 20px;
}

#operator {
    font-size: 20px;
    padding: 10px;
    border: 1px solid #ccc;
    outline: none;
    appearance: none;
}

#output {
    margin-top: 10px;
}

section {
    max-width: 1090px;
    margin: 0 auto;
    width: 100%;
}