body {
    margin: 0;
    padding: 0;
    font-size: 1rem;
    font-family: Arial, Verdana, Helvetica, sans-serif;
    background-color: #f5f5f5;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    background-color: #ffffff;
    padding: 15px;
}

/* typo */
p {
    margin-bottom: 0;
}

h2 {
    font-size: 1.6rem;
    font-weight: normal;
    color: #023969;
}

h3 {
    margin: 0;
    color: #023969;
}

/* layout */
ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.flex {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
}

button {
    width: 100%;
    font-size: 4rem;
    font-weight: bold;
    color: #023969;
    background-color: #f5f5f5;
    border: 1px solid #023969;
    cursor: pointer;
}

button#clear {
    font-size: 1.5rem;
    font-weight: bold;
    color: #dc5c6b;
    padding: 20px 0;
    margin: 25px 0;
    border: 1px solid #dc5c6b;
    background-color: #f0f0f0;
}

/* header */
header {
    position: sticky;
    top: 0;
}

#main-head {
    background-color: #ffffff;
    padding-bottom: 5px;
}

#logo {
    margin-top: 15px;
    display: block;
}

#logo img {
    max-height: 100px;
}

#total-amount {
    font-size: 1.1rem;
}

#amount,
#change
{
    font-weight: bold;
}

#amount-money {
    border-top: 1px solid #e1e1e1;
    border-bottom: 1px solid #e1e1e1;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-top: 10px;
    padding: 10px 0;
}

#amount-money p {
    margin: 0;
    
}

input#received-amount {
    width: 100px;
    font-size: 1.1rem;
    font-weight: bold;
    text-align: right;
}

/* content */
.product-content {
    margin-bottom: 10px;
}

.product {
    flex: 1 1 60%;
    text-align: center;
    align-content: center;
    background-color: #f5f5f5;
}

p span {
    font-weight: bold;
}

.sign-minus,
.sign-plus {
    flex: 1 1 20%;
    text-align: center;
    align-content: center;
}

/* footer */
footer {
    margin-bottom: 20px;
}