body {
    font-family: Tahoma, sans-serif;
    direction: rtl;
    margin: 20px;
    background-color: #fdfdfd;
}

h2 {
    text-align: center;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
}

th, td {
    border: 1px solid #ccc;
    padding: 8px;
    text-align: center;
}

th {
    background-color: #e0e0e0;
}

tr.invalid {
    background-color: khaki !important;
}

td[contenteditable="true"] {
    background-color: #fff;
    cursor: text;
}

button {
    margin-top: 15px;
    padding: 8px 12px;
    font-size: 14px;
}