body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f0f0f0;
    font-family: Arial, sans-serif;
}

.calculator {
    border: 1px solid #ccc;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.15);
    overflow: hidden;
    width: 320px;
}

#display {
    width: 100%;
    height: 70px;
    border: none;
    background-color: #222;
    color: #fff;
    text-align: right;
    padding-right: 20px;
    font-size: 2.5em;
    box-sizing: border-box;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
}

button {
    height: 70px;
    border: 1px solid #ddd;
    font-size: 1.5em;
    cursor: pointer;
    background-color: #fff;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #f9f9f9;
}

button:active {
    background-color: #e0e0e0;
}

.operator {
    background-color: #f0ad4e;
    color: white;
}

.operator:hover {
    background-color: #ec971f;
}

.equal {
    background-color: #5cb85c;
    color: white;
    grid-row: span 2; /*  يجعل الزر يساوي يأخذ صفين */
}

.equal:hover {
    background-color: #4cae4c;
}

.zero {
    grid-column: span 2; /* يجعل زر الصفر يأخذ عمودين */
}