body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f2f2f2;
    color: #333;
    margin: 0;
    padding: 0;
    transition: background-color 0.3s ease;
}

.container {
    max-width: 400px;
    margin: 50px auto;
    background-color: #fff;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    padding: 20px;
}

h2 {
    text-align: center;
    margin-bottom: 20px;
    color: #333;
    transition: color 0.3s ease;
}

.calculator input[type="text"] {
    width: 100%;
    padding: 10px;
    margin-bottom: 20px;
    font-size: 24px;
    border: none;
    background-color: #f2f2f2;
    text-align: right;
}

.calculator .row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 10px;
}

.calculator .key {
    flex: 1;
    padding: 10px;
    margin: 5px;
    font-size: 24px;
    text-align: center;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
    color: #333;
    background-color: #e0e0e0;
}

.calculator .key.operator {
    background-color: #ff8c00;
    color: #fff;
}

.calculator .key.equal {
    background-color: #4caf50;
    color: #fff;
}

.calculator .key.clear {
    background-color: #f44336;
    color: #fff;
}

.calculator .key:hover {
    background-color: #d5d5d5;
}

.calculator .key:active {
    background-color: #bfbfbf;
}

.calculator .key:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

.calculator .key.square-root {
    background-color: #517ef9;

}

.dark {
    background-color: #111;
    color: #fff;
}

.dark h2 {
    color: #fff;
}

.dark .calculator input[type="text"] {
    background-color: #222;
    color: #fff;
}

.dark .calculator .key.operator {
    background-color: #ff9800;
}

.dark .calculator .key.equal {
    background-color: #8bc34a;
}

.dark .calculator .key.square-root {
    background-color: #6588f9;
}