body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: 'Arial', sans-serif;
    background-color: #f4f4f4;
}

.calculator {
    background-color: #fff;
    max-width: 300px;
    padding: 30px;
    text-align: center;
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.history {
    height: 100px;
    width: 100%;
    margin-top: 10px;
    padding: 10px;
    background-color: #e9e9e9;
    border-radius: 5px;
    overflow-y: auto;
    display: none;
    font-family: monospace;
    font-size: 12px;
}

.theme-toggle {
    margin-bottom: 10px;
    text-align: right;
}

button {
    padding: 15px;
    font-size: 20px;
    margin: 5px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.display {
    margin-bottom: 20px;
}

input {
    width: 94%;
    height: 50px;
    font-size: 24px;
    text-align: right;
    padding: 10px 3%;
    border: none;
    border-radius: 5px;
    background-color: #f4f4f4;
    box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.1);
}

button.btn {
    width: 19%;
    background-color: #e0e0e0;
}

button.operator {
    background-color: #f9a825;
    color: #fff;
}

button#equals {
    background-color: #00c853;
    color: white;
}

.dark-mode {
    background-color: #333;
    color: white;
}

.dark-mode button {
    background-color: #555;
    color: white;
}

.dark-mode button.operator {
    background-color: #ff8f00;
}

.dark-mode button#equals {
    background-color: #00e676;
}

.dark-mode input {
    background-color: #555;
    color: white;
}

.lastRow {
    padding: 0px;
}

.lastRow .cBtn {
    width: 16%;
    padding: 15px;
    font-size: 15px !important;
}

.lastRow .arrowBtn {
    width: 20%;
    padding: 15px;
    font-size: 15px !important;
}

.lastRow .clearBtn {
    width: 20%;
    padding: 15px 8px;
    font-size: 15px !important;
    display: none;
}

.lastRow .darkBtn {
    width: 20%;
    padding: 15px 8px;
    font-size: 15px !important;
}