.calculator {
    width: 100%;
    height: 100%;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.display {
    width: 100%;
    padding: 15px;
    font-size: 24px;
    text-align: right;
    background: #f8f9fa;
    border: 1px solid #dee2e6;
    border-radius: 4px;
}

.keypad {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 10px;
}

.btn {
    padding: 15px;
    font-size: 18px;
    border: 1px solid #dee2e6;
    border-radius: 4px;
    background: white;
    cursor: pointer;
    transition: all 0.2s;
}

.btn:hover {
    background: #e9ecef;
}

.btn.operator {
    background: #e7f5ff;
    color: #1971c2;
}

.btn.function {
    background: #fff9db;
    color: #e67700;
}

.btn.equal {
    background: #1971c2;
    color: white;
}

.btn.equal:hover {
    background: #1864ab;
}

.history {
    margin-top: 20px;
    padding: 15px;
    background: #f8f9fa;
    border-radius: 4px;
}

.history h3 {
    margin-bottom: 10px;
    color: #495057;
    font-size: 18px;
}

.history-item {
    padding: 10px;
    margin: 5px 0;
    background: white;
    border: 1px solid #dee2e6;
    border-radius: 4px;
    display: flex;
    justify-content: space-between;
}

.history-expression {
    color: #495057;
}

.history-result {
    color: #1971c2;
    font-weight: bold;
}