/* 全局样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Arial", sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f0f0f0;
}

/* 计算器容器 */
.calculator {
    width: 100%;
    max-width: 400px;
    background-color: #2d2d2d;
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    padding: 20px;
}

/* 显示区域 */
.calculator-display {
    background-color: #1a1a1a;
    color: white;
    font-size: 2.5rem;
    text-align: right;
    padding: 25px 20px;
    border-radius: 10px;
    margin-bottom: 20px;
    min-height: 80px;
    overflow-x: auto;
    white-space: nowrap;
}

/* 按钮区域 */
.calculator-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}

/* 通用按钮样式 */
.btn {
    padding: 20px;
    border: none;
    border-radius: 10px;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
}

.btn:active {
    transform: translateY(0);
}

/* 数字按钮 */
.number {
    background-color: #4d4d4d;
    color: white;
}

/* 零按钮 */
.zero {
    grid-column: span 2;
}

/* AC按钮 */
.ac {
    background-color: #ff5722;
    color: white;
}

/* 删除按钮 */
.del {
    background-color: #ff9800;
    color: white;
}

/* 运算符按钮 */
.operator {
    background-color: #2196f3;
    color: white;
}

/* 等号按钮 */
.equal {
    background-color: #4caf50;
    color: white;
}

/* 响应式适配 */
@media (max-width: 400px) {
    .calculator {
        padding: 15px;
    }
    
    .calculator-display {
        font-size: 2rem;
        padding: 20px 15px;
    }
    
    .btn {
        padding: 15px;
        font-size: 1rem;
    }
}