body {
    font-family: Arial, sans-serif;
    padding: 20px;
}

.container {
    max-width: 300px;
    margin: 0 auto;
}

input[type="text"],
input[type="password"],
button {
    width: 100%;
    padding: 10px;
    margin: 10px 0;
    display: block;
    box-sizing: border-box;
}

button {
    background-color: #4CAF50;
    color: white;
    border: none;
    cursor: pointer;
}

button:hover {
    background-color: #45a049;
}
/* 响应式菜单样式 */
.navbar-nav {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}
.nav-item {
    margin-bottom: 10px;
}
.nav-link {
    padding: 10px 15px;
    border-radius: 5px;
}
/* 小屏幕设备下菜单按钮样式 */
@media (max-width: 768px) {
    .navbar-nav {
        flex-direction: row;
        align-items: center;
    }
    .nav-link {
        padding: 10px;
        margin-right: 10px;
    }
}

.container h2{
    text-align: center;
}

footer {
    text-align: center;
    font-size: 12px;
    color: #999;
    margin-top: 20px;
}