body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    overflow-x: hidden; /* 防止水平滚动 */
    background: linear-gradient(to bottom, #1e3c72, #2a5298); /* 渐变背景 */
}
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 20px;
    background-color: transparent;
    box-shadow: none; /* 初始状态无阴影 */
    position: fixed;
    width: 100%;
    top: 0;
    transition: background-color 0.3s, box-shadow 0.3s; /* 添加阴影的过渡效果 */
    z-index: 1000; /* 确保 header 在最上层 */
}
.logo {
    font-size: 24px;
    font-weight: bold;
    background: linear-gradient(90deg, red, red, orange, yellow, green, blue, indigo, violet, black, red); /* 增加开始的红色时长 */
    -webkit-background-clip: text;
    color: transparent;
    animation: gradient 3s infinite linear; /* 将动画速度加快到3秒 */
    background-size: 1000% 1000%; /* 增加背景尺寸以提高连贯性 */
}
@keyframes gradient {
    0% { background-position: 0% 50%; }
    100% { background-position: 100% 50%; }
}
nav {
    display: flex;
    gap: 20px;
}
nav a {
    text-decoration: none;
    color: white; /* 初始状态为白色文字 */
    font-weight: bold;
    transition: color 0.3s; /* 添加颜色过渡效果 */
}
nav a.active {
    color: lightblue; /* 初始状态为浅蓝色文字 */
}
.login-btn {
    background-color: #007bff;
    color: #fff;
    padding: 5px 10px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin-left: 20px; /* 添加左边距 */
}
.content {
    display: flex;
    justify-content: center;
    align-items: center;
    height: calc(100vh - 60px);
    text-align: center;
    margin-top: 60px;
}
.content .text-container {
    text-align: left; /* 调整为左对齐 */
}
.content .logo {
    font-size: 48px;
    background: linear-gradient(90deg, red, orange, yellow, green, blue, indigo, violet, black, red, red); /* 增加开始的红色时长 */
    -webkit-background-clip: text;
    color: transparent;
    animation: gradient 3s infinite linear; /* 将动画速度加快到3秒 */
    background-size: 1000% 1000%; /* 增加背景尺寸以提高连贯性 */
}
.content .more-btn {
    display: flex;
    justify-content: center; /* 水平居中 */
    align-items: center; /* 垂直居中 */
    margin-top: 20px;
    font-size: 18px;
    cursor: pointer;
    border: 2px solid #007bff; /* 添加边框 */
    border-radius: 30px; /* 更加圆滑的边框 */
    padding: 10px 20px; /* 添加内边距 */
    color: #fff; /* 将按钮文字颜色改为白色 */
}
.content .image-container {
    margin-left: 20px; /* 添加左边距 */
}
.content .image-container img {
    max-width: 100%;
    height: auto;
    border-radius: 10px; /* 添加圆角 */
}
.footer {
    text-align: center;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 -2px 4px rgba(0, 0, 0, 0.1);
}
.footer a {
    text-decoration: none;
    color: #007bff;
}
.success-message {
    display: none;
    color: green;
    font-weight: bold;
    text-align: center;
    margin-top: 10px;
}
.background-element {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    animation: float 6s ease-in-out infinite;
}
@keyframes float {
    0% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
    100% { transform: translateY(0); }
}
/* 电脑屏幕背景设计 */
@media (min-width: 768px) {
    .background-element.large {
        width: 300px;
        height: 300px;
        top: 20%;
        left: 10%;
    }
    .background-element.medium {
        width: 200px;
        height: 200px;
        top: 50%;
        left: 70%;
    }
    .background-element.small {
        width: 100px;
        height: 100px;
        top: 80%;
        left: 30%;
    }
}
/* 手机屏幕背景设计 */
@media (max-width: 767px) {
    .background-element.large {
        width: 150px;
        height: 150px;
        top: 10%;
        left: 5%;
    }
    .background-element.medium {
        width: 100px;
        height: 100px;
        top: 40%;
        left: 60%;
    }
    .background-element.small {
        width: 50px;
        height: 50px;
        top: 70%;
        left: 20%;
    }
}
#login-modal, #forgot-password-modal {
    border-radius: 15px; /* 圆角效果 */
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2); /* 阴影效果 */
    background: linear-gradient(to bottom, #ffffff, #f0f0f0); /* 渐变背景 */
}
#login-modal input, #forgot-password-modal input {
    border-radius: 5px; /* 输入框圆角效果 */
    box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1); /* 内阴影效果 */
}
#login-modal .login-btn, #forgot-password-modal .send-reset-email-btn {
    border-radius: 5px; /* 按钮圆角效果 */
    background: linear-gradient(to right, #007bff, #0056b3); /* 按钮渐变背景 */
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2); /* 按钮阴影效果 */
}
.introduction {
    text-align: center;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2); /* 阴影效果 */
    border-radius: 15px; /* 圆角效果 */
    background: linear-gradient(to bottom, #ffffff, #f0f0f0); /* 渐变背景 */
    margin-top: 20px;
}
.user-count {
    text-align: center;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2); /* 阴影效果 */
    border-radius: 15px; /* 圆角效果 */
    background: linear-gradient(to bottom, #ffffff, #f0f0f0); /* 渐变背景 */
    margin-top: 20px;
}