body, html {
    height: 100%;
    margin: 0;
    overflow: hidden; /* 防止滚动条出现 */
}

.background-container {
    background-image: url('/img/login.jpg'); /* 使用Unsplash提供的随机图片作为背景 */
    background-size: cover;
    background-position: center;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    transition: filter 0.5s ease-in-out;
}

.background-container.blur {
    filter: blur(20px) brightness(0.7); /* 模糊和变暗效果 */
}

.main-container {
    height: 100vh;
    color: white;
}

.login-box {
    background-color: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(25px); /* 毛玻璃效果 */
    -webkit-backdrop-filter: blur(25px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    width: 350px;
    position: relative;
}

/* 用户选择头像样式 */
.user-avatar {
    position: relative;
    display: inline-block;
    margin: 0 15px;
    text-align: center;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.user-avatar:hover {
    transform: scale(1.1);
}

.user-avatar img, .user-avatar .other-user-icon {
    width: 90px;
    height: 90px;
    border-radius: 50%;
    border: 2px solid rgba(255, 255, 255, 0.5);
    object-fit: cover;
}

.user-avatar .other-user-icon {
    font-size: 3rem;
    line-height: 86px; /* 垂直居中图标 */
    background-color: rgba(0, 0, 0, 0.3);
}

.user-avatar p {
    margin-top: 10px;
    font-weight: 500;
}

.delete-icon {
    position: absolute;
    top: -5px;
    right: -5px;
    background-color: rgba(0, 0, 0, 0.7);
    color: white;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    display: none; /* 默认隐藏 */
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

.user-avatar:hover .delete-icon {
    display: flex;
}

/* 登录框摇晃动画 */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-10px); }
    20%, 40%, 60%, 80% { transform: translateX(10px); }
}

.shake-animation {
    animation: shake 0.5s;
}

.back-button {
    position: absolute;
    top: 20px;
    left: 20px;
}