/* --- 1. 变量定义 --- */
:root {
    --primary-color: #3182ce;
    --primary-hover: #2b6cb0;
    --primary-rgb: 49, 130, 206; 
    --bg-color: #f7fafc;
    --text-color: #2d3748;
    --text-secondary: #4a5568;
    --card-bg: #ffffff;
    
    --border-color: #e2e8f0;
    --error-color: #e53e3e;
    --glass-blur: 2px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    transition: background-color 0.3s, color 0.3s, background-image 0.3s;
    background-attachment: fixed;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    -webkit-font-smoothing: antialiased;
}

input, button { font-family: inherit; }

/* ================= 卡片主体 ================= */
.login-card {
    background: var(--card-bg);
    padding: 40px 35px;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
    width: 380px;
    max-width: 90%;
    text-align: center;
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
}

.login-title {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-color);
    margin-bottom: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}
.login-title span { color: var(--primary-color); }

/* ================= 表单元素 ================= */
.form-input {
    width: 100%;
    padding: 12px 20px;
    border: 1px solid var(--border-color);
    border-radius: 50px;
    background-color: rgba(0,0,0,0.02);
    font-size: 1rem;
    color: var(--text-color);
    margin-bottom: 15px;
    outline: none;
    transition: all 0.2s;
    text-align: left; 
}

.form-input:focus {
    background-color: #fff;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(49, 130, 206, 0.15);
}
.form-input::placeholder { color: #a0aec0; }

.form-input.error {
    border-color: var(--error-color) !important;
    animation: shake 0.4s ease-in-out;
}

.error-message {
    color: var(--error-color);
    font-size: 14px;
    height: 0;
    opacity: 0;
    margin-bottom: 0;
    overflow: hidden;
    transition: all 0.3s ease;
    text-align: center;
}
.error-message.show { height: auto; margin-bottom: 15px; opacity: 1; }

.form-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 20px;
    gap: 8px; 
}

/* 返回按钮 (次级操作) */
.back-link {
    font-size: 14px;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 10px 24px;
    border-radius: 50px;
    background-color: rgba(0,0,0,0.04);
    font-weight: 500;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    flex-grow: 1;
}
.back-link:hover { 
    background-color: rgba(0,0,0,0.08); 
    color: var(--text-color); 
    transform: translateY(-1px);
}

/* 登录按钮 (主要操作 - 默认状态) */
.btn-submit {
    padding: 10px 32px;
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    border-radius: 50px;
    font-weight: 600;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.2s;
    display: inline-flex; 
    align-items: center;
    justify-content: center;
    flex-grow: 1.5;
}
.btn-submit:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(49, 130, 206, 0.3);
}

/* ================= 核心统一：壁纸模式 (Wallpaper Mode) ================= */

/* 1. 浅色壁纸 (White Glass) */
body.has-bg .login-card {
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: saturate(120%) blur(var(--glass-blur));
    -webkit-backdrop-filter: saturate(120%) blur(var(--glass-blur));
    border: 1px solid rgba(255, 255, 255, 0.3);
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1);
}

/* 壁纸模式强制文字白色 */
body.has-bg .login-title { color: #ffffff !important; text-shadow: none; }

/* 壁纸模式输入框透明化 */
body.has-bg .form-input {
    background-color: rgba(255, 255, 255, 0.2); /* 透明玻璃 */
    backdrop-filter: blur(5px);
    border-color: rgba(255, 255, 255, 0.3);
    color: #ffffff !important;
}
body.has-bg .form-input::placeholder { color: rgba(255, 255, 255, 0.7); }
body.has-bg .form-input:focus {
    background-color: rgba(255, 255, 255, 0.3);
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.2);
    border-color: #ffffff;
}

/* 壁纸模式：返回按钮 */
body.has-bg .back-link {
    background-color: rgba(255, 255, 255, 0.2);
    color: #ffffff;
}
body.has-bg .back-link:hover { background-color: rgba(255, 255, 255, 0.35); }

/* 🔥 核心修改：壁纸模式登录按钮去实白，改用半透明主色调 */
body.has-bg .btn-submit {
    /* 使用半透明的主色调背景 */
    background-color: rgba(var(--primary-rgb), 0.75);
    /* 增加磨砂感 */
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    color: #ffffff;
    /* 加一个微弱的边框增强层次感 */
    border: 1px solid rgba(255, 255, 255, 0.2);
}
body.has-bg .btn-submit:hover {
    /* 悬停时颜色加深，变得更实 */
    background-color: rgba(var(--primary-rgb), 0.9);
    box-shadow: 0 4px 15px rgba(var(--primary-rgb), 0.4);
    border-color: rgba(255, 255, 255, 0.3);
}

/* 2. 深色壁纸 (Dark Glass - 对齐 Admin) */
body.has-bg.dark-mode .login-card {
    background: rgba(20, 20, 20, 0.6);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
}

/* 深色壁纸输入框 */
body.has-bg.dark-mode .form-input {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.2);
    color: #ffffff !important;
}
body.has-bg.dark-mode .form-input::placeholder { color: rgba(255, 255, 255, 0.6); }
body.has-bg.dark-mode .form-input:focus {
    background-color: rgba(255, 255, 255, 0.2);
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.1);
}

/* 深色壁纸按钮 */
body.has-bg.dark-mode .back-link { background-color: rgba(255, 255, 255, 0.1); }
body.has-bg.dark-mode .back-link:hover { background-color: rgba(255, 255, 255, 0.2); }

/* ================= 深色模式适配 (Admin Dark - 无壁纸) ================= */
body.dark-mode { 
    background-color: #121212; 
    color: #e0e0e0;
}

body.dark-mode .login-card {
    background-color: #1e1e1e; 
    border-color: #333;
}
body.dark-mode .login-title { color: #e0e0e0; }

body.dark-mode .form-input {
    background-color: rgba(255,255,255,0.05);
    border-color: #333;
    color: #fff;
}
body.dark-mode .form-input:focus {
    border-color: var(--primary-color);
    background-color: rgba(255,255,255,0.1);
}

body.dark-mode .back-link {
    background-color: rgba(255, 255, 255, 0.1);
    color: #a0a0a0;
}
body.dark-mode .back-link:hover {
    background-color: rgba(255, 255, 255, 0.15);
    color: #fff;
}

/* 防止自动填充背景变色 */
input:-webkit-autofill {
    transition: background-color 5000s ease-in-out 0s;
    -webkit-text-fill-color: var(--text-color) !important;
}
body.dark-mode input:-webkit-autofill {
    -webkit-text-fill-color: #fff !important;
}

/* 震动动画 */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    50% { transform: translateX(5px); }
    75% { transform: translateX(-5px); }
}