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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: #f0f2f5;
    color: #333;
}

/* ===== 登录页 ===== */
.login-page {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 50%, #1e3c72 100%);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
}
@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}
.login-container {
    width: 100%;
    max-width: 420px;
    padding: 20px;
}
.login-card {
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius: 24px;
    padding: 50px 35px;
    box-shadow: 0 25px 50px rgba(0,0,0,0.25);
    border: 1px solid rgba(255,255,255,0.2);
    text-align: center;
    color: white;
}
.login-header .system-badge {
    font-size: 54px;
    margin-bottom: 10px;
}
.login-header h1 {
    font-size: 22px;
    font-weight: 500;
    letter-spacing: 3px;
    margin-bottom: 5px;
}
.login-header h2 {
    font-size: 18px;
    font-weight: 300;
    margin-bottom: 30px;
    opacity: 0.9;
}
.input-group {
    position: relative;
    margin-bottom: 20px;
}
.input-icon {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 18px;
    opacity: 0.8;
}
.input-group input {
    width: 100%;
    padding: 14px 20px 14px 48px;
    border: 1px solid rgba(255,255,255,0.4);
    border-radius: 50px;
    background: rgba(255,255,255,0.2);
    color: white;
    font-size: 15px;
    outline: none;
    transition: all 0.3s;
}
.input-group input::placeholder {
    color: rgba(255,255,255,0.7);
}
.input-group input:focus {
    border-color: white;
    background: rgba(255,255,255,0.3);
    box-shadow: 0 0 15px rgba(255,255,255,0.2);
}
.btn-login {
    width: 100%;
    padding: 14px;
    border: none;
    border-radius: 50px;
    background: white;
    color: #1e3c72;
    font-size: 17px;
    font-weight: 600;
    letter-spacing: 2px;
    cursor: pointer;
    transition: all 0.3s;
    margin-top: 10px;
}
.btn-login:hover {
    background: #e8ecf1;
    box-shadow: 0 8px 20px rgba(0,0,0,0.2);
    transform: translateY(-1px);
}
.error-msg {
    background: rgba(255,80,80,0.2);
    border: 1px solid rgba(255,80,80,0.5);
    color: #ffe0e0;
    padding: 10px;
    border-radius: 50px;
    margin-bottom: 20px;
    font-size: 14px;
}

/* ===== 后台框架 ===== */
.dashboard {
    background: #f4f6f9;
}
.app-layout {
    display: flex;
    min-height: 100vh;
}
.sidebar {
    width: 230px;
    background: #0f1a2f;
    color: #b0bec5;
    display: flex;
    flex-direction: column;
    box-shadow: 4px 0 20px rgba(0,0,0,0.15);
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    z-index: 100;
}
.sidebar-brand {
    padding: 30px 20px 25px;
    text-align: center;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}
.brand-icon {
    font-size: 36px;
    margin-bottom: 8px;
}
.brand-text {
    font-size: 15px;
    letter-spacing: 2px;
    color: #ffffff;
    font-weight: 500;
}
.sidebar-nav {
    flex: 1;
    padding: 15px 0;
}
.nav-item {
    display: flex;
    align-items: center;
    padding: 13px 25px;
    color: #90a4ae;
    text-decoration: none;
    font-size: 15px;
    transition: all 0.25s;
    border-left: 3px solid transparent;
    margin: 2px 0;
}
.nav-item:hover {
    background: rgba(255,255,255,0.05);
    color: #ffffff;
    border-left-color: #4fc3f7;
}
.nav-item.active {
    background: rgba(79,195,247,0.12);
    color: #4fc3f7;
    border-left-color: #4fc3f7;
    font-weight: 500;
}
.nav-icon {
    margin-right: 12px;
    font-size: 18px;
    width: 24px;
    text-align: center;
}
.sidebar-footer {
    border-top: 1px solid rgba(255,255,255,0.08);
    padding: 10px 0;
}
.logout-btn {
    color: #ef9a9a;
}
.logout-btn:hover {
    color: #ffffff;
    background: rgba(239,83,80,0.2);
    border-left-color: #ef5350;
}
.main-area {
    margin-left: 230px;
    flex: 1;
    padding: 30px;
    min-height: 100vh;
}

/* ===== 欢迎页 ===== */
.welcome-card {
    background: white;
    border-radius: 20px;
    padding: 60px 40px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    max-width: 600px;
    margin: 40px auto;
}
.welcome-icon {
    font-size: 70px;
    margin-bottom: 20px;
}
.welcome-card h1 {
    font-size: 28px;
    color: #1e3c72;
    font-weight: 600;
    margin-bottom: 8px;
}
.welcome-sub {
    font-size: 17px;
    color: #555;
    margin-bottom: 25px;
}
.decor-line {
    width: 60px;
    height: 3px;
    background: #2a5298;
    margin: 20px auto;
    border-radius: 3px;
}
.welcome-user {
    margin-top: 15px;
    color: #777;
    font-size: 15px;
}

/* ===== 占位页 ===== */
.page-placeholder {
    background: white;
    border-radius: 20px;
    padding: 80px 40px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    max-width: 500px;
    margin: 40px auto;
}
.placeholder-icon {
    font-size: 60px;
    margin-bottom: 20px;
    opacity: 0.8;
}
.page-placeholder h2 {
    color: #1e3c72;
    margin-bottom: 10px;
}
.page-placeholder p {
    color: #999;
}

/* ===== 修改密码卡片 ===== */
.content-card {
    background: white;
    border-radius: 20px;
    padding: 35px 40px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    max-width: 550px;
    margin: 0 auto;
}
.card-title {
    font-size: 20px;
    color: #1e3c72;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 2px solid #eef1f5;
}
.form-group {
    margin-bottom: 20px;
}
.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #444;
}
.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid #dce3e8;
    border-radius: 10px;
    font-size: 15px;
    transition: 0.2s;
    background: #fafbfc;
}
.form-group input:focus {
    border-color: #2a5298;
    box-shadow: 0 0 0 3px rgba(42,82,152,0.1);
    outline: none;
    background: white;
}
.btn-submit {
    background: #1e3c72;
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    transition: 0.2s;
    margin-top: 10px;
}
.btn-submit:hover {
    background: #2a5298;
    box-shadow: 0 5px 15px rgba(30,60,114,0.3);
}
.form-msg {
    padding: 12px 18px;
    border-radius: 10px;
    margin-bottom: 20px;
    font-size: 14px;
}
.msg-success {
    background: #e8f5e9;
    color: #2e7d32;
    border: 1px solid #a5d6a7;
}
.msg-error {
    background: #ffebee;
    color: #c62828;
    border: 1px solid #ef9a9a;
}

/* ===== 响应式适配 ===== */
@media (max-width: 768px) {
    .sidebar {
        width: 200px;
    }
    .main-area {
        margin-left: 200px;
        padding: 20px;
    }
}