body {
    font-family: "Microsoft YaHei", "Segoe UI", sans-serif;
}
.sidebar {
    min-height: 100vh;
    background-color: #343a40;
}
.sidebar .nav-link {
    color: #adb5bd;
    padding: 0.75rem 1.25rem;
}
.sidebar .nav-link:hover,
.sidebar .nav-link.active {
    color: #fff;
    background-color: #495057;
}
.card-stat {
    text-align: center;
    padding: 1.5rem;
}
.card-stat h3 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}
.card-stat p {
    color: #6c757d;
    margin-bottom: 0;
}
.login-container {
    max-width: 400px;
    margin: 10vh auto;
}