body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: #f4f6f9;
    color: #333;
    margin: 0;
    display: flex;
    height: 100vh;
}

.sidebar {
    width: 250px;
    background-color: #2c3e50; /* Dark blue-gray for sidebar */
    color: #ecf0f1; /* Light gray text */
    display: flex;
    flex-direction: column;
    padding-top: 20px;
}

.sidebar-header {
    padding: 0 20px 20px 20px;
    text-align: center;
    border-bottom: 1px solid #34495e;
}

.sidebar-header h3 {
    margin: 0;
    font-size: 1.5rem;
    color: #ffffff; /* White header text */
}

.sidebar-nav {
    list-style: none;
    padding: 20px 0;
    margin: 0;
    flex-grow: 1;
}

.sidebar-nav a {
    display: block;
    color: #ecf0f1;
    text-decoration: none;
    padding: 15px 25px;
    font-size: 1.1rem;
    transition: background-color 0.3s, padding-left 0.3s;
}

.sidebar-nav a:hover,
.sidebar-nav a.active {
    background-color: #34495e; /* Slightly lighter dark blue on hover */
    padding-left: 30px;
    border-left: 3px solid #27ae60; /* Green accent */
}

.main-content {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
}

header.top-bar {
    background-color: #ffffff;
    padding: 15px 30px;
    border-bottom: 1px solid #dee2e6;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

header.top-bar h1 {
    margin: 0;
    font-size: 1.8rem;
    font-weight: 500;
}

.content {
    padding: 30px;
    flex-grow: 1;
}

.card {
    background-color: #ffffff;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.08);
    padding: 20px;
    margin-bottom: 20px;
}

.card-header {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 15px;
    border-bottom: 1px solid #eee;
    padding-bottom: 10px;
    color: #2c3e50;
}

/* Responsive */
@media (max-width: 768px) {
    body {
        flex-direction: column;
    }
    .sidebar {
        width: 100%;
        height: auto;
        flex-direction: row;
        align-items: center;
        padding-top: 0;
    }
    .sidebar-header {
        padding: 15px;
        border-bottom: none;
    }
    .sidebar-nav {
        display: flex;
        flex-direction: row;
        padding: 0;
        justify-content: center;
    }
    .sidebar-nav a {
        padding: 15px;
        border-left: none;
        border-bottom: 3px solid transparent;
    }
    .sidebar-nav a:hover,
    .sidebar-nav a.active {
        padding-left: 15px;
        border-left: none;
        border-bottom: 3px solid #27ae60;
        background-color: transparent;
    }
    header.top-bar {
        padding: 15px;
    }
    .content {
        padding: 15px;
    }
}