:root {
    --sidebar-width: 240px;
    --sidebar-bg-color: var(--bg-color); /* Light background */
    --sidebar-border-color: var(--border-color);
    --sidebar-link-color: var(--text-color);
    --sidebar-link-hover-bg: var(--hover-bg-color);
    --sidebar-link-active-color: #007bff; /* <-- 파란색으로 변경 */
    --sidebar-link-active-bg: #e9ecef; /* Slightly different active background */
}

.sidebar {
    width: var(--sidebar-width);
    background-color: var(--sidebar-bg-color);
    border-right: 1px solid var(--sidebar-border-color);
    padding: calc(var(--spacing-unit) * 2) 0;
    flex-shrink: 0; /* Prevent sidebar from shrinking */
}

.sidebar nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: block;
}

.sidebar nav ul li a {
    display: block;
    padding: calc(var(--spacing-unit) * 1.2) calc(var(--spacing-unit) * 2);
    color: var(--sidebar-link-color);
    text-decoration: none;
    font-size: 0.95em;
    border-left: 3px solid transparent; /* For active indicator */
    transition: background-color 0.2s ease, border-left-color 0.2s ease, color 0.2s ease;
}

.sidebar nav ul li a:hover {
    background-color: var(--sidebar-link-hover-bg);
    color: var(--sidebar-link-active-color);
}

.sidebar nav ul li.active > a {
    background-color: var(--sidebar-link-active-bg);
    color: var(--sidebar-link-active-color);
    font-weight: 600;
    border-left-color: var(--sidebar-link-active-color);
}

/* Responsive adjustments for sidebar layout */
.main-content.has-sidebar .container.sidebar-container {
    display: flex;
    gap: calc(var(--spacing-unit) * 3); /* Gap between sidebar and main content */
}

.main-content.has-sidebar .main-column {
    flex-grow: 1; /* Allow main content to take remaining space */
    min-width: 0; /* Prevent content overflow issues in flex items */
}

/* Hide sidebar on smaller screens (adjust breakpoint as needed) */
@media (max-width: 768px) { 
    .sidebar {
        display: none; /* Hide sidebar */
    }

    .main-content.has-sidebar .container.sidebar-container {
        display: block; /* Stack content vertically */
        gap: 0;
        padding: 5px;
    }
    /* Adjust padding/margins if needed when sidebar is hidden */
} 

.sidebar .sidebar-title {
    padding: calc(var(--spacing-unit) * 1.2) calc(var(--spacing-unit) * 2);
    margin-bottom: calc(var(--spacing-unit) * 1.5);
    font-size: 1.1em;
    font-weight: 600;
    color: var(--primary-color);
    border-bottom: 1px solid var(--sidebar-border-color);
    /* Ensure no floats or unexpected display properties */
    display: block;
    float: none;
}