/* =================================
    CSS VARIABLES (Light & Dark Mode)
    ================================= */
:root {
    /* Light Mode */
    --body-background: #f8f8f8;
    --main-text-color: #555;
    --heading-color: #2c3e50;
    --intro-heading-border: #eee;
    --card-background: #fff;
    --card-border: #e0e0e0;
    --card-shadow: 0 4px 10px rgba(0,0,0,0.08);
    --diff-card-background: #fcfdff;
    --diff-card-border: #e9f0ff;
    --diff-card-shadow: 0 1px 5px rgba(0,0,0,0.04);
    --strong-text-color: #333;
    --sidebar-border-color: #ccc;
    --sidebar-menu-border: #ccc;
    --sidebar-link-color: #555;
    --sidebar-link-hover-bg: #f0f0f0;
    --sidebar-link-hover-color: #333;
    --sidebar-active-bg: #e6f3ff;
    --sidebar-active-color: #004c87;
    --sidebar-active-border: #0066cc;
    --filter-header-bg: #f7f7f7;
    --filter-header-hover-bg: #eee;
    --filter-link-color: #0066cc;
    --filter-link-hover-color: #005fa3;
    --filter-link-hover-bg: #f0f8ff;
    --filter-link-selected-bg: #e6f3ff;
    --filter-link-selected-color: #004c87;
    --responsive-border-bottom: #ccc;
}

/* Dark Mode - Activated by System Preference or Manual Toggle */
@media (prefers-color-scheme: dark) {
    :root {
        --body-background: #1a1a1a;
        --main-text-color: #ccc;
        --heading-color: #e0e0e0;
        --intro-heading-border: #333;
        --card-background: #2a2a2a;
        --card-border: #444;
        --card-shadow: 0 4px 10px rgba(0,0,0,0.2);
        --diff-card-background: #222;
        --diff-card-border: #333;
        --diff-card-shadow: 0 1px 5px rgba(0,0,0,0.1);
        --strong-text-color: #e0e0e0;
        --sidebar-border-color: #444;
        --sidebar-menu-border: #444;
        --sidebar-link-color: #aaa;
        --sidebar-link-hover-bg: #2a2a2a;
        --sidebar-link-hover-color: #e0e0e0;
        --sidebar-active-bg: #293846;
        --sidebar-active-color: #92b0d3;
        --sidebar-active-border: #79a1d1;
        --filter-header-bg: #282828;
        --filter-header-hover-bg: #333;
        --filter-link-color: #79a1d1;
        --filter-link-hover-color: #5580a8;
        --filter-link-hover-bg: #2a3a4a;
        --filter-link-selected-bg: #293846;
        --filter-link-selected-color: #92b0d3;
        --responsive-border-bottom: #444;
    }
}

body[data-theme='dark'] {
    /* Manual Dark Mode Override */
    --body-background: #1a1a1a;
    --main-text-color: #ccc;
    --heading-color: #e0e0e0;
    --intro-heading-border: #333;
    --card-background: #2a2a2a;
    --card-border: #444;
    --card-shadow: 0 4px 10px rgba(0,0,0,0.2);
    --diff-card-background: #222;
    --diff-card-border: #333;
    --diff-card-shadow: 0 1px 5px rgba(0,0,0,0.1);
    --strong-text-color: #e0e0e0;
    --sidebar-border-color: #444;
    --sidebar-menu-border: #444;
    --sidebar-link-color: #aaa;
    --sidebar-link-hover-bg: #2a2a2a;
    --sidebar-link-hover-color: #e0e0e0;
    --sidebar-active-bg: #293846;
    --sidebar-active-color: #92b0d3;
    --sidebar-active-border: #79a1d1;
    --filter-header-bg: #282828;
    --filter-header-hover-bg: #333;
    --filter-link-color: #79a1d1;
    --filter-link-hover-color: #5580a8;
    --filter-link-hover-bg: #2a3a4a;
    --filter-link-selected-bg: #293846;
    --filter-link-selected-color: #92b0d3;
    --responsive-border-bottom: #444;
}

/* --- Core Layout & Global Styles (from reldates.css) --- */
body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--body-background);
    color: var(--main-text-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* ---------- MAIN CONTENT LAYOUT ---------- */
.game-content-wrapper {
    display: flex;
    flex-direction: row;
    align-items: flex-start;
    min-height: 100vh;
    padding: 140px 20px 40px;
    gap: 20px;
    box-sizing: border-box;
}

/* --- Sidebar Styles (from reldates.css) --- */
.filter-sidebar {
    width: 300px;
    padding: 0 20px 40px;
    box-sizing: border-box;
    border-right: 2px dotted var(--sidebar-border-color);
    flex-shrink: 0;
    position: sticky;
    top: 100px;
    z-index: 999;
    transition: border-color 0.3s ease;
}

.sidebar-menu {
    margin-bottom: 20px;
    padding-bottom: 20px;
    border-bottom: 2px dotted var(--sidebar-menu-border);
    margin-top: 10px;
    transition: border-color 0.3s ease;
}

.sidebar-menu .sidebar-item {
    display: block;
    padding: 10px 15px;
    text-decoration: none;
    color: var(--sidebar-link-color);
    font-weight: 500;
    transition: background-color 0.2s ease, color 0.2s ease;
    border-radius: 4px;
}

.sidebar-menu .sidebar-item:hover {
    background-color: var(--sidebar-link-hover-bg);
    color: var(--sidebar-link-hover-color);
}

.sidebar-menu .sidebar-item.active {
    background-color: var(--sidebar-active-bg);
    color: var(--sidebar-active-color);
    font-weight: bold;
    border-left: 4px solid var(--sidebar-active-border);
    padding-left: 11px;
}

.sidebar-menu .sidebar-item.active:hover {
    background-color: var(--sidebar-active-bg);
}

.sidebar-menu .sidebar-item:not(a) {
    cursor: default;
}

/* Filter styling */
.filter-sidebar h3 {
    font-size: 18px;
    margin-top: 20px;
    margin-bottom: 10px;
    color: var(--heading-color);
    transition: color 0.3s ease;
}

.filter-sidebar h3:first-child {
    margin-top: 0;
}

.filter-sidebar ul {
    list-style-type: none;
    padding-left: 0;
    margin-left: 0;
    margin-bottom: 20px;
}

.filter-sidebar li {
    margin-bottom: 5px;
}

.filter-sidebar a {
    color: var(--filter-link-color);
    text-decoration: none;
    display: block;
    padding: 5px 10px;
    border-radius: 4px;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.filter-sidebar a:hover {
    color: var(--filter-link-hover-color);
    background-color: var(--filter-link-hover-bg);
}

.filter-sidebar a.selected {
    font-weight: bold;
    color: var(--filter-link-selected-color);
    background-color: var(--filter-link-selected-bg);
}

/* === Collapsible Filter Styles (THESE WERE MISSING) === */
.collapsible-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
}

.collapsible-content.expanded {
    max-height: 500px;
}

.collapsible-header {
    cursor: pointer;
    user-select: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px;
    border-bottom: 1px solid var(--sidebar-menu-border);
    background-color: var(--filter-header-bg);
    margin-bottom: 10px;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.collapsible-header:hover {
    background-color: var(--filter-header-hover-bg);
}

.collapsible-header.expanded .toggle-icon {
    transform: rotate(180deg);
    transition: transform 0.3s ease-out;
}

.toggle-icon {
    font-size: 1.2em;
    font-weight: bold;
    line-height: 1;
    transition: transform 0.3s ease-out;
    color: var(--main-text-color);
}

/* --- Content Styles --- */
.main-content-area {
    flex: 1;
    padding: 0 0 20px 20px;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.intro-heading-section h1 {
    margin-top: 0;
    margin-bottom: 5px;
    color: var(--heading-color);
    font-size: 2em;
    border-bottom: 3px solid var(--intro-heading-border);
    padding-bottom: 10px;
    transition: color 0.3s ease, border-color 0.3s ease;
}

.intro-heading-section p {
    margin-top: 5px;
    margin-bottom: 0;
    line-height: 1.6;
    color: var(--main-text-color);
    transition: color 0.3s ease;
}

#differences-container {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.grpid-platform-group-card {
    background-color: var(--card-background);
    border: 1px solid var(--card-border);
    border-radius: 10px;
    box-shadow: var(--card-shadow);
    padding: 25px;
    transition: background-color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

.platform-card-header {
    border-bottom: 1px solid var(--card-border);
    margin-bottom: 15px;
    transition: border-color 0.3s ease;
}

.platform-card-header h3 {
    font-size: 24px;
    margin: 0;
    color: var(--heading-color);
    transition: color 0.3s ease;
}

.difference-card {
    background-color: var(--diff-card-background);
    border: 1px solid var(--diff-card-border);
    border-radius: 8px;
    padding: 20px;
    margin-top: 20px;
    box-shadow: var(--diff-card-shadow);
    transition: background-color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

.difference-card p {
    margin-bottom: 8px;
    line-height: 1.6;
    color: var(--main-text-color);
    transition: color 0.3s ease;
}

.difference-card p strong {
    color: var(--strong-text-color);
    transition: color 0.3s ease;
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .game-content-wrapper {
        flex-direction: column;
    }

    .filter-sidebar {
        width: 100%;
        border-right: none;
        border-bottom: 2px dotted var(--responsive-border-bottom);
        margin-bottom: 20px;
        transition: border-color 0.3s ease;
    }

    .main-content-area {
        padding-left: 0;
    }
}