/* =================================
    CSS VARIABLES (Light & Dark Mode)
    ================================= */

:root {
    /* Light Mode */
    --body-background: #f8f8f8;
    --main-text-color: #333;
    --sidebar-border-color: #ccc;
    --sidebar-link-color: #333;
    --sidebar-link-hover-color: #0078d7;
    --heading-border-color: #0078d7;
}

/* Dark Mode - Activated by System Preference or Manual Toggle */
@media (prefers-color-scheme: dark) {
    :root {
        --body-background: #1a1a1a;
        --main-text-color: #e0e0e0;
        --sidebar-border-color: #444;
        --sidebar-link-color: #e0e0e0;
        --sidebar-link-hover-color: #79a1d1;
        --heading-border-color: #62707D;
    }
}

body[data-theme='dark'] {
    --body-background: #1a1a1a;
    --main-text-color: #e0e0e0;
    --sidebar-border-color: #444;
    --sidebar-link-color: #e0e0e0;
    --sidebar-link-hover-color: #79a1d1;
    --heading-border-color: #62707D;
}

/* =================================
    General Styling
    ================================= */

.page-wrapper {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--body-background);
    color: var(--main-text-color);
    display: flex;
    min-height: calc(100vh + 80px);
    margin: 0;
    padding: 0;
    margin-top: 80px;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.page-sidebar {
    position: fixed;
    top: 80px;
    bottom: 0;
    width: 300px;
    border-right: 2px dotted var(--sidebar-border-color);
    padding: 20px;
    box-sizing: border-box;
    overflow-y: auto;
    flex-shrink: 0;
    z-index: 100;
    transition: border-color 0.3s ease;
}

.page-sidebar ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.page-sidebar li {
    margin-bottom: 15px;
}

.page-sidebar a {
    text-decoration: none;
    color: var(--sidebar-link-color);
    font-weight: 600;
    font-size: 16px;
    display: inline-block;
    transition: color 0.3s ease;
}

.page-sidebar a:hover {
    color: var(--sidebar-link-hover-color);
}

body {
    margin: 0;
}

.page-content {
    flex-grow: 1;
    padding: 20px 40px;
    background-color: var(--body-background);
    color: var(--main-text-color);
    max-width: 900px;
    margin-left: calc(300px + 20px); /* Sidebar width + padding */
    transition: background-color 0.3s ease, color 0.3s ease;
}

section {
    margin-bottom: 60px;
}

h2 {
    border-bottom: 2px solid var(--heading-border-color);
    padding-bottom: 6px;
    margin-bottom: 16px;
    transition: border-color 0.3s ease;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}