/* ═══ CSS Custom Properties (Light Mode) ═══ */
:root {
    --bg-body-1: #f7f7f7;
    --bg-body-2: #eaeaea;
    --bg-card: #ffffff;
    --bg-nav: #2d2d2d;
    --bg-nav-hover: #454545;
    --bg-banner: #eaeaea;
    --bg-dropdown: #f5f5f5;
    --bg-dropdown-hover: #eaeaea;
    --bg-code-inline: #f0f0f0;
    --bg-code-block: #f5f5f5;
    --bg-footer: #2d2d2d;
    --text-primary: #333;
    --text-secondary: #555;
    --text-nav: #f5f5f5;
    --text-code-inline: #b07c00;
    --text-code-block: #333;
    --text-banner-title: #333;
    --text-heading: #444;
    --text-footer: #f5f5f5;
    --shadow-sm: rgba(0, 0, 0, 0.05);
    --shadow-md: rgba(0, 0, 0, 0.1);
    --border-color: #ddd;
    --tag-bg: #e8e8e8;
    --tag-text: #555;
    --toc-bg: #f5f5f5;
}

/* ═══ Dark Mode ═══ */
[data-theme="dark"] {
    --bg-body-1: #121218;
    --bg-body-2: #1a1a24;
    --bg-card: #1e1e2a;
    --bg-nav: #0f0f18;
    --bg-nav-hover: #252535;
    --bg-banner: #161620;
    --bg-dropdown: #1e1e2a;
    --bg-dropdown-hover: #2a2a3a;
    --bg-code-inline: #2a2a3a;
    --bg-code-block: #252535;
    --bg-footer: #0f0f18;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0b0;
    --text-nav: #d0d0d0;
    --text-code-inline: #f0c040;
    --text-code-block: #e0e0e0;
    --text-banner-title: #e0e0e0;
    --text-heading: #c0c0d0;
    --text-footer: #d0d0d0;
    --shadow-sm: rgba(0, 0, 0, 0.2);
    --shadow-md: rgba(0, 0, 0, 0.3);
    --border-color: #333348;
    --tag-bg: #2a2a3a;
    --tag-text: #b0b0c0;
    --toc-bg: #252535;
}

/* General Reset */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* Smooth Scroll */
html {
    scroll-behavior: smooth;
}

/* Body and Font Styles */
body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-primary);
    line-height: 1.8;
    display: flex;
    flex-direction: column;
    align-items: center;
    background: linear-gradient(to bottom right, var(--bg-body-1), var(--bg-body-2));
    min-height: 100vh;
    margin: 0;
    transition: background 0.3s ease, color 0.3s ease;
}

/* Navigation Menu */
nav {
    width: 100%;
    background-color: var(--bg-nav);
    padding: 1rem 0;
    box-shadow: 0 4px 8px var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color 0.3s ease;
}

nav ul {
    list-style-type: none;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2rem;
}

nav ul li {
    position: relative;
}

nav ul li a {
    color: var(--text-nav);
    text-decoration: none;
    padding: 0.75rem 1.25rem;
    font-weight: bold;
    transition: all 0.3s ease;
    border-radius: 5px;
}

nav ul li a:hover {
    background-color: var(--bg-nav-hover);
    color: #ffffff;
    transform: scale(1.05);
}

/* Dropdown Menu */
.dropdown-content {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: var(--bg-dropdown);
    min-width: 180px;
    box-shadow: 0px 8px 16px var(--shadow-md);
    z-index: 1;
    border-radius: 5px;
    transition: background-color 0.3s ease;
}

.dropdown-content a {
    color: var(--text-primary);
    padding: 0.75rem 1.25rem;
    display: block;
    text-decoration: none;
    transition: all 0.3s ease;
    font-weight: normal;
}

.dropdown-content a:hover {
    background-color: var(--bg-dropdown-hover);
}

.dropdown:hover .dropdown-content {
    display: block;
}

/* Sub-category heading inside dropdown */
.dropdown-heading {
    display: block;
    padding: 0.5rem 1.25rem 0.25rem;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05rem;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: 0.25rem;
}

.dropdown-heading:first-child {
    border-top: none;
    margin-top: 0;
}

/* Theme Toggle Button */
#theme-toggle {
    background: none;
    border: none;
    color: var(--text-nav);
    cursor: pointer;
    font-size: 1.3rem;
    padding: 0.5rem 0.75rem;
    border-radius: 5px;
    box-shadow: none;
    transition: transform 0.3s ease, background-color 0.3s ease;
    line-height: 1;
}

#theme-toggle:hover {
    transform: scale(1.2);
    background-color: var(--bg-nav-hover);
    box-shadow: none;
}

/* Banner */
#banner {
    background: var(--bg-banner);
    color: var(--text-primary);
    padding: 3rem;
    text-align: center;
    width: 100%;
    box-shadow: 0 4px 8px var(--shadow-sm);
    border-bottom-left-radius: 15px;
    border-bottom-right-radius: 15px;
    transition: background 0.3s ease;
}

#banner h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: bold;
    color: var(--text-banner-title);
}

#banner p {
    font-size: 1.2rem;
    font-weight: 300;
    color: var(--text-secondary);
}

/* Main Content */
main {
    width: 80%;
    max-width: 1000px;
    background: var(--bg-card);
    margin: 2rem auto;
    padding: 2rem;
    box-shadow: 0 6px 12px var(--shadow-sm);
    border-radius: 10px;
    transition: all 0.3s ease;
}

main h1, main h2, main h3, main h4 {
    color: var(--text-heading);
    font-weight: bold;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

main h1 { font-size: 2rem; }

main p {
    margin: 1.5rem 0;
    font-size: 1.1rem;
    color: var(--text-primary);
}

main a {
    color: #0066cc;
}

[data-theme="dark"] main a {
    color: #6db3f2;
}

main img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin: 1rem 0;
}

/* Inline and Block Code Styling */
code {
    background-color: var(--bg-code-inline);
    color: var(--text-code-inline);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.95rem;
    transition: background-color 0.3s ease, color 0.3s ease;
}

pre code {
    display: block;
    padding: 1rem;
    background-color: var(--bg-code-block);
    color: var(--text-code-block);
    border-radius: 5px;
    overflow-x: auto;
    font-size: 1rem;
    box-shadow: 0 4px 8px var(--shadow-sm);
}

/* Let highlight.js handle colors inside code blocks */
pre code.hljs {
    background-color: var(--bg-code-block);
}

/* Table of Contents */
.toc {
    background: var(--toc-bg);
    border-radius: 8px;
    padding: 1rem 1.5rem;
    margin-bottom: 2rem;
    transition: background 0.3s ease;
}

.toc details summary {
    font-weight: bold;
    cursor: pointer;
    margin-bottom: 0.5rem;
    font-size: 1.05rem;
    color: var(--text-heading);
}

.toc ul {
    list-style: none;
    padding-left: 0;
    margin: 0;
}

.toc li {
    margin: 0.3rem 0;
}

.toc li a {
    text-decoration: none;
    color: var(--text-secondary);
    transition: color 0.2s ease;
}

.toc li a:hover {
    color: var(--text-primary);
}

.toc-level-2 { padding-left: 1rem; }
.toc-level-3 { padding-left: 2rem; }
.toc-level-4 { padding-left: 3rem; }

/* Article Metadata */
.article-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.article-date {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.tag {
    display: inline-block;
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.8rem;
    transition: background 0.3s ease, color 0.3s ease;
}

.article-tags {
    display: flex;
    gap: 0.4rem;
    flex-wrap: wrap;
}

/* Article List / Cards (articles.html) */
.article-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.article-card {
    padding: 1.5rem;
    background: var(--toc-bg);
    border-radius: 8px;
    transition: transform 0.2s ease, background 0.3s ease;
}

.article-card:hover {
    transform: translateY(-2px);
}

.article-card h3 {
    margin-top: 0;
    margin-bottom: 0.5rem;
}

.article-card h3 a {
    text-decoration: none;
    color: var(--text-heading);
}

.article-card h3 a:hover {
    text-decoration: underline;
}

.article-card time {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.article-card p {
    font-size: 1rem;
    margin: 0.5rem 0;
}

/* Blockquote */
blockquote {
    border-left: 4px solid var(--bg-nav);
    padding: 0.75rem 1.25rem;
    margin: 1rem 0;
    background: var(--toc-bg);
    border-radius: 0 5px 5px 0;
    color: var(--text-secondary);
    transition: background 0.3s ease;
}

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
}

th, td {
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    text-align: left;
}

th {
    background-color: var(--bg-nav);
    color: var(--text-nav);
    font-weight: bold;
}

td {
    background-color: var(--bg-card);
}

/* Lists */
main ul, main ol {
    margin: 1rem 0;
    padding-left: 2rem;
}

main li {
    margin: 0.4rem 0;
    font-size: 1.05rem;
}

/* Footer */
footer {
    background-color: var(--bg-footer);
    color: var(--text-footer);
    padding: 1rem;
    text-align: center;
    width: 100%;
    margin-top: auto;
    box-shadow: 0 -4px 8px var(--shadow-md);
    position: relative;
    transition: background-color 0.3s ease;
}

footer p {
    font-size: 0.9rem;
    letter-spacing: 0.05rem;
}

footer p a {
    color: var(--text-footer);
    text-decoration: none;
}

footer p a:hover {
    text-decoration: underline;
}

/* Button Styles */
button {
    background-color: var(--bg-nav);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    border-radius: 5px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 8px var(--shadow-md);
}

button:hover {
    background-color: var(--bg-nav-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px var(--shadow-md);
}

/* Social Media Links */
.social-links {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin: 1rem 0;
}

.social-links a {
    display: inline-block;
    width: 32px;
    height: 32px;
    transition: transform 0.3s ease;
}

.social-links a:hover {
    transform: scale(1.1);
}

.social-links img {
    width: 100%;
    height: auto;
    border-radius: 5px;
}

/* Responsive Design */
@media (max-width: 768px) {
    main {
        width: 95%;
        padding: 1.5rem;
    }

    nav ul {
        flex-direction: column;
        gap: 0.5rem;
    }

    nav ul li a {
        padding: 0.5rem 1rem;
    }

    #banner h1 {
        font-size: 2.2rem;
    }

    .toc {
        padding: 0.75rem 1rem;
    }

    .article-meta {
        flex-direction: column;
        align-items: flex-start;
    }
}

/* Focus states for keyboard navigation */
a:focus-visible,
button:focus-visible {
    outline: 2px solid #4a90d9;
    outline-offset: 2px;
}

/* Print styles */
@media print {
    nav, footer, #theme-toggle, .toc { display: none; }
    main { width: 100%; box-shadow: none; margin: 0; }
    body { background: #fff; }
}