Constant DEFAULT_CSS 

pub const DEFAULT_CSS: &str = r#"/* CSS Variables for Light/Dark Themes */
:root {
    --color-primary: #3B82F6;
    --color-primary-hover: #2563EB;
    --color-secondary: #60A5FA;
    --color-cta: #F97316;
    --color-cta-hover: #EA580C;
    --color-bg: #F8FAFC;
    --color-bg-secondary: #FFFFFF;
    --color-text: #1E293B;
    --color-text-secondary: #475569;
    --color-text-muted: #64748B;
    --color-border: #E2E8F0;
    --color-code-bg: #F1F5F9;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    color-scheme: light;
}

[data-theme="dark"] {
    --color-primary: #60A5FA;
    --color-primary-hover: #93C5FD;
    --color-secondary: #3B82F6;
    --color-cta: #FB923C;
    --color-cta-hover: #FDBA74;
    --color-bg: #0F172A;
    --color-bg-secondary: #1E293B;
    --color-text: #F1F5F9;
    --color-text-secondary: #CBD5E1;
    --color-text-muted: #94A3B8;
    --color-border: #334155;
    --color-code-bg: #1E293B;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4), 0 2px 4px -2px rgb(0 0 0 / 0.3);
    color-scheme: dark;
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --color-primary: #60A5FA;
        --color-primary-hover: #93C5FD;
        --color-secondary: #3B82F6;
        --color-cta: #FB923C;
        --color-cta-hover: #FDBA74;
        --color-bg: #0F172A;
        --color-bg-secondary: #1E293B;
        --color-text: #F1F5F9;
        --color-text-secondary: #CBD5E1;
        --color-text-muted: #94A3B8;
        --color-border: #334155;
        --color-code-bg: #1E293B;
        --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
        --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4), 0 2px 4px -2px rgb(0 0 0 / 0.3);
        color-scheme: dark;
    }
}

/* Reset & Base */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    font-weight: 400;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color 0.2s ease, color 0.2s ease;
}

/* Layout */
.container {
    width: 100%;
    max-width: 720px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* Header */
header {
    position: sticky;
    top: 0;
    z-index: 50;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    background-color: rgba(248, 250, 252, 0.9);
}

[data-theme="dark"] header {
    background-color: rgba(15, 23, 42, 0.9);
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) header {
        background-color: rgba(15, 23, 42, 0.9);
    }
}

header nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
}

.site-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    letter-spacing: -0.025em;
    transition: color 0.2s ease;
}

.site-title:hover {
    color: var(--color-primary);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-links a {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

.nav-links a:hover {
    color: var(--color-primary);
}

/* Theme Toggle Button */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 0.5rem;
    border: 1px solid var(--color-border);
    background-color: var(--color-bg-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.theme-toggle:hover {
    border-color: var(--color-primary);
    background-color: var(--color-bg);
}

.theme-toggle svg {
    width: 1.125rem;
    height: 1.125rem;
    color: var(--color-text-secondary);
}

.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }

[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .theme-toggle .icon-sun { display: block; }
    :root:not([data-theme="light"]) .theme-toggle .icon-moon { display: none; }
}

/* Language Switcher */
.lang-switcher {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 0.5rem;
    border: 1px solid var(--color-border);
    background-color: var(--color-bg-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    outline: none;
}

.lang-switcher .lang-code {
    font-size: 0.6875rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.lang-switcher:hover,
.lang-switcher:focus {
    border-color: var(--color-primary);
    background-color: var(--color-bg);
}

.lang-switcher .lang-dropdown {
    display: none;
    position: absolute;
    top: calc(100% + 0.5rem);
    right: 0;
    min-width: 8rem;
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: 0.5rem;
    box-shadow: var(--shadow-md);
    overflow: hidden;
    z-index: 100;
}

.lang-switcher:focus-within .lang-dropdown,
.lang-switcher:hover .lang-dropdown {
    display: block;
}

.lang-dropdown a {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 0.875rem;
    font-size: 0.8125rem;
    color: var(--color-text);
    text-decoration: none;
    transition: background-color 0.15s ease;
}

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

.lang-dropdown a.active {
    color: var(--color-primary);
    font-weight: 500;
}

.lang-dropdown .lang-name {
    flex: 1;
}

.lang-dropdown .lang-flag {
    font-size: 1rem;
}

/* Navigation Actions */
.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Search Styles */
.search-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.search-input {
    width: 0;
    padding: 0;
    border: none;
    background: transparent;
    opacity: 0;
    transition: all 0.2s ease;
    font-size: 0.875rem;
    color: var(--color-text);
}

.search-wrapper.active .search-input {
    width: 150px;
    padding: 0.5rem 0.75rem;
    padding-right: 2.25rem;
    opacity: 1;
    border: 1px solid var(--color-border);
    border-radius: 0.5rem;
    background-color: var(--color-bg-secondary);
}

.search-wrapper.active .search-input:focus {
    outline: none;
    border-color: var(--color-primary);
}

.search-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.25rem;
    height: 2.25rem;
    border-radius: 0.5rem;
    border: 1px solid var(--color-border);
    background-color: var(--color-bg-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    position: relative;
    z-index: 1;
}

.search-wrapper.active .search-btn {
    position: absolute;
    right: 0;
    border: none;
    background: transparent;
    width: 2rem;
    height: 100%;
}

.search-btn:hover {
    border-color: var(--color-primary);
    background-color: var(--color-bg);
}

.search-wrapper.active .search-btn:hover {
    border-color: transparent;
    background-color: transparent;
}

.search-btn svg {
    width: 1.125rem;
    height: 1.125rem;
    color: var(--color-text-secondary);
}

.search-results {
    display: none;
    position: absolute;
    top: calc(100% + 0.5rem);
    right: 0;
    width: 300px;
    max-height: 400px;
    overflow-y: auto;
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: 0.5rem;
    box-shadow: var(--shadow-md);
    z-index: 100;
}

.search-results.show {
    display: block;
}

.search-result-item {
    display: block;
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--color-border);
    text-decoration: none;
    transition: background-color 0.15s ease;
}

.search-result-item:last-child {
    border-bottom: none;
}

.search-result-item:hover {
    background-color: var(--color-bg);
}

.search-result-title {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: 0.25rem;
}

.search-result-snippet {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.search-no-results {
    padding: 1rem;
    text-align: center;
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

/* Main Content */
main {
    flex: 1;
    padding: 3rem 0;
}

/* Footer */
footer {
    padding: 2rem 0;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

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

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--color-text);
}

h1 { font-size: 2rem; letter-spacing: -0.025em; }
h2 { font-size: 1.5rem; margin-top: 2rem; margin-bottom: 1rem; }
h3 { font-size: 1.25rem; margin-top: 1.5rem; margin-bottom: 0.75rem; }

p {
    margin-bottom: 1.25rem;
}

a {
    color: var(--color-primary);
    transition: color 0.2s ease;
}

a:hover {
    color: var(--color-primary-hover);
}

/* Code */
code {
    font-family: 'JetBrains Mono', 'Fira Code', monospace;
    font-size: 0.875em;
    background-color: var(--color-code-bg);
    padding: 0.125rem 0.375rem;
    border-radius: 0.25rem;
}

pre {
    background-color: var(--color-code-bg);
    padding: 1rem;
    border-radius: 0.5rem;
    overflow-x: auto;
    margin: 1.5rem 0;
}

pre code {
    background: none;
    padding: 0;
    font-size: 0.8125rem;
    line-height: 1.6;
}

/* Article */
article.post header,
article.page h1 {
    margin-bottom: 2rem;
}

article.post header h1 {
    margin-bottom: 0.5rem;
}

article.post header time {
    display: block;
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

article .content {
    font-size: 1rem;
}

article .content img {
    max-width: 100%;
    height: auto;
    border-radius: 0.5rem;
    margin: 1.5rem 0;
}

article .content blockquote {
    border-left: 3px solid var(--color-primary);
    padding-left: 1rem;
    margin: 1.5rem 0;
    color: var(--color-text-secondary);
    font-style: italic;
}

article .content ul,
article .content ol {
    margin: 1rem 0 1.5rem 1.5rem;
}

article .content li {
    margin-bottom: 0.5rem;
}

/* Tags */
.tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 0.75rem;
}

.tag {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.625rem;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-primary);
    background-color: color-mix(in srgb, var(--color-primary) 10%, transparent);
    border-radius: 9999px;
    text-decoration: none;
    transition: all 0.2s ease;
}

.tag:hover {
    background-color: color-mix(in srgb, var(--color-primary) 20%, transparent);
}

/* Post List */
.post-list ul {
    list-style: none;
}

.post-list li {
    padding: 1.25rem 0;
    border-bottom: 1px solid var(--color-border);
}

.post-list li:first-child {
    padding-top: 0;
}

.post-item-header {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 0.375rem;
}

.post-item-header a {
    font-size: 1.0625rem;
    font-weight: 500;
    color: var(--color-text);
    text-decoration: none;
    transition: color 0.15s ease;
}

.post-item-header a:hover {
    color: var(--color-primary);
}

.post-item-header time {
    flex-shrink: 0;
    font-size: 0.8125rem;
    color: var(--color-text-muted);
}

.post-item-description {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    line-height: 1.5;
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--color-border);
}

.pagination a,
.pagination span {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 2.25rem;
    height: 2.25rem;
    padding: 0 0.75rem;
    font-size: 0.875rem;
    border-radius: 0.375rem;
    text-decoration: none;
    transition: all 0.15s ease;
}

.pagination a {
    color: var(--color-text-secondary);
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
}

.pagination a:hover {
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.pagination span.current {
    color: white;
    background-color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.pagination span.ellipsis {
    color: var(--color-text-muted);
    border: none;
    background: none;
}

/* Tags Cloud */
.tags-cloud {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tags-cloud a {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.375rem 0.75rem;
    font-size: 0.875rem;
    color: var(--color-text);
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: 9999px;
    text-decoration: none;
    transition: all 0.2s ease;
}

.tags-cloud a:hover {
    color: var(--color-primary);
    border-color: var(--color-primary);
}

.tags-cloud .count {
    font-size: 0.75rem;
    color: var(--color-text-muted);
}

/* Categories List */
.categories-list {
    list-style: none;
    padding: 0;
}

.categories-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--color-border);
}

.categories-list li:first-child {
    padding-top: 0;
}

.categories-list .count {
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

/* Archives */
.archives h1 {
    margin-bottom: 2rem;
}

.archive-year {
    margin-bottom: 2rem;
}

.archive-year h2 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
    color: var(--color-primary);
}

.archive-year ul {
    list-style: none;
    padding: 0;
}

.archive-year li {
    display: flex;
    align-items: baseline;
    gap: 1rem;
    padding: 0.5rem 0;
}

.archive-date {
    flex-shrink: 0;
    font-size: 0.8125rem;
    color: var(--color-text-muted);
    font-variant-numeric: tabular-nums;
    min-width: 3rem;
}

.archive-year li a {
    color: var(--color-text);
    text-decoration: none;
    transition: color 0.15s ease;
}

.archive-year li a:hover {
    color: var(--color-primary);
}

/* Section List */
.section-list h1 {
    margin-bottom: 0.5rem;
}

.section-description {
    color: var(--color-text-muted);
    margin-bottom: 1.5rem;
}

/* Responsive */
@media (max-width: 640px) {
    html { font-size: 15px; }
    h1 { font-size: 1.75rem; }
    h2 { font-size: 1.375rem; }
    .container { padding: 0 1rem; }
    main { padding: 2rem 0; }
    .nav-links { gap: 0.75rem; }
    .nav-links > a { font-size: 0.8125rem; }
    .post-item-header { flex-direction: column; gap: 0.25rem; }
    .nav-actions { gap: 0.375rem; }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}
"#;

Default CSS styles. Extracted from the inline styles in template.rs for better caching.