/* ============================================
   Professional Dark Theme - Programmer Style
   ============================================ */

*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* Scrollbar styling — Chromium */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-secondary, #161616);
}
::-webkit-scrollbar-thumb {
    background: var(--border-primary, #2a2a2a);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted, #6a6a6a);
}

:root {
    /* Dark theme - refined, professional palette */
    --bg-primary: #0f0f0f;
    --bg-secondary: #161616;
    --bg-tertiary: #1c1c1c;
    --bg-elevated: #242424;
    
    --text-primary: #e8e8e8;
    --text-secondary: #a0a0a0;
    --text-muted: #6a6a6a;
    
    --accent-primary: #c9a227;
    --accent-hover: #ddb52f;
    --accent-subtle: rgba(201, 162, 39, 0.1);
    
    --border-primary: #2a2a2a;
    --border-subtle: #1f1f1f;
    
    --code-bg: #0a0a0a;
    --code-text: #e6b450;
    --code-comment: #6a737d;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
    
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    
    --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', 'Cascadia Code', 'Consolas', monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
}

html[data-theme='light'] {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f8f8;
    --bg-tertiary: #f0f0f0;
    --bg-elevated: #ffffff;
    
    --text-primary: #1a1a1a;
    --text-secondary: #4a4a4a;
    --text-muted: #8a8a8a;
    
    --accent-primary: #9a7d1c;
    --accent-hover: #7d6416;
    --accent-subtle: rgba(154, 125, 28, 0.08);
    
    --border-primary: #e0e0e0;
    --border-subtle: #eaeaea;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
}

/* Light mode: keep code blocks dark for contrast */
html[data-theme='light'] .content pre,
html[data-theme='light'] .content code {
    --code-bg: #1e1e1e;
    --code-text: #e6b450;
    background-color: var(--code-bg);
    color: var(--code-text);
}

/* ============================================
   Base Styles
   ============================================ */

.hidden {
    display: none !important;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    /* Firefox scrollbar */
    scrollbar-width: thin;
    scrollbar-color: var(--border-primary) var(--bg-secondary);
}

body {
    font-family: var(--font-mono);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

/* ============================================
   Layout
   ============================================ */

.site-container {
    max-width: 900px;
    width: 100%;
    margin: 0 auto;
    padding: 0 2rem;
}

main {
    flex: 1;
    padding: 3rem 2rem;
    max-width: 1100px;
    margin: 0 auto;
    width: 100%;
}

.content {
    flex: 1;
    padding: 3rem 0;
}

/* ============================================
   Header
   ============================================ */

header {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-primary);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.header-left h1 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin: 0 0 0.5rem;
}

.header-left h1 a {
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.header-left h1 a:hover {
    color: var(--accent-primary);
}

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

nav a {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    text-transform: lowercase;
    padding: 0.25rem 0;
    border-bottom: 1px solid transparent;
    transition: all var(--transition-fast);
}

nav a:hover, nav a.active {
    color: var(--accent-primary);
    border-bottom-color: var(--accent-primary);
}

/* Dropdown menu styles */
.nav-dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-trigger {
    cursor: pointer;
    user-select: none;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    margin-top: 0.5rem;
    min-width: 200px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 6px;
    padding: 0.5rem 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: all var(--transition-base);
    z-index: 1000;
}

.nav-dropdown:hover .dropdown-menu,
.nav-dropdown.active .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--text-secondary);
    border-bottom: none !important;
    transition: all var(--transition-fast);
}

.dropdown-menu a:hover {
    background: var(--bg-tertiary);
    color: var(--accent-primary);
}

.header-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.toggle-group {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    font-size: var(--font-size-sm);
}

.lang-link {
    color: var(--text-muted);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    transition: all var(--transition-fast);
}

.lang-link:hover {
    color: var(--text-primary);
}

.lang-link.active {
    color: var(--accent-primary);
    background: var(--accent-subtle);
}

.toggle-separator {
    color: var(--text-muted);
}

.theme-switch {
    background: transparent;
    border: 1px solid var(--border-primary);
    color: var(--text-secondary);
    padding: 0.5rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
}

.theme-switch:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

#theme-toggle {
    background: transparent;
    border: 1px solid var(--border-primary);
    color: var(--text-secondary);
    padding: 0.5rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
}

#theme-toggle:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4 {
    font-weight: 600;
    line-height: 1.3;
    margin: 2rem 0 1rem;
    letter-spacing: -0.02em;
}

h1 { font-size: var(--font-size-3xl); }
h2 { font-size: var(--font-size-2xl); }
h3 { font-size: var(--font-size-xl); }
h4 { font-size: var(--font-size-lg); }

p {
    margin-bottom: 1.25rem;
    color: var(--text-secondary);
}

strong {
    color: var(--text-primary);
    font-weight: 600;
}

hr {
    border: none;
    border-top: 1px solid var(--border-primary);
    margin: 2rem 0;
}

ul, ol {
    margin-bottom: 1.25rem;
    padding-left: 1.5rem;
    color: var(--text-secondary);
}

li {
    margin-bottom: 0.5rem;
}

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

/* ============================================
   Code Blocks
   ============================================ */

code {
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    background: var(--code-bg);
    color: var(--code-text);
    padding: 0.2em 0.4em;
    border-radius: 4px;
}

pre {
    background: var(--code-bg);
    padding: 1.5rem;
    border-radius: 8px;
    overflow-x: auto;
    margin: 1.5rem 0;
    border: 1px solid var(--border-primary);
}

pre code {
    padding: 0;
    background: transparent;
}

/* ============================================
   Details / Accordion
   ============================================ */

details {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    margin: 1rem 0;
    overflow: hidden;
}

summary {
    padding: 1rem 1.25rem;
    cursor: pointer;
    font-weight: 500;
    color: var(--text-primary);
    transition: background var(--transition-fast);
    user-select: none;
}

summary:hover {
    background: var(--bg-elevated);
}

details[open] summary {
    border-bottom: 1px solid var(--border-primary);
}

details > *:not(summary) {
    padding: 1.25rem;
}

/* ============================================
   Footer
   ============================================ */

footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-primary);
    padding: 2rem;
    margin-top: auto;
}

footer .footer-content {
    max-width: 1100px;
    margin: 0 auto;
}

.footer-main {
    margin-bottom: 1.5rem;
}

.site-info {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: 1rem;
}

.contact-links {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    align-items: center;
}

.contact-links a {
    color: var(--text-muted);
    font-size: var(--font-size-sm);
    transition: color var(--transition-fast);
}

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

.footer-sep {
    color: var(--text-muted);
}

.footer-bottom {
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-subtle);
}

.footer-bottom p {
    margin-bottom: 0.25rem;
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.footer-tech {
    font-size: var(--font-size-xs);
}

.footer-tech a {
    color: var(--accent-primary);
}

/* ============================================
   Home Page Hero
   ============================================ */

.hero {
    text-align: left;
    padding: 3rem 0;
}

.hero h1 {
    margin-top: 0;
    margin-bottom: 0.5rem;
}

.hero .subtitle {
    color: var(--text-secondary);
    font-size: var(--font-size-lg);
    margin-bottom: 2rem;
}

/* ============================================
   Project & Publication Cards
   ============================================ */

.card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    transition: all var(--transition-normal);
}

.card:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-md);
}

.card h3 {
    margin-top: 0;
    margin-bottom: 0.75rem;
}

.card-meta {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    margin-bottom: 1rem;
}

/* ============================================
   Contact Form
   ============================================ */

.contact-form {
    width: 100%;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
    font-size: var(--font-size-sm);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-primary);
    border-radius: 6px;
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: var(--font-size-base);
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-subtle);
}

.form-group textarea {
    min-height: 150px;
    resize: vertical;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-muted);
}

button {
    background: var(--accent-primary);
    color: var(--bg-primary);
    padding: 0.875rem 2rem;
    border: none;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-transform: lowercase;
}

button:hover:not(:disabled) {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ============================================
   Blog Posts
   ============================================ */

.post-list {
    list-style: none;
    padding: 0;
}

.post-item {
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-subtle);
}

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

.post-date {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

.post-title {
    font-size: var(--font-size-lg);
    font-weight: 500;
    margin: 0;
}

.post-title a {
    color: var(--text-primary);
}

.post-title a:hover {
    color: var(--accent-primary);
}

.post-tags {
    margin-top: 0.5rem;
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.tag {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    background: var(--bg-tertiary);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
}

/* ============================================
   Tag List (Taxonomy)
   ============================================ */

.tag-list {
    list-style: none;
    padding: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.tag-list li {
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 6px;
    padding: 0.5rem 1rem;
    transition: all var(--transition-fast);
}

.tag-list li:hover {
    border-color: var(--accent-primary);
}

.tag-list a {
    color: var(--text-primary);
    font-weight: 500;
}

.tag-count {
    color: var(--text-muted);
    font-size: var(--font-size-sm);
    margin-left: 0.25rem;
}

/* ============================================
   Responsive
   ============================================ */

@media (max-width: 768px) {
    header {
        padding: 1rem;
    }
    
    .header-content {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .header-left {
        width: 100%;
    }
    
    .header-left h1 {
        font-size: var(--font-size-base);
        margin-bottom: 0.75rem;
    }
    
    nav {
        width: 100%;
        gap: 1rem;
    }
    
    .header-right {
        width: 100%;
        justify-content: space-between;
        margin-top: 0.5rem;
    }
    
    main {
        padding: 2rem 1rem;
    }
    
    footer {
        padding: 1.5rem 1rem;
    }
    
    .footer-content {
        text-align: center;
    }
    
    .contact-links {
        justify-content: center;
    }
    
    h1 { font-size: var(--font-size-2xl); }
    h2 { font-size: var(--font-size-xl); }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
    
    nav {
        gap: 0.75rem;
    }
    
    nav a {
        font-size: var(--font-size-xs);
    }
}