/* ============================================
   Academic Researcher Theme
   ============================================ */

/* ============================================
   CSS Variables & Design Tokens
   ============================================ */
:root {
    /* Colors - Refined Professional Palette */
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-primary-light: #3b82f6;
    --color-secondary: #0f172a;
    --color-accent: #0d9488;

    --color-bg: #ffffff;
    --color-bg-secondary: #f8fafc;
    --color-bg-tertiary: #f1f5f9;
    --color-surface: #ffffff;
    --color-surface-elevated: #ffffff;

    --color-text: #0f172a;
    --color-text-secondary: #334155;
    --color-text-muted: #64748b;

    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;

    /* Gradients - Professional & Subtle */
    --gradient-primary: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    --gradient-accent: linear-gradient(135deg, #0d9488 0%, #2563eb 100%);
    --gradient-neural: linear-gradient(135deg, rgba(37, 99, 235, 0.05) 0%, rgba(13, 148, 136, 0.05) 100%);

    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', 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;
    --font-size-4xl: 2.25rem;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.05);
    --shadow-glow: 0 0 15px rgba(37, 99, 235, 0.2);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;

    /* Layout */
    --container-max-width: 1100px;
    --content-max-width: 850px;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --color-bg: #0f172a;
    --color-bg-secondary: #1e293b;
    --color-bg-tertiary: #334155;
    --color-surface: #1e293b;
    --color-surface-elevated: #334155;

    --color-text: #f8fafc;
    --color-text-secondary: #cbd5e1;
    --color-text-muted: #94a3b8;

    --color-border: #334155;
    --color-border-light: #475569;

    --gradient-neural: linear-gradient(135deg, rgba(37, 99, 235, 0.1) 0%, rgba(13, 148, 136, 0.1) 100%);
    --shadow-glow: 0 0 20px rgba(37, 99, 235, 0.3);
}

/* ============================================
   Base Styles
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: 1.75;
    color: var(--color-text);
    background: var(--color-bg);
    transition: background-color var(--transition-base), color var(--transition-base);
    position: relative;
    min-height: 100vh;
}

#neural-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    opacity: 0.3;
    pointer-events: none;
}

/* ============================================
   Typography
   ============================================ */
h1,
h2,
h3,
h4 {
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
    letter-spacing: -0.02em;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-xl);
}

h2 {
    font-size: 1.75rem;
    margin-top: var(--spacing-2xl);
    border-bottom: 2px solid var(--color-border-light);
    padding-bottom: var(--spacing-xs);
}

h3 {
    font-size: 1.25rem;
    margin-top: var(--spacing-xl);
}

p {
    margin-bottom: var(--spacing-lg);
}

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

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

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

code {
    font-family: var(--font-mono);
    font-size: 0.85em;
    background: var(--color-bg-tertiary);
    padding: 0.2em 0.4em;
    border-radius: var(--radius-sm);
    color: var(--color-primary);
}

pre {
    background: var(--color-bg-tertiary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin: var(--spacing-lg) 0;
    border: 1px solid var(--color-border);
}

/* ============================================
   Layout & Container
   ============================================ */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
}

.page-content {
    max-width: var(--content-max-width);
    margin: 0 auto;
}

/* ============================================
   Header & Navigation
   ============================================ */
.site-header {
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

[data-theme="dark"] .site-header {
    background: rgba(15, 23, 42, 0.8);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: nowrap;
    gap: var(--spacing-lg);
    width: 100%;
}

.site-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin: 0;
}

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

.site-subtitle {
    font-size: 0.8rem;
    color: var(--color-text-secondary);
    margin: 0;
    font-weight: 500;
}

.main-nav {
    display: flex;
    align-items: center;
    margin: 0;
    padding: 0;
    flex-shrink: 0;
}

.main-nav ul {
    display: flex;
    align-items: center;
    list-style: none;
    gap: var(--spacing-xl);
    margin: 0;
    padding: 0;
    flex-wrap: nowrap;
}

.main-nav li {
    display: flex;
    align-items: center;
    margin: 0;
    padding: 0;
    white-space: nowrap;
}

.main-nav a {
    color: var(--color-text-secondary);
    font-weight: 500;
    font-size: 0.9rem;
    line-height: 1;
}

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

#theme-toggle {
    background: none;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    width: 36px;
    height: 36px;
    margin: 0;
    padding: 0;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    line-height: 1;
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.nav-toggle-item {
    margin-left: var(--spacing-sm);
}

/* ============================================
   Home / Hero Section
   ============================================ */
.profile-section {
    display: flex;
    align-items: center;
    gap: var(--spacing-2xl);
    padding: var(--spacing-2xl) 0;
    margin-bottom: var(--spacing-2xl);
}

.profile-image-wrapper {
    flex-shrink: 0;
}

.profile-image {
    width: 180px;
    height: 180px;
    border-radius: var(--radius-xl);
    object-fit: cover;
    box-shadow: var(--shadow-xl);
    border: 4px solid var(--color-surface);
}

.profile-info h1 {
    margin-bottom: var(--spacing-xs);
    font-size: 2.25rem;
}

.profile-position {
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xs);
}

.profile-institution {
    font-size: 1rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
}

.profile-links {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.profile-link {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    border-bottom: 2px solid var(--color-border);
    padding-bottom: 2px;
}

.profile-link:hover {
    color: var(--color-primary);
    border-color: var(--color-primary);
}

/* ============================================
   Buttons & CTAs
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    padding: 0.6rem 1.25rem;
    background: var(--color-primary);
    color: white;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    transition: all var(--transition-fast);
    border: none;
    cursor: pointer;
}

.btn:hover {
    background: var(--color-primary-dark);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
    margin-left: var(--spacing-md);
}

.btn-secondary:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-primary-dark);
}

/* ============================================
   Sections & Cards
   ============================================ */
.research-area,
.project-item,
.cv-section {
    margin-bottom: var(--spacing-2xl);
}

.research-area h2 {
    border: none;
    padding: 0;
    margin-bottom: var(--spacing-sm);
}

.research-meta {
    font-size: 0.9rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.publication-card {
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid var(--color-border-light);
}

.publication-card:last-child {
    border-bottom: none;
}

.pub-title {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
    display: block;
}

.pub-venue {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--color-text);
    margin-right: var(--spacing-sm);
}

.pub-year {
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

.pub-authors {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-top: var(--spacing-xs);
}

/* ============================================
   Footer
   ============================================ */
.site-footer {
    padding: var(--spacing-3xl) 0;
    margin-top: var(--spacing-3xl);
    border-top: 1px solid var(--color-border);
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: var(--spacing-xl);
    align-items: start;
}

.footer-contact strong {
    color: var(--color-text-secondary);
}

.footer-info {
    text-align: right;
}

.last-updated {
    margin-top: var(--spacing-xs);
    opacity: 0.7;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
    .profile-section {
        flex-direction: column;
        text-align: center;
    }

    .header-content {
        flex-direction: column;
        gap: var(--spacing-md);
        align-items: center;
    }

    .main-nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: var(--spacing-md);
    }

    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-info {
        text-align: center;
    }
}