/* ===== CSS Variables ===== */
:root {
    --primary-color: #1e3a8a;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --gradient-primary: linear-gradient(135deg, #1e3a8a 0%, #1e40af 100%);
    --gradient-secondary: linear-gradient(135deg, #374151 0%, #1f2937 100%);
    --gradient-accent: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    --text-primary: #111827;
    --text-secondary: #4b5563;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 2px 4px 0 rgb(0 0 0 / 0.06);
    --shadow-lg: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --shadow-colored: 0 4px 6px -1px rgba(30, 58, 138, 0.15);
    --transition: all 0.3s ease;
    --transition-fast: all 0.15s ease;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-primary);
    background: #ffffff;
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* ===== Navigation Bar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    box-shadow: 0 1px 0 0 rgba(0, 0, 0, 0.05);
    z-index: 1000;
    padding: 1rem 0;
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
}

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

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

.nav-menu a.active::after,
.nav-menu a:hover::after {
    width: 100%;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    transition: var(--transition);
}

/* ===== Hero Section ===== */
main {
    padding-top: 80px;
}

.hero {
    padding: 6rem 0;
    background: var(--bg-secondary);
    position: relative;
    overflow: hidden;
    border-bottom: 1px solid var(--border-color);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text h1 {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

.highlight {
    color: var(--primary-color);
    position: relative;
    display: inline-block;
}

.subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.bio {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 2rem;
}

.social-links {
    display: flex;
    gap: 1rem;
}

.social-links a {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: white;
    border-radius: 6px;
    color: var(--text-secondary);
    font-size: 1.25rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.social-links a:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.profile-placeholder {
    width: 280px;
    height: 280px;
    background: var(--bg-tertiary);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    position: relative;
    border: 2px solid var(--border-color);
}

.profile-placeholder i {
    font-size: 100px;
    color: var(--text-secondary);
}

.profile-img {
    width: 280px;
    height: 280px;
    border-radius: 12px;
    object-fit: cover;
    box-shadow: var(--shadow-md);
    border: 2px solid var(--border-color);
}

/* ===== Section Styles ===== */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background-color: var(--primary-color);
    border-radius: 2px;
}

/* ===== Research Interests ===== */
.research-interests {
    padding: 5rem 0;
    background-color: var(--bg-primary);
}

.interests-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.interest-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
    position: relative;
}

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

.icon-wrapper {
    width: 72px;
    height: 72px;
    margin: 0 auto 1.5rem;
    background: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.icon-wrapper i {
    font-size: 2rem;
    color: white;
}

.interest-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.interest-card p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ===== Teaching Preview ===== */
.teaching-preview {
    padding: 5rem 0;
    background-color: var(--bg-primary);
}

.course-highlight {
    background: white;
    padding: 2.5rem;
    border-radius: 12px;
    border: 2px solid var(--primary-color);
    margin-bottom: 3rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.course-highlight:hover {
    box-shadow: var(--shadow-lg);
}

.course-badge {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--gradient-primary);
    color: white;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.course-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.course-description {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.course-info {
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ===== Recent Work ===== */
.recent-work {
    padding: 5rem 0;
    background-color: var(--bg-secondary);
}

.work-preview {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin-bottom: 3rem;
}

.work-item {
    background: white;
    padding: 2rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--primary-color);
    transition: var(--transition);
}

.work-item:hover {
    box-shadow: var(--shadow-md);
}

.work-item h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.work-meta {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.work-item p {
    color: var(--text-secondary);
    line-height: 1.6;
}

.cta-container {
    text-align: center;
}

/* ===== Buttons ===== */
.btn-primary,
.btn-secondary {
    display: inline-block;
    padding: 0.875rem 2rem;
    font-weight: 600;
    border-radius: 8px;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    background: var(--secondary-color);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

/* ===== Publications Page ===== */
.page-header {
    padding: 4rem 0;
    background: var(--bg-secondary);
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.page-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.header-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.stats-bar {
    display: flex;
    justify-content: center;
    gap: 4rem;
    margin: 2rem 0;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.publications-list {
    padding: 4rem 0;
    background-color: var(--bg-primary);
}

.pub-item {
    display: flex;
    gap: 2rem;
    margin-bottom: 3rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid var(--border-color);
}

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

.pub-year {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    min-width: 80px;
}

.pub-content {
    flex: 1;
}

.pub-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
    line-height: 1.4;
}

.pub-authors {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.pub-venue {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-bottom: 1rem;
}

.pub-metrics {
    margin-bottom: 1rem;
}

.metric {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background-color: var(--bg-secondary);
    border-radius: 20px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-right: 0.5rem;
}

.pub-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.pub-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background-color: var(--bg-secondary);
    border-radius: 6px;
    color: var(--primary-color);
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
}

.pub-link:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

/* ===== Blog Page ===== */
.blog-content {
    padding: 4rem 0;
    background-color: var(--bg-primary);
}

.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.blog-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
    transition: var(--transition);
}

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

.blog-image {
    width: 100%;
    height: 200px;
    background: var(--primary-color);
    overflow: hidden;
    position: relative;
}

.blog-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.blog-placeholder i {
    font-size: 4rem;
    color: rgba(255, 255, 255, 0.9);
}

.blog-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem 0.5rem;
}

.blog-date {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.blog-tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    background: var(--primary-color);
    color: white;
    border-radius: 4px;
    font-weight: 500;
}

.blog-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    padding: 0 1.5rem;
    margin-bottom: 0.75rem;
    line-height: 1.4;
}

.blog-excerpt {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
    padding: 0 1.5rem 1.5rem;
}

.empty-state {
    text-align: center;
    padding: 3rem;
    background-color: var(--bg-secondary);
    border-radius: 12px;
}

.empty-state i {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.empty-state h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.empty-state p {
    font-size: 1rem;
    color: var(--text-secondary);
}

/* ===== Papers Page ===== */
.papers-section {
    padding: 4rem 0;
    background-color: var(--bg-primary);
}

.papers-stats {
    padding: 2rem 0 0 0;
    background-color: var(--bg-primary);
}

.stats-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.stats-card-header {
    padding: 1.25rem 1.5rem 0.5rem 1.5rem;
}

.stats-subtitle {
    color: var(--text-secondary);
}

.chart-wrap {
    position: relative;
    height: 320px;
    padding: 0.5rem 1rem 1.25rem 1rem;
}

.stats-badges {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 0.75rem;
}

.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.35rem 0.6rem;
    border-radius: 999px;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.badge i { color: var(--primary-color); }

.badge.success {
    background: rgba(16, 185, 129, 0.15);
    color: #065f46;
}

.badge.muted {
    background: #eef2f7;
}

.chart-caption {
    margin-top: 0.75rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.papers-layout {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2rem;
    align-items: start;
}

.papers-filters {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
}

.filter-group + .filter-group {
    margin-top: 1rem;
}

.filter-label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.filter-input {
    width: 100%;
    padding: 0.625rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    outline: none;
}

.filter-input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.filter-actions {
    margin-top: 1rem;
}

.filter-meta {
    margin-top: 0.75rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.tag-list {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.tag-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.35rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 999px;
    background: white;
    color: var(--text-secondary);
    font-size: 0.85rem;
    cursor: pointer;
}

.tag-chip.small {
    padding: 0.2rem 0.5rem;
    font-size: 0.8rem;
}

.tag-chip.active,
.tag-chip:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.papers-results {
    min-height: 400px;
}

.papers-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.paper-item {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem 1.25rem;
}

.paper-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.paper-meta {
    display: flex;
    gap: 0.75rem;
    align-items: center;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.paper-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-bottom: 0.5rem;
}

.paper-excerpt {
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.paper-actions {
    display: flex;
    gap: 0.5rem;
}

.paper-reader {
    position: sticky;
    top: 100px;
}

.reader-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.25rem;
}

.reader-placeholder {
    display: grid;
    place-items: center;
    color: var(--text-secondary);
    min-height: 260px;
    text-align: center;
    gap: 0.5rem;
}

.reader-placeholder i {
    font-size: 2rem;
    color: var(--primary-color);
}

.reader-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.reader-abstract {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 0.75rem;
}

.reader-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.reader-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* Pagination */
.pagination {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 1rem;
}

.page-btn {
    padding: 0.5rem 0.9rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: white;
    color: var(--text-primary);
    cursor: pointer;
}

.page-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.page-numbers {
    display: flex;
    gap: 0.25rem;
}

.page-number {
    min-width: 36px;
    padding: 0.45rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: white;
    color: var(--text-secondary);
    cursor: pointer;
}

.page-number.active,
.page-number:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.page-ellipsis {
    display: inline-flex;
    align-items: center;
    color: var(--text-secondary);
    padding: 0 0.35rem;
}

@media (max-width: 1200px) {
    .papers-layout {
        grid-template-columns: 260px 1fr;
    }
}

@media (max-width: 968px) {
    .papers-layout {
        grid-template-columns: 1fr;
    }
}

/* ===== Teaching Page ===== */
.teaching-section {
    padding: 4rem 0;
    background-color: var(--bg-primary);
}

.course-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    margin-bottom: 3rem;
    transition: var(--transition);
}

.course-card.featured {
    border: 2px solid var(--primary-color);
    box-shadow: var(--shadow-md);
}

.course-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: 2.5rem;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    border-bottom: 1px solid var(--border-color);
}

.course-badge.current {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.9;
    }
}

.course-number {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.course-name {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.course-role {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.course-icon {
    font-size: 4rem;
    color: var(--primary-color);
    opacity: 0.2;
}

.course-body {
    padding: 2.5rem;
}

.course-meta {
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.5rem 0;
    color: var(--text-secondary);
}

.meta-item i {
    color: var(--primary-color);
    font-size: 1.1rem;
    width: 20px;
    text-align: center;
}

.course-description h4 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 2rem 0 1rem 0;
}

.course-description h4:first-child {
    margin-top: 0;
}

.course-description p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 1rem;
}

.course-description ul {
    list-style-position: inside;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 1rem;
}

.course-description li {
    padding-left: 0.5rem;
}

.focus-areas {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.focus-item {
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.focus-item i {
    font-size: 2rem;
    color: var(--primary-color);
    min-width: 40px;
    text-align: center;
}

.focus-item strong {
    display: block;
    font-size: 1.1rem;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.focus-item p {
    color: var(--text-secondary);
    margin: 0;
    font-size: 0.95rem;
}

.tools-list {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 1rem;
}

.tools-list li {
    padding: 0.5rem 0;
}

.course-links {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.course-link-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    border-radius: 8px;
    font-weight: 600;
    transition: var(--transition);
    text-decoration: none;
}

.course-link-btn.primary {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

.course-link-btn.primary:hover {
    background: var(--secondary-color);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.course-link-btn.secondary {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.course-link-btn.secondary:hover {
    background: var(--primary-color);
    color: white;
}

.teaching-philosophy {
    background: var(--bg-secondary);
    padding: 3rem;
    border-radius: 12px;
    margin-top: 3rem;
}

.teaching-philosophy .section-title {
    text-align: left;
    margin-bottom: 2rem;
}

.teaching-philosophy .section-title::after {
    left: 0;
    transform: none;
}

.philosophy-content p {
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 1.5rem;
}

.philosophy-points {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-top: 2rem;
}

.philosophy-item {
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
    background: white;
    padding: 2rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

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

.philosophy-item i {
    font-size: 2rem;
    color: var(--primary-color);
    min-width: 40px;
    text-align: center;
}

.philosophy-item strong {
    display: block;
    font-size: 1.15rem;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.philosophy-item p {
    color: var(--text-secondary);
    margin: 0;
    line-height: 1.6;
}

/* ===== Footer ===== */
footer {
    background-color: var(--text-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

footer p {
    font-size: 0.95rem;
}

/* ===== Responsive Design ===== */
@media (max-width: 968px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-text h1 {
        font-size: 2.5rem;
    }

    .social-links {
        justify-content: center;
    }

    .profile-placeholder {
        width: 250px;
        height: 250px;
    }

    .profile-placeholder i {
        font-size: 100px;
    }

    .profile-img {
        width: 250px;
        height: 250px;
    }

    .pub-item {
        flex-direction: column;
        gap: 1rem;
    }

    .pub-year {
        min-width: auto;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 0 1.5rem;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

    .hero-text h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1.25rem;
    }

    .bio {
        font-size: 1rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .page-header h1 {
        font-size: 2rem;
    }

    .stats-bar {
        gap: 2rem;
    }

    .blog-grid {
        grid-template-columns: 1fr;
    }

    .interests-grid {
        grid-template-columns: 1fr;
    }

    .course-header {
        flex-direction: column;
        gap: 1.5rem;
    }

    .course-icon {
        font-size: 3rem;
        align-self: center;
    }

    .course-name {
        font-size: 1.5rem;
    }

    .course-links {
        flex-direction: column;
    }

    .course-link-btn {
        width: 100%;
        justify-content: center;
    }

    .focus-item {
        flex-direction: column;
        text-align: center;
    }

    .focus-item i {
        align-self: center;
    }

    .philosophy-item {
        flex-direction: column;
        text-align: center;
    }

    .philosophy-item i {
        align-self: center;
    }

    .teaching-philosophy {
        padding: 2rem;
    }
}

@media (max-width: 480px) {
    .hero-text h1 {
        font-size: 1.75rem;
    }

    .stats-bar {
        flex-direction: column;
        gap: 1.5rem;
    }

    .profile-placeholder {
        width: 200px;
        height: 200px;
    }

    .profile-placeholder i {
        font-size: 80px;
    }

    .profile-img {
        width: 200px;
        height: 200px;
    }
}

/* ===== Animations ===== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.hero-content,
.interest-card,
.work-item,
.pub-item,
.blog-card {
    animation: fadeIn 0.4s ease-out;
}