/* ========================================
   CSS Variables
   ======================================== */

:root {
    /* Light Mode Colors */
    --bg-primary: #f8f9fb;
    --bg-secondary: rgba(248, 249, 251, 0.95);
    --text-primary: #1a1a1a;
    --text-secondary: #4a5568;
    --accent: #5b7c99;
    --accent-hover: #4a6278;
    --border: #e5e7eb;
    --shadow: rgba(0, 0, 0, 0.05);
    --badge-bg: #e8f0f7;
    --badge-text: #2c5282;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;

    /* Transitions */
    --transition-speed: 0.3s;
}

[data-theme="dark"] {
    /* Dark Mode Colors */
    --bg-primary: #0a0e1a;
    --bg-secondary: rgba(10, 14, 26, 0.95);
    --text-primary: #e5e7eb;
    --text-secondary: #9ca3af;
    --accent: #7da3c6;
    --accent-hover: #93b5d6;
    --border: #1f2937;
    --shadow: rgba(0, 0, 0, 0.3);
    --badge-bg: #1a2942;
    --badge-text: #93b5d6;
}

/* ========================================
   Reset & Base Styles
   ======================================== */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    font-size: 1.0625rem;
    font-weight: 400;
    line-height: 1.7;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

h1 {
    font-size: 2.5rem;
    font-weight: 600;
}

h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

h3 {
    font-size: 1.5rem;
    font-weight: 500;
    margin-top: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

h4 {
    font-size: 1.25rem;
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
    font-size: 1.0625rem;
    line-height: 1.7;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

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

ul {
    margin-left: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

li {
    margin-bottom: var(--spacing-xs);
    color: var(--text-secondary);
    font-size: 1.0625rem;
    line-height: 1.7;
}

blockquote {
    margin: var(--spacing-sm) 0;
    padding: var(--spacing-sm);
    border-left: 3px solid var(--accent);
    background-color: var(--bg-secondary);
    font-style: italic;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

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

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section {
    padding: var(--spacing-lg) 0;
    min-height: auto;
}

.section h2:first-child {
    margin-top: var(--spacing-lg);
}

.section h2 {
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
}

.section > .container > .course-card,
.section > .container > .course-level {
    margin-left: var(--spacing-md);
}

.section > .container > h3.course-level {
    margin-left: var(--spacing-md);
}

.section > .container > p {
    margin-left: var(--spacing-md);
}

.landing-section {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: calc(100vh - 60px);
    padding: var(--spacing-lg) 0;
}

/* ========================================
   Header & Navigation
   ======================================== */

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    backdrop-filter: blur(10px);
    z-index: 1000;
    transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.site-name {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

.site-name:hover {
    color: var(--accent);
    text-decoration: none;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.nav-tabs {
    display: flex;
    gap: var(--spacing-md);
}

.nav-tab {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    padding: var(--spacing-xs) 0;
    border-bottom: 2px solid transparent;
    transition: color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.nav-tab:hover {
    color: var(--accent);
    text-decoration: none;
}

.nav-tab.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 8px;
    width: 40px;
    height: 40px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

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

.theme-icon {
    font-size: 1.25rem;
}

/* ========================================
   Landing Section
   ======================================== */

.landing-content {
    display: flex;
    gap: var(--spacing-lg);
    align-items: flex-start;
    width: 100%;
}

.profile-photo-landing {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    border: 3px solid var(--border);
    transition: border-color var(--transition-speed) ease;
    flex-shrink: 0;
}

.landing-text {
    flex: 1;
}

.landing-title {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.landing-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.landing-affiliation {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.job-market-badge {
    display: inline-block;
    background-color: var(--badge-bg);
    color: var(--badge-text);
    padding: 0.4rem 0.8rem;
    border-radius: 6px;
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: var(--spacing-md);
}

.landing-links {
    font-size: 0.95rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

.landing-links a {
    margin: 0 0.25rem;
}

.landing-bio {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.research-interests {
    font-size: 0.95rem;
    margin-top: var(--spacing-md);
    color: var(--text-secondary);
}

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

.home-content {
    display: flex;
    gap: var(--spacing-lg);
    align-items: flex-start;
    margin-top: var(--spacing-md);
}

.profile-photo-home {
    width: 250px;
    height: 250px;
    border-radius: 8px;
    object-fit: cover;
    border: 1px solid var(--border);
    flex-shrink: 0;
}

.home-text {
    flex: 1;
}

.university-logo {
    margin-top: var(--spacing-lg);
    max-width: 90px;
    width: 100%;
    height: auto;
    opacity: 0.7;
    transition: opacity var(--transition-speed) ease;
    display: block;
}

.university-logo:hover {
    opacity: 1;
}

/* ========================================
   Research Page
   ======================================== */

.research-interests-list {
    list-style: none;
    margin-left: var(--spacing-md);
    margin-bottom: 0;
    padding-left: var(--spacing-md);
}

.research-interests-list li {
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    font-size: 1.0625rem;
    line-height: 1.7;
    font-weight: 400;
}

.research-interests-list li:before {
    content: "•";
    color: var(--accent);
    font-weight: bold;
    display: inline-block;
    width: 1em;
    margin-left: -1em;
}

.publication-entry,
.work-in-progress-entry {
    margin-left: var(--spacing-md);
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
    font-size: 1.0625rem;
    line-height: 1.7;
}

.paper-entry {
    margin-bottom: var(--spacing-lg);
}

.paper-abstract {
    margin-left: var(--spacing-lg);
    margin-top: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.7;
    text-align: justify;
}

.conference-entry {
    margin-left: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.conference-title {
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
    font-size: 1.0625rem;
    line-height: 1.7;
    font-style: italic;
}

.conference-list {
    list-style: none;
    margin-left: var(--spacing-md);
    padding-left: 0;
}

.conference-list li {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-size: 1.0625rem;
    line-height: 1.7;
    padding-left: 1em;
    text-indent: -1em;
}

/* ========================================
   Content Sections
   ======================================== */

.content {
    margin-top: var(--spacing-md);
}

.publication {
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border);
}

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

.pub-title {
    font-weight: 600;
    font-size: 1.125rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.pub-info {
    font-size: 0.95rem;
    margin-bottom: var(--spacing-xs);
}

.pub-abstract {
    font-size: 0.9rem;
    line-height: 1.6;
    color: var(--text-secondary);
    margin-top: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    text-align: justify;
}

.pub-links {
    font-size: 0.9rem;
}

.pub-links a {
    margin-right: var(--spacing-sm);
}

/* ========================================
   Teaching Page
   ======================================== */

.teaching-header {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin-bottom: var(--spacing-lg);
    border: 1px solid var(--border);
}

.teaching-rating {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.teaching-rating strong {
    color: var(--accent);
    font-size: 1.5rem;
}

.rmp-link {
    margin-bottom: var(--spacing-sm);
}

.rmp-link a {
    font-weight: 500;
}

.contact-info {
    margin-bottom: 0;
    font-size: 0.95rem;
}

.course-level {
    font-size: 1.75rem;
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    color: var(--accent);
    border-bottom: 2px solid var(--border);
    padding-bottom: var(--spacing-xs);
}

.course-card {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin-bottom: var(--spacing-md);
    border: 1px solid var(--border);
    transition: box-shadow var(--transition-speed) ease;
}

.course-card:hover {
    box-shadow: 0 4px 12px var(--shadow);
}

.course-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xs);
    gap: var(--spacing-md);
}

.course-title {
    font-weight: 600;
    font-size: 1.125rem;
    color: var(--text-primary);
    margin: 0;
    flex: 1;
}

.course-rating {
    background-color: var(--badge-bg);
    color: var(--badge-text);
    padding: 0.4rem 0.8rem;
    border-radius: 6px;
    font-weight: 600;
    font-size: 1rem;
    white-space: nowrap;
}

.course-semester {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.course-years {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.course-list {
    list-style: none;
    margin-left: 0;
    margin-bottom: 0;
    padding-left: var(--spacing-md);
}

.course-list li {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-size: 1.0625rem;
    line-height: 1.7;
}

.course-list li:before {
    content: "•";
    color: var(--accent);
    font-weight: bold;
    display: inline-block;
    width: 1em;
    margin-left: -1em;
}

.student-comments {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border);
}

.comment-label {
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.comment-indent {
    margin-left: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-style: italic;
    line-height: 1.6;
}

.student-comments blockquote {
    margin: var(--spacing-xs) 0;
    padding: var(--spacing-sm);
    border-left: 3px solid var(--accent);
    background-color: transparent;
    font-size: 0.9rem;
}

.teaching-philosophy {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin-bottom: var(--spacing-lg);
    border: 1px solid var(--border);
}

.teaching-philosophy h2 {
    margin-top: 0;
    margin-bottom: var(--spacing-md);
}

.teaching-philosophy p {
    margin-bottom: var(--spacing-md);
    line-height: 1.7;
}

.teaching-philosophy p:last-child {
    margin-bottom: 0;
    font-size: 0.95rem;
}

.teaching-interests-text {
    font-weight: 400;
    color: var(--text-primary);
    font-size: 1.0625rem;
    line-height: 1.7;
}

/* ========================================
   Contact Page
   ======================================== */

.contact-content {
    max-width: 700px;
    margin: var(--spacing-xl) auto;
    padding-top: var(--spacing-lg);
}

.contact-content p,
.contact-content ul {
    margin-left: 0;
}

/* ========================================
   CV Page
   ======================================== */

.cv-embed {
    margin-top: var(--spacing-md);
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
}

.cv-embed iframe {
    display: block;
    width: 100%;
    min-height: 800px;
}

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

.footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: var(--spacing-md) 0;
    text-align: center;
    transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.footer p {
    margin-bottom: var(--spacing-xs);
    font-size: 0.9rem;
}

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

@media (max-width: 768px) {
    * {
        max-width: 100vw;
    }

    html, body {
        overflow-x: hidden;
        width: 100%;
        position: relative;
    }

    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.75rem;
    }

    h3 {
        font-size: 1.25rem;
    }

    img {
        max-width: 100%;
        height: auto;
    }

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

    .landing-text {
        width: 100%;
    }

    .profile-photo-landing {
        width: 160px;
        height: 160px;
    }

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

    .landing-subtitle {
        font-size: 1.125rem;
    }

    .landing-affiliation {
        font-size: 0.95rem;
    }

    .nav-container {
        flex-direction: column;
        height: auto;
        padding: var(--spacing-sm) var(--spacing-md);
        gap: var(--spacing-sm);
    }

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

    .nav-right {
        width: 100%;
        justify-content: flex-start;
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }

    .nav-tab {
        font-size: 0.85rem;
    }

    .theme-toggle {
        margin-left: auto;
    }

    .section {
        padding: calc(60px + var(--spacing-md)) 0 var(--spacing-md);
        overflow-x: hidden;
        width: 100%;
    }

    .container {
        max-width: 100%;
        width: 100%;
        overflow-x: hidden;
        padding-left: var(--spacing-sm);
        padding-right: var(--spacing-sm);
    }

    .landing-section {
        min-height: auto;
        padding: calc(60px + var(--spacing-md)) var(--spacing-sm) var(--spacing-md);
    }

    .container {
        padding: 0 var(--spacing-sm);
    }

    .course-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-xs);
    }

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

@media (max-width: 480px) {
    body {
        font-size: 1rem;
    }

    .container {
        padding: 0 1rem;
    }

    .landing-title {
        font-size: 1.75rem;
    }

    .landing-subtitle {
        font-size: 1rem;
    }

    .profile-photo-landing {
        width: 140px;
        height: 140px;
    }

    .theme-toggle {
        width: 36px;
        height: 36px;
    }

    .theme-icon {
        font-size: 1rem;
    }

    .job-market-badge {
        font-size: 0.85rem;
        padding: 0.3rem 0.6rem;
    }

    .course-card {
        padding: var(--spacing-sm);
        margin-left: 0;
    }

    .home-content {
        flex-direction: column;
        align-items: center;
        gap: var(--spacing-sm);
        width: 100%;
    }

    .profile-photo-home {
        width: 150px;
        height: 150px;
        object-fit: cover;
        border-radius: 4px;
    }

    .home-text {
        width: 100%;
    }

    .section h2:first-child {
        margin-top: var(--spacing-sm);
    }

    .section h2 {
        margin-top: var(--spacing-md);
    }

    h2 {
        font-size: 1.25rem;
    }

    .section > .container > .course-card,
    .section > .container > .course-level,
    .section > .container > p {
        margin-left: 0;
    }

    .publication-entry,
    .work-in-progress-entry {
        margin-left: 0;
    }

    .paper-abstract {
        margin-left: var(--spacing-sm);
    }
}

/* Comprehensive Mobile Fix - Override all previous mobile styles */
@media (max-width: 767px) {
    body {
        font-size: 0.95rem !important;
        line-height: 1.6 !important;
    }

    h1 {
        font-size: 1.5rem !important;
    }

    h2 {
        font-size: 1.25rem !important;
        margin-top: 1.5rem !important;
        margin-bottom: 0.75rem !important;
    }

    h3 {
        font-size: 1.1rem !important;
    }

    h4 {
        font-size: 1rem !important;
    }

    p {
        font-size: 0.95rem !important;
        margin-bottom: 0.75rem !important;
    }

    .section {
        padding-top: 180px !important;
        padding-bottom: 1rem !important;
    }

    .landing-section {
        padding-top: 180px !important;
    }

    .container {
        padding: 0 0.75rem !important;
        max-width: 100% !important;
    }

    .section > .container > *,
    .publication-entry,
    .work-in-progress-entry,
    .course-card,
    .course-level,
    .research-interests-list,
    .paper-entry {
        margin-left: 0 !important;
    }

    .profile-photo-home {
        width: 110px !important;
        height: 110px !important;
        margin: 0 auto 1rem !important;
    }

    .home-content {
        gap: 0.75rem !important;
        padding-top: 1rem !important;
    }

    .section h2:first-of-type,
    .section > .container > *:first-child {
        margin-top: 1rem !important;
    }

    .university-logo {
        max-width: 90px !important;
        margin-top: 1rem !important;
    }

    .site-name {
        font-size: 1.15rem !important;
    }

    .nav-tab {
        font-size: 0.8rem !important;
    }

    .header {
        position: fixed !important;
        top: 0 !important;
        z-index: 9999 !important;
    }

    .nav-container {
        padding: 0.75rem 1rem !important;
    }

    .paper-abstract {
        margin-left: 0.5rem !important;
        padding-left: 0.5rem !important;
        font-size: 0.9rem !important;
    }

    .course-card {
        padding: 0.5rem !important;
        margin-bottom: 0.75rem !important;
    }

    .course-list,
    .research-interests-list {
        padding-left: 1.25rem !important;
        margin-left: 0 !important;
    }

    ul {
        margin-left: 1rem !important;
    }
}