/* ===== Variables ===== */
:root {
    --color-bg: #ffffff;
    --color-surface: #fafafa;
    --color-surface-alt: #f5f5f5;
    --color-text: #000000;
    --color-text-medium: #333333;
    --color-text-muted: #666666;
    --color-text-soft: #6e6e6e;
    --color-border: #e0e0e0;
    
    --font-serif: 'Fraunces', 'Iowan Old Style', 'Palatino Linotype', 'URW Palladio L', serif;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    --container: min(1000px, 90vw);
    --container-narrow: min(720px, 88vw);
    
    --space-2xs: 0.25rem;
    --space-xs: 0.5rem;
    --space-sm: 0.875rem;
    --space-md: 1.25rem;
    --space-lg: 2rem;
    --space-xl: 3.5rem;
    --space-2xl: 5rem;
    
    --radius-sm: 3px;
    --radius-md: 6px;
    --radius-lg: 12px;
    
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.08);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
    scroll-padding-top: 5rem;
}

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.65;
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ===== Utilities ===== */
.container {
    max-width: var(--container);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.container-narrow {
    max-width: var(--container-narrow);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

/* ===== Hero ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-2xl) var(--space-lg);
    background: var(--color-bg);
    position: relative;
    overflow: hidden;
}

.hero-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.hero-container {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-statement {
    font-family: var(--font-serif);
    font-size: clamp(2.5rem, 7vw, 5.5rem);
    font-weight: 500;
    line-height: 1.15;
    color: var(--color-text);
    letter-spacing: -0.03em;
    margin-bottom: var(--space-xl);
    display: flex;
    flex-direction: column;
    gap: 0.2em;
}

.statement-line {
    display: block;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 1s ease forwards;
}

.statement-line:nth-child(1) {
    animation-delay: 0.3s;
}

.statement-line:nth-child(2) {
    animation-delay: 0.6s;
}

.statement-subtitle {
    font-weight: 300;
    font-size: clamp(1.8rem, 5vw, 3.8rem);
    color: var(--color-text-muted);
    font-style: italic;
}

.dynamic-word {
    display: inline-block;
    position: relative;
    transition: opacity 0.4s ease, transform 0.4s ease;
}

.dynamic-word-2 {
    font-style: italic;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.scroll-indicator {
    background: none;
    border: 0;
    padding: 0;
    font-family: inherit;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-xs);
    cursor: pointer;
    color: var(--color-text-muted);
    transition: color 0.3s ease, transform 0.3s ease;
    margin-top: var(--space-2xl);
    opacity: 0;
    animation: fadeIn 1s ease forwards 1.2s;
}

@keyframes fadeIn {
    to { opacity: 1; }
}

.scroll-indicator:hover {
    color: var(--color-text);
    transform: translateY(3px);
}

.scroll-text {
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    text-transform: uppercase;
}

.scroll-arrow {
    font-size: 1rem;
    animation: float 2.5s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(6px); }
}

/* ===== Sections ===== */
section:not(.hero) {
    padding: var(--space-2xl) 0;
}

.section-title {
    font-family: var(--font-serif);
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: var(--space-xl);
    letter-spacing: -0.025em;
    line-height: 1.15;
}

/* ===== About ===== */
.about {
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
}

.about-lead {
    font-family: var(--font-serif);
    font-size: clamp(1.2rem, 2.5vw, 1.5rem);
    font-weight: 400;
    line-height: 1.55;
    color: var(--color-text-medium);
    max-width: 680px;
    margin-bottom: var(--space-lg);
}

.about-body {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    max-width: 680px;
    margin-bottom: var(--space-xl);
    line-height: 1.7;
}

.expertise-areas {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: var(--space-lg);
    max-width: 880px;
}

.expertise-item {
    padding: var(--space-lg) var(--space-md);
    background: var(--color-bg);
    border: 2px solid var(--color-text);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.expertise-item:hover {
    transform: translateY(-2px);
    box-shadow: 8px 8px 0 var(--color-text);
}

.expertise-label {
    display: block;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--color-text);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: var(--space-sm);
}

.expertise-item p {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.6;
}

/* ===== Experience ===== */
.experience {
    background: var(--color-bg);
}

.timeline {
    max-width: 840px;
    position: relative;
    padding-top: var(--space-lg);
    padding-left: 180px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 180px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, 
        var(--color-text) 0%, 
        var(--color-text) 50%, 
        var(--color-text-soft) 100%);
}

.timeline-item {
    position: relative;
    padding-left: 60px;
    margin-bottom: var(--space-2xl);
    opacity: 1;
}

.timeline-date {
    position: absolute;
    left: -180px;
    top: 0.15em;
    font-family: var(--font-sans);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-text-muted);
    letter-spacing: -0.01em;
    text-align: right;
    width: 140px;
    padding-right: var(--space-md);
    line-height: 1.3;
    opacity: 0;
    transform: translateX(-15px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.timeline-item.in-view .timeline-date {
    opacity: 1;
    transform: translateX(0);
}

.timeline-marker {
    position: absolute;
    left: -10px;
    top: 0.4em;
    width: 20px;
    height: 20px;
    background: var(--color-bg);
    border: 4px solid var(--color-text);
    border-radius: 50%;
    z-index: 2;
    box-shadow: 0 0 0 4px var(--color-bg);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.timeline-item:hover .timeline-marker {
    transform: scale(1.2);
}

.timeline-item.current .timeline-marker {
    background: var(--color-text);
    border-color: var(--color-text);
    box-shadow: 0 0 0 4px var(--color-bg), 0 0 0 8px var(--color-text);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        box-shadow: 0 0 0 4px var(--color-bg), 0 0 0 8px var(--color-text);
    }
    50% {
        box-shadow: 0 0 0 4px var(--color-bg), 0 0 0 12px rgba(0, 0, 0, 0.3);
    }
}

.timeline-content h3 {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: var(--space-2xs);
    letter-spacing: -0.02em;
    line-height: 1.3;
}

.timeline-company {
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-text-medium);
    margin-bottom: var(--space-sm);
}

.timeline-content p:not(.timeline-company) {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.65;
    margin-bottom: var(--space-sm);
}

.achievement {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-text);
    background: transparent;
    padding: 0.3rem 0.75rem;
    border-radius: 999px;
    letter-spacing: 0.03em;
    border: 1.5px solid var(--color-text);
}

/* ===== Research / Innovation ===== */
.research {
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
}

.research-intro {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    max-width: 680px;
    margin-bottom: var(--space-xl);
    line-height: 1.7;
}

.research-areas {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--space-lg);
    margin-bottom: var(--space-xl);
    max-width: 880px;
}

.research-area {
    padding: var(--space-lg);
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.research-area:hover {
    border-color: var(--color-text);
    box-shadow: var(--shadow-md);
}

.research-area h3 {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: var(--space-md);
    letter-spacing: -0.01em;
}

.research-area ul {
    list-style: none;
}

.research-area li {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    padding-left: 1.1rem;
    margin-bottom: 0.5rem;
    position: relative;
    line-height: 1.5;
}

.research-area li::before {
    content: '·';
    position: absolute;
    left: 0.3rem;
    color: var(--color-text);
    font-weight: 700;
    font-size: 1.2rem;
}

.research-cta {
    text-align: left;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.75rem 1.5rem;
    font-family: var(--font-sans);
    font-size: 0.9rem;
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--radius-sm);
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, transform 0.3s ease;
    cursor: pointer;
    letter-spacing: 0.015em;
}

.btn-outline {
    border: 1.5px solid var(--color-text);
    color: var(--color-text);
    background: var(--color-bg);
}

.btn-outline:hover {
    background: var(--color-text);
    color: var(--color-bg);
    transform: translateY(-2px);
}

/* ===== Contact ===== */
.contact {
    background: var(--color-bg);
    border-top: 1px solid var(--color-border);
}

.contact-card {
    max-width: 560px;
    padding: var(--space-xl) var(--space-lg);
    background: var(--color-surface);
    border: 2px solid var(--color-text);
    text-align: center;
}

.contact-text {
    font-size: 1.05rem;
    color: var(--color-text-muted);
    margin-bottom: var(--space-lg);
    line-height: 1.7;
}

.linkedin-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.9rem 2rem;
    background: var(--color-text);
    color: var(--color-bg);
    text-decoration: none;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    transition: background-color 0.3s ease, color 0.3s ease, transform 0.3s ease;
    letter-spacing: 0.015em;
    border: 2px solid var(--color-text);
}

.linkedin-btn:hover {
    background: var(--color-bg);
    color: var(--color-text);
    transform: translateY(-2px);
}

.linkedin-btn i {
    font-size: 1.1rem;
}

/* ===== Footer ===== */
.footer {
    padding: var(--space-xl) 0;
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-text {
    font-size: 0.85rem;
    color: var(--color-text-soft);
    letter-spacing: 0.02em;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    :root {
        --space-xl: 2.5rem;
        --space-2xl: 3.5rem;
    }

    .hero {
        padding: var(--space-xl) var(--space-md);
    }

    .hero-statement {
        margin-bottom: var(--space-lg);
    }

    .expertise-areas {
        grid-template-columns: 1fr;
    }

    .research-areas {
        grid-template-columns: 1fr;
    }

    .timeline {
        padding-left: 130px;
    }

    .timeline::before {
        left: 130px;
        width: 2px;
    }

    .timeline-item {
        padding-left: 44px;
        margin-bottom: var(--space-xl);
    }

    .timeline-date {
        left: -130px;
        width: 105px;
        padding-right: var(--space-sm);
        font-size: 0.95rem;
    }

    .timeline-marker {
        left: -8px;
        width: 16px;
        height: 16px;
        border-width: 3px;
    }

    .timeline-item.current .timeline-marker {
        box-shadow: 0 0 0 3px var(--color-bg), 0 0 0 6px var(--color-text);
    }

    @keyframes pulse {
        0%, 100% {
            box-shadow: 0 0 0 3px var(--color-bg), 0 0 0 6px var(--color-text);
        }
        50% {
            box-shadow: 0 0 0 3px var(--color-bg), 0 0 0 9px rgba(0, 0, 0, 0.3);
        }
    }

    .contact-card {
        padding: var(--space-lg) var(--space-md);
    }
}

@media (max-width: 480px) {
    body {
        font-size: 1.125rem;
    }

    .container,
    .container-narrow {
        padding: 0 var(--space-md);
    }

    section:not(.hero) {
        padding: var(--space-xl) 0;
    }

    .hero-statement {
        margin-bottom: var(--space-md);
    }

    .statement-subtitle {
        font-size: clamp(1.4rem, 4vw, 2.5rem);
    }

    .scroll-indicator {
        margin-top: var(--space-xl);
    }

    .scroll-text {
        font-size: 0.75rem;
    }

    .section-title {
        font-size: clamp(1.9rem, 5.5vw, 2.5rem);
        margin-bottom: var(--space-lg);
    }

    .about-lead {
        font-size: clamp(1.3rem, 3.2vw, 1.65rem);
        margin-bottom: var(--space-md);
    }

    .about-body {
        font-size: 1.125rem;
        margin-bottom: var(--space-lg);
    }

    .expertise-item {
        padding: var(--space-md) var(--space-sm);
    }

    .expertise-label {
        font-size: 0.8rem;
    }

    .expertise-item p {
        font-size: 1.05rem;
    }

    .research-intro {
        font-size: 1.125rem;
        margin-bottom: var(--space-lg);
    }

    .research-area h4 {
        font-size: 1.1rem;
    }

    .research-area li {
        font-size: 1rem;
    }

    .timeline {
        padding-left: 100px;
    }

    .timeline::before {
        left: 100px;
        width: 2px;
    }

    .timeline-item {
        padding-left: 32px;
        margin-bottom: var(--space-lg);
    }

    .timeline-date {
        left: -100px;
        width: 80px;
        padding-right: var(--space-xs);
        font-size: 0.95rem;
        font-weight: 700;
    }

    .timeline-content h3 {
        font-size: 1.35rem;
    }

    .timeline-company {
        font-size: 1.05rem;
    }

    .timeline-content p:not(.timeline-company) {
        font-size: 1.05rem;
    }

    .achievement {
        font-size: 0.8rem;
    }

    .timeline-marker {
        left: -6px;
        width: 12px;
        height: 12px;
        border-width: 2.5px;
    }

    .timeline-item.current .timeline-marker {
        box-shadow: 0 0 0 2px var(--color-bg), 0 0 0 5px var(--color-text);
    }

    @keyframes pulse {
        0%, 100% {
            box-shadow: 0 0 0 2px var(--color-bg), 0 0 0 5px var(--color-text);
        }
        50% {
            box-shadow: 0 0 0 2px var(--color-bg), 0 0 0 8px rgba(0, 0, 0, 0.3);
        }
    }

    .contact-text {
        font-size: 1.15rem;
    }

    .linkedin-btn {
        font-size: 1.1rem;
        padding: 1.1rem 2.5rem;
    }

    .btn {
        font-size: 1rem;
        padding: 0.85rem 1.75rem;
    }

    .contact-card {
        padding: var(--space-lg) var(--space-md);
    }

    .footer-text {
        font-size: 0.9rem;
    }
}

/* ===== Skip link ===== */
.skip-link {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 100;
    padding: 0.75rem 1.25rem;
    background: var(--color-text);
    color: var(--color-bg);
    font-size: 0.9rem;
    font-weight: 600;
    text-decoration: none;
    transform: translateY(-120%);
    transition: transform 0.2s ease;
}

.skip-link:focus-visible {
    transform: translateY(0);
}

/* ===== Site nav ===== */
.site-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.88);
    -webkit-backdrop-filter: saturate(180%) blur(12px);
    backdrop-filter: saturate(180%) blur(12px);
    border-bottom: 1px solid transparent;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-100%);
    transition: opacity 0.35s ease, transform 0.35s ease, visibility 0.35s;
}

.site-nav.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
    border-bottom-color: var(--color-border);
}

.site-nav-inner {
    max-width: var(--container);
    margin: 0 auto;
    padding: 0.9rem var(--space-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-md);
}

.site-nav-name {
    font-family: var(--font-serif);
    font-size: 1.05rem;
    font-weight: 500;
    letter-spacing: -0.01em;
    color: var(--color-text);
    text-decoration: none;
    white-space: nowrap;
}

.site-nav-links {
    display: flex;
    gap: var(--space-md);
}

.site-nav-links a {
    position: relative;
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.09em;
    text-transform: uppercase;
    color: var(--color-text-muted);
    text-decoration: none;
    padding: 0.25rem 0;
    transition: color 0.25s ease;
}

.site-nav-links a::after {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 1.5px;
    background: var(--color-text);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.25s ease;
}

.site-nav-links a:hover,
.site-nav-links a.is-active {
    color: var(--color-text);
}

.site-nav-links a:hover::after,
.site-nav-links a.is-active::after {
    transform: scaleX(1);
}

@media (max-width: 620px) {
    .site-nav-name { display: none; }
    .site-nav-inner { justify-content: center; }
    .site-nav-links { gap: var(--space-sm); }
    .site-nav-links a { font-size: 0.7rem; letter-spacing: 0.06em; }
}

/* ===== Focus visibility ===== */
:focus-visible {
    outline: 2px solid var(--color-text);
    outline-offset: 3px;
}

.linkedin-btn:focus-visible {
    outline-offset: 4px;
}

/* ===== Reduced motion ===== */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }

    .statement-line,
    .scroll-indicator,
    .timeline-date {
        opacity: 1 !important;
        transform: none !important;
    }
}