/* ---------- Design tokens ---------- */
:root {
    --color-bg: #ffffff;
    --color-bg-alt: #f6f7f9;
    --color-surface: #ffffff;
    --color-text: #161a23;
    --color-text-muted: #565d6d;
    --color-border: #e4e7ec;
    --color-accent: #3452d6;
    --color-accent-strong: #24399f;
    --color-accent-contrast: #ffffff;
    --color-accent-2: #d6663a;
    --color-accent-rgb: 52, 82, 214;

    --font-sans: 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', ui-monospace, 'SFMono-Regular', Menlo, monospace;

    --container-width: 1120px;
    --radius-sm: 6px;
    --radius-md: 10px;
    --shadow-sm: 0 1px 2px rgba(16, 20, 30, 0.06);
    --shadow-md: 0 8px 24px rgba(16, 20, 30, 0.08);

    --space-1: 0.5rem;
    --space-2: 1rem;
    --space-3: 1.5rem;
    --space-4: 2rem;
    --space-5: 3rem;
    --space-6: 4.5rem;
    --space-7: 6rem;

    --header-height: 72px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #0c0e14;
        --color-bg-alt: #12151e;
        --color-surface: #151924;
        --color-text: #e7e9ef;
        --color-text-muted: #9aa1b2;
        --color-border: #262b3a;
        --color-accent: #7c94ff;
        --color-accent-strong: #a3b4ff;
        --color-accent-contrast: #0c0e14;
        --color-accent-2: #ff9166;
        --color-accent-rgb: 124, 148, 255;
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.35);
    }
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    margin: 0;
    font-family: var(--font-sans);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}
img, svg { display: block; max-width: 100%; }
ul, ol { list-style: none; margin: 0; padding: 0; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4, p { margin: 0; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }

:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
    border-radius: 2px;
}

@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;
    }
}

/* ---------- Layout helpers ---------- */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--space-3);
}

.section {
    padding: var(--space-6) 0;
    scroll-margin-top: var(--header-height);
}

.section-alt { background: var(--color-bg-alt); }

.section-header { max-width: 640px; margin-bottom: var(--space-5); }

.section-header h2 {
    font-size: clamp(1.75rem, 1.4rem + 1.6vw, 2.5rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-top: var(--space-2);
}

.section-lead {
    margin-top: var(--space-2);
    color: var(--color-text-muted);
    font-size: 1.05rem;
}

.eyebrow {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-accent);
    margin: 0;
}
.eyebrow-index {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.6rem;
    height: 1.6rem;
    border: 1px solid var(--color-accent);
    border-radius: 50%;
    font-size: 0.7rem;
    color: var(--color-accent);
}
.eyebrow-rule {
    flex: 1 1 auto;
    height: 1px;
    max-width: 4rem;
    background: linear-gradient(90deg, var(--color-accent), transparent);
}

.skip-link {
    position: absolute;
    left: -9999px;
    top: 0;
    background: var(--color-accent);
    color: var(--color-accent-contrast);
    padding: 0.75rem 1.25rem;
    z-index: 1000;
    border-radius: 0 0 var(--radius-sm) 0;
}
.skip-link:focus {
    left: 0;
}

/* ---------- Buttons ---------- */
.btn {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    transition: transform 0.15s ease, background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease, box-shadow 0.15s ease;
    border: 1px solid transparent;
    overflow: hidden;
}
.btn:hover { transform: translateY(-2px); }

.btn-primary {
    background: linear-gradient(135deg, var(--color-accent), var(--color-accent-strong));
    color: var(--color-accent-contrast);
    box-shadow: 0 1px 2px rgba(var(--color-accent-rgb), 0.2);
}
.btn-primary:hover { box-shadow: 0 10px 24px -8px rgba(var(--color-accent-rgb), 0.55); }
.btn-primary::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(115deg, transparent 30%, rgba(255, 255, 255, 0.35) 50%, transparent 70%);
    transform: translateX(-120%);
    transition: transform 0.5s ease;
}
.btn-primary:hover::after { transform: translateX(120%); }

.btn-secondary {
    background: transparent;
    border-color: var(--color-border);
    color: var(--color-text);
}
.btn-secondary:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
    box-shadow: 0 6px 16px -10px rgba(var(--color-accent-rgb), 0.5);
}

.btn-ghost {
    background: transparent;
    color: var(--color-text-muted);
    text-decoration: underline;
    text-underline-offset: 3px;
    padding: 0.75rem 0.5rem;
}
.btn-ghost:hover { color: var(--color-accent); }

/* ---------- Header / Nav ---------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    transition: box-shadow 0.2s ease;
}
.site-header.is-scrolled {
    box-shadow: var(--shadow-sm);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
}

.logo {
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 1.15rem;
    letter-spacing: -0.01em;
}
.logo-accent { color: var(--color-accent); }

.nav-list {
    display: none;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text-muted);
    padding: 0.5rem 0.25rem;
    position: relative;
}
.nav-link:hover, .nav-link[aria-current="true"] {
    color: var(--color-text);
}
.nav-link[aria-current="true"]::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: -2px;
    height: 2px;
    background: var(--color-accent);
    border-radius: 2px;
}

.nav-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    padding: 0;
}
.nav-toggle-bar {
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-nav {
    border-top: 1px solid var(--color-border);
    background: var(--color-bg);
}
.mobile-nav ul {
    display: flex;
    flex-direction: column;
    padding: var(--space-2) var(--space-3);
    gap: var(--space-1);
}
.mobile-nav-link {
    display: block;
    padding: 0.6rem 0;
    font-size: 1.05rem;
    font-weight: 500;
}
.mobile-nav[hidden] { display: none; }

@media (min-width: 860px) {
    .nav-list {
        display: flex;
        gap: var(--space-4);
    }
    .nav-toggle { display: none; }
    .mobile-nav { display: none !important; }
}

/* ---------- Hero ---------- */
.hero {
    position: relative;
    padding: var(--space-7) 0 var(--space-6);
    overflow: hidden;
    background-image:
        radial-gradient(circle, var(--color-border) 1px, transparent 1px);
    background-size: 26px 26px;
    background-position: -13px -13px;
}
.hero::before {
    content: "";
    position: absolute;
    top: -10%;
    left: 50%;
    width: 60rem;
    height: 60rem;
    transform: translateX(-50%);
    background: radial-gradient(circle, rgba(var(--color-accent-rgb), 0.16), transparent 65%);
    pointer-events: none;
    z-index: 0;
}
.hero::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, transparent 60%, var(--color-bg) 100%);
    pointer-events: none;
    z-index: 0;
}
.hero-inner { position: relative; z-index: 1; max-width: 720px; }

.hero-title {
    font-size: clamp(2.5rem, 1.9rem + 3vw, 4rem);
    font-weight: 800;
    letter-spacing: -0.03em;
    margin-top: var(--space-2);
    line-height: 1.05;
    background: linear-gradient(100deg, var(--color-text) 40%, var(--color-accent) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.scroll-cue {
    position: relative;
    z-index: 1;
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-top: var(--space-6);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-text-muted);
}
.scroll-cue-line {
    width: 1px;
    height: 28px;
    background: linear-gradient(180deg, var(--color-accent), transparent);
    animation: scrollCue 1.8s ease-in-out infinite;
}
@keyframes scrollCue {
    0%, 100% { transform: scaleY(0.6); opacity: 0.5; }
    50% { transform: scaleY(1); opacity: 1; }
}

.hero-subtitle {
    font-size: clamp(1.1rem, 1rem + 0.5vw, 1.4rem);
    font-weight: 500;
    color: var(--color-text);
    margin-top: var(--space-3);
}

.hero-description {
    margin-top: var(--space-2);
    color: var(--color-text-muted);
    font-size: 1.05rem;
    max-width: 60ch;
}

.availability-badge {
    position: relative;
    z-index: 1;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: var(--space-3);
    padding: 0.4rem 0.8rem;
    border: 1px solid var(--color-border);
    border-radius: 999px;
    background: var(--color-surface);
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--color-text-muted);
}
.availability-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #29b06d;
    box-shadow: 0 0 0 3px rgba(41, 176, 109, 0.2);
}

.hero-actions {
    position: relative;
    z-index: 1;
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    margin-top: var(--space-4);
}

.hero-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-3);
    margin-top: var(--space-5);
}

.icon-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-muted);
}
.icon-link:hover { color: var(--color-accent); }
.icon-link svg { width: 18px; height: 18px; }

/* ---------- Tech ticker ---------- */
.ticker {
    position: relative;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg-alt);
    overflow: hidden;
    padding: 0.9rem 0;
}
.ticker-track {
    display: flex;
    width: max-content;
    gap: 3rem;
    animation: tickerScroll 32s linear infinite;
}
.ticker-item {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-text-muted);
    white-space: nowrap;
}
.ticker-item::before {
    content: "//";
    color: var(--color-accent);
}
@keyframes tickerScroll {
    from { transform: translateX(0); }
    to { transform: translateX(-50%); }
}
@media (prefers-reduced-motion: reduce) {
    .ticker-track {
        animation: none;
        flex-wrap: wrap;
        transform: none;
        width: auto;
    }
    .ticker { overflow: visible; }
}

/* ---------- About ---------- */
.about-grid {
    display: grid;
    gap: var(--space-4);
}
.about-copy p { margin-bottom: var(--space-2); color: var(--color-text-muted); max-width: 68ch; }
.about-copy strong { color: var(--color-text); }

.about-facts {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    box-shadow: var(--shadow-sm);
    align-self: start;
}
.about-facts h3 { font-size: 1rem; margin-bottom: var(--space-2); }
.facts-list { display: flex; flex-direction: column; gap: var(--space-1); }
.facts-list li { display: flex; flex-direction: column; font-size: 0.95rem; padding: 0.4rem 0; border-bottom: 1px solid var(--color-border); }
.facts-list li:last-child { border-bottom: none; }
.facts-label { font-family: var(--font-mono); font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--color-text-muted); margin-bottom: 0.2rem; }

@media (min-width: 860px) {
    .about-grid { grid-template-columns: 1.4fr 1fr; align-items: start; }
}

/* ---------- Expertise ---------- */
.expertise-grid {
    display: grid;
    gap: var(--space-3);
    grid-template-columns: 1fr;
}
.expertise-card {
    position: relative;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    overflow: hidden;
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.expertise-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--color-accent), var(--color-accent-2));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.25s ease;
}
.expertise-card:hover {
    transform: translateY(-3px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-md);
}
.expertise-card:hover::before { transform: scaleX(1); }
.expertise-card h3 { font-size: 1.05rem; margin-bottom: var(--space-2); }
.expertise-card p { color: var(--color-text-muted); font-size: 0.95rem; }

.tag-list { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.tag {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    padding: 0.3rem 0.6rem;
    border-radius: var(--radius-sm);
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    color: var(--color-text-muted);
}

@media (min-width: 640px) {
    .expertise-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1000px) {
    .expertise-grid { grid-template-columns: repeat(3, 1fr); }
}

/* ---------- Experience timeline ---------- */
.timeline {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
    border-left: 2px solid var(--color-border);
    padding-left: var(--space-4);
}

.timeline-item {
    position: relative;
}
.timeline-item::before {
    content: "";
    position: absolute;
    left: calc(-1 * var(--space-4) - 5px);
    top: 1.6rem;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--color-bg);
    border: 2px solid var(--color-accent);
}
.timeline-item[data-end="present"]::before {
    background: var(--color-accent);
    box-shadow: 0 0 0 4px rgba(var(--color-accent-rgb), 0.18), 0 0 14px rgba(var(--color-accent-rgb), 0.55);
    animation: pulseMarker 2.4s ease-in-out infinite;
}
@keyframes pulseMarker {
    0%, 100% { box-shadow: 0 0 0 4px rgba(var(--color-accent-rgb), 0.18), 0 0 14px rgba(var(--color-accent-rgb), 0.55); }
    50% { box-shadow: 0 0 0 7px rgba(var(--color-accent-rgb), 0.1), 0 0 18px rgba(var(--color-accent-rgb), 0.7); }
}

.timeline-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.timeline-card:hover {
    transform: translateY(-3px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-md);
}

.timeline-head {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: var(--space-2);
    margin-bottom: var(--space-1);
}
.timeline-head h3 { font-size: 1.2rem; }
.timeline-org { color: var(--color-accent); font-weight: 600; margin-top: 0.15rem; }
.timeline-org-sub { color: var(--color-text-muted); font-size: 0.85rem; margin-top: 0.1rem; }

.timeline-meta {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    text-align: right;
    gap: 0.15rem;
}
.timeline-dates {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--color-text-muted);
}
.timeline-duration {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

.timeline-location, .timeline-project {
    color: var(--color-text-muted);
    font-size: 0.92rem;
    margin-bottom: var(--space-2);
}
.timeline-project { font-weight: 600; color: var(--color-text); }

.timeline-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: var(--space-3);
}
.timeline-list li {
    position: relative;
    padding-left: 1.1rem;
    color: var(--color-text-muted);
    font-size: 0.95rem;
}
.timeline-list li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0.55rem;
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--color-accent);
}

/* ---------- Capabilities ---------- */
.philosophy {
    margin: 0 0 var(--space-4);
    padding: var(--space-3) var(--space-4);
    border-left: 3px solid var(--color-accent);
    background: var(--color-surface);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    font-size: 1.05rem;
    font-style: normal;
    color: var(--color-text);
    max-width: 68ch;
}

.capability-grid {
    display: grid;
    gap: var(--space-3);
    grid-template-columns: 1fr;
}
.capability-item {
    position: relative;
    padding: var(--space-2) 0 var(--space-2) var(--space-2);
    border-bottom: 1px solid var(--color-border);
    border-left: 2px solid transparent;
    transition: border-color 0.2s ease, background-color 0.2s ease;
}
.capability-item:hover {
    border-left-color: var(--color-accent);
    background: var(--color-surface);
}
.capability-item h3 { font-size: 1rem; margin-bottom: 0.35rem; }
.capability-item p { color: var(--color-text-muted); font-size: 0.92rem; }

@media (min-width: 640px) {
    .capability-grid { grid-template-columns: repeat(2, 1fr); column-gap: var(--space-4); }
}

/* ---------- Education ---------- */
.education-grid {
    display: grid;
    gap: var(--space-3);
    grid-template-columns: 1fr;
}
.education-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-3);
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.education-card:hover {
    transform: translateY(-3px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-md);
}
.education-head {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 0.4rem;
}
.education-head h3 { font-size: 1.05rem; }
.education-dates {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--color-text-muted);
}
.education-org { color: var(--color-accent); font-weight: 600; font-size: 0.92rem; }

@media (min-width: 860px) {
    .education-grid { grid-template-columns: repeat(3, 1fr); }
}

/* ---------- Writing ---------- */
.writing-grid {
    display: grid;
    gap: var(--space-3);
    grid-template-columns: 1fr;
}
.writing-empty {
    border: 1px dashed var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-4);
    color: var(--color-text-muted);
    font-size: 0.95rem;
}
.writing-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-3);
}
.writing-card h3 { font-size: 1.05rem; margin-bottom: 0.4rem; }
.writing-card p { color: var(--color-text-muted); font-size: 0.92rem; }

/* ---------- Contact ---------- */
.contact-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    align-items: center;
}
.copy-message {
    margin-top: var(--space-2);
    font-size: 0.9rem;
    color: var(--color-accent);
    min-height: 1.2em;
}

/* ---------- Footer ---------- */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: var(--space-4) 0;
    color: var(--color-text-muted);
    font-size: 0.85rem;
    text-align: center;
}

/* ---------- Scroll reveal (progressive enhancement) ---------- */
.js-animations .reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
.js-animations .reveal.is-visible {
    opacity: 1;
    transform: none;
}

/* ---------- Back to top ---------- */
.back-to-top {
    position: fixed;
    right: var(--space-3);
    bottom: var(--space-3);
    z-index: 90;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
    color: var(--color-text);
    opacity: 0;
    transform: translateY(8px);
    transition: opacity 0.2s ease, transform 0.2s ease, border-color 0.2s ease, color 0.2s ease;
    pointer-events: none;
}
.back-to-top.is-visible {
    opacity: 1;
    transform: none;
    pointer-events: auto;
}
.back-to-top:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}
.back-to-top svg { width: 20px; height: 20px; }

/* ---------- Print ---------- */
@media print {
    .site-header, .mobile-nav, .nav-toggle, .ticker, .scroll-cue,
    .back-to-top, .skip-link, .hero-actions, .contact-actions,
    .copy-message, #copyEmailBtn {
        display: none !important;
    }
    .hero::before, .hero::after { display: none; }
    body { color: #000; background: #fff; }
    .hero-title { -webkit-text-fill-color: #000; color: #000; background: none; }
    a { color: #000; text-decoration: underline; }
    .section { padding: 1rem 0; }
    .expertise-card, .timeline-card, .education-card {
        box-shadow: none;
        border: 1px solid #ccc;
        break-inside: avoid;
    }
    .timeline { border-left-color: #ccc; }
}