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

:root {
    --color-bg: #0a0a0b;
    --color-bg-alt: #111113;
    --color-surface: #18181b;
    --color-surface-hover: #1f1f23;
    --color-border: #27272a;
    --color-border-light: #3f3f46;
    --color-text: #fafafa;
    --color-text-secondary: #a1a1aa;
    --color-text-muted: #71717a;
    --color-accent: #3b82f6;
    --color-accent-light: #60a5fa;
    --color-accent-glow: rgba(59, 130, 246, 0.15);
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    color: inherit;
    text-decoration: none;
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

/* ============================================
   LAYOUT
   ============================================ */
.container {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section {
    padding: 8rem 0;
    position: relative;
}

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

.section-header {
    margin-bottom: 4rem;
}

.section-tag {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--color-accent);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: 1.25rem;
}

.section-title {
    font-size: clamp(1.75rem, 4vw, 2.75rem);
    font-weight: 600;
    line-height: 1.2;
    color: var(--color-text);
    max-width: 640px;
}

/* ============================================
   NAVIGATION
   ============================================ */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    padding: 1.25rem 0;
    transition: all 0.4s var(--ease-out);
    background: transparent;
}

.nav.scrolled {
    background: rgba(10, 10, 11, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    padding: 0.75rem 0;
}

.nav-inner {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-family: var(--font-mono);
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
    letter-spacing: -0.02em;
    transition: color 0.3s;
}

.nav-logo:hover {
    color: var(--color-accent);
}

.nav-links {
    display: flex;
    gap: 2.5rem;
}

.nav-links a {
    font-size: 0.875rem;
    font-weight: 400;
    color: var(--color-text-secondary);
    transition: color 0.3s;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--color-accent);
    transition: width 0.3s var(--ease-out);
}

.nav-links a:hover {
    color: var(--color-text);
}

.nav-links a:hover::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: all 0.3s var(--ease-out);
}

/* ============================================
   HERO
   ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    padding: 6rem 2rem 4rem;
}

.hero-bg {
    position: absolute;
    inset: 0;
    z-index: 0;
}

.hero-grid {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(59, 130, 246, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(59, 130, 246, 0.03) 1px, transparent 1px);
    background-size: 64px 64px;
    mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black 20%, transparent 70%);
    -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black 20%, transparent 70%);
}

.hero-content {
    max-width: 1120px;
    margin: 0 auto;
    width: 100%;
    position: relative;
    z-index: 1;
}

.hero-tag {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--color-accent);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: 1.5rem;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeUp 0.8s var(--ease-out) 0.2s forwards;
}

.hero-title {
    font-size: clamp(2.5rem, 7vw, 5rem);
    font-weight: 700;
    line-height: 1.08;
    letter-spacing: -0.03em;
    margin-bottom: 1.75rem;
}

.hero-line {
    display: block;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeUp 0.8s var(--ease-out) forwards;
}

.hero-line:nth-child(1) { animation-delay: 0.3s; }
.hero-line:nth-child(2) { animation-delay: 0.45s; }
.hero-line:nth-child(3) { animation-delay: 0.6s; }

.hero-line.accent {
    background: linear-gradient(135deg, var(--color-accent), var(--color-accent-light));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-sub {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
    max-width: 540px;
    line-height: 1.7;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeUp 0.8s var(--ease-out) 0.75s forwards;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    margin-top: 2.5rem;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeUp 0.8s var(--ease-out) 0.9s forwards;
}

.hero-social {
    display: flex;
    gap: 1rem;
    margin-top: 3rem;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeUp 0.8s var(--ease-out) 1.05s forwards;
}

.hero-social a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border-radius: 12px;
    border: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    transition: all 0.3s var(--ease-out);
}

.hero-social a:hover {
    color: var(--color-text);
    border-color: var(--color-accent);
    background: var(--color-accent-glow);
    transform: translateY(-2px);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    padding: 0.8rem 1.75rem;
    border-radius: 10px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s var(--ease-out);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--color-accent);
    color: #fff;
}

.btn-primary:hover {
    background: var(--color-accent-light);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(59, 130, 246, 0.3);
}

.btn-outline {
    border: 1px solid var(--color-border-light);
    color: var(--color-text-secondary);
    background: transparent;
}

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

/* Scroll indicator */
.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    opacity: 0;
    animation: fadeIn 1s var(--ease-out) 1.5s forwards;
}

.scroll-line {
    width: 1px;
    height: 48px;
    background: var(--color-border);
    position: relative;
    overflow: hidden;
}

.scroll-line::after {
    content: '';
    position: absolute;
    top: -100%;
    left: 0;
    width: 100%;
    height: 50%;
    background: var(--color-accent);
    animation: scrollDown 2s var(--ease-in-out) infinite;
}

/* ============================================
   ABOUT
   ============================================ */
.about-text {
    max-width: 680px;
}

.about-text p {
    color: var(--color-text-secondary);
    font-size: 1.05rem;
    line-height: 1.8;
    margin-bottom: 1.5rem;
}


/* ============================================
   EXPERTISE CARDS
   ============================================ */
.expertise-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: 2rem;
    transition: all 0.4s var(--ease-out);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--color-accent), transparent);
    opacity: 0;
    transition: opacity 0.4s;
}

.card:hover {
    border-color: var(--color-border-light);
    transform: translateY(-4px);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.card:hover::before {
    opacity: 1;
}

.card-icon {
    color: var(--color-accent);
    margin-bottom: 1.25rem;
}

.card-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--color-text);
}

.card-text {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 1.25rem;
}

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

.card-tags li {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    padding: 0.3rem 0.7rem;
    border-radius: 6px;
    background: rgba(59, 130, 246, 0.08);
    color: var(--color-accent-light);
    border: 1px solid rgba(59, 130, 246, 0.12);
}

/* ============================================
   AI SECTION
   ============================================ */
.ai-section {
    position: relative;
    overflow: hidden;
    background: var(--color-bg);
}

.ai-glow {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.ai-banner {
    text-align: center;
    max-width: 780px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.ai-banner .section-tag {
    background: linear-gradient(135deg, var(--color-accent), #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 0.85rem;
    letter-spacing: 0.15em;
}

.ai-headline {
    font-size: clamp(2rem, 5vw, 3.25rem);
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -0.03em;
    color: var(--color-text);
    margin: 1.25rem 0 1.75rem;
}

.ai-accent {
    background: linear-gradient(135deg, var(--color-accent), #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.ai-text {
    font-size: 1.1rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
    max-width: 640px;
    margin: 0 auto 3.5rem;
}

.ai-pillars {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    text-align: left;
}

.ai-pillar {
    padding: 1.75rem;
    border-radius: 16px;
    border: 1px solid var(--color-border);
    background: var(--color-surface);
    position: relative;
    overflow: hidden;
    transition: all 0.4s var(--ease-out);
}

.ai-pillar::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--color-accent), #a78bfa);
    opacity: 0.6;
}

.ai-pillar:hover {
    border-color: var(--color-border-light);
    transform: translateY(-4px);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.ai-pillar-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 0.5rem;
}

.ai-pillar p {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

/* ============================================
   TIMELINE
   ============================================ */
.timeline {
    position: relative;
    padding-left: 3rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 7px;
    top: 8px;
    bottom: 8px;
    width: 1px;
    background: var(--color-border);
}

.timeline-item {
    position: relative;
    padding-bottom: 3.5rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-marker {
    position: absolute;
    left: -3rem;
    top: 6px;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    border: 2px solid var(--color-border-light);
    background: var(--color-bg);
    z-index: 1;
    transition: all 0.3s;
}

.timeline-marker.active {
    border-color: var(--color-accent);
    background: var(--color-accent);
    box-shadow: 0 0 0 4px var(--color-accent-glow);
}

.timeline-date {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
    letter-spacing: 0.02em;
}

.timeline-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.35rem;
}

.timeline-company {
    font-size: 0.9rem;
    color: var(--color-accent);
    font-weight: 500;
    margin-bottom: 0.75rem;
}

.timeline-content p:last-child {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    line-height: 1.75;
    max-width: 600px;
}

/* ============================================
   EDUCATION
   ============================================ */
.education-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.edu-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: 2rem;
    transition: all 0.4s var(--ease-out);
}

.edu-card:hover {
    border-color: var(--color-border-light);
    transform: translateY(-4px);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.edu-degree {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 0.35rem;
}

.edu-school {
    font-size: 0.875rem;
    color: var(--color-accent);
    font-weight: 500;
    margin-bottom: 1rem;
}

.edu-detail {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 1.25rem;
}

.edu-highlights {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.edu-highlights span {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    padding: 0.3rem 0.7rem;
    border-radius: 6px;
    background: rgba(59, 130, 246, 0.08);
    color: var(--color-accent-light);
    border: 1px solid rgba(59, 130, 246, 0.12);
}

/* ============================================
   CONTACT
   ============================================ */
.contact-block {
    text-align: center;
    max-width: 560px;
    margin: 0 auto;
}

.contact-title {
    font-size: clamp(1.75rem, 4vw, 2.75rem);
    font-weight: 600;
    line-height: 1.2;
    margin: 1.25rem 0 1rem;
}

.contact-text {
    font-size: 1.05rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 2.5rem;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 1rem;
}

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.8rem 1.75rem;
    border-radius: 10px;
    border: 1px solid var(--color-border-light);
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s var(--ease-out);
}

.contact-link:hover {
    border-color: var(--color-accent);
    color: var(--color-text);
    background: var(--color-accent-glow);
    transform: translateY(-2px);
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    padding: 2rem 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer p {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* ============================================
   ANIMATIONS
   ============================================ */
@keyframes fadeUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

@keyframes scrollDown {
    0% { top: -100%; }
    100% { top: 200%; }
}

/* Scroll reveal base */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s var(--ease-out), transform 0.8s var(--ease-out);
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 1024px) {
    .expertise-grid,
    .education-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .ai-pillars {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .section {
        padding: 5rem 0;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        background: rgba(10, 10, 11, 0.95);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        border-bottom: 1px solid var(--color-border);
        padding: 1.5rem 2rem;
        gap: 1.25rem;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.open span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.open span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.open span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

.expertise-grid,
    .education-grid,
    .ai-pillars {
        grid-template-columns: 1fr;
    }

    .hero {
        padding: 5rem 1.5rem 3rem;
    }

    .hero-cta {
        flex-direction: column;
    }

    .btn {
        text-align: center;
        justify-content: center;
    }

    .contact-links {
        flex-direction: column;
        align-items: center;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2.25rem;
    }

    .container {
        padding: 0 1.25rem;
    }

    .card,
    .edu-card {
        padding: 1.5rem;
    }
}