:root {
    --bg-color: #FAFAFA;
    --text-color: #1A1A1A;
    --text-muted: #5F6368;
    --accent-color: #E64A19;
    /* Professional, high-contrast Orange-Red */
    --accent-glow: rgba(230, 74, 25, 0.08);
    --border-color: #E0E0E0;
    --card-bg: #FFFFFF;
    --card-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --max-width: 960px;
    --section-spacing: 7rem;
    /* Reasonable breathing room */
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #121212;
        --text-color: #E8EAED;
        --text-muted: #9AA0A6;
        --accent-color: #FF5722;
        --accent-glow: rgba(255, 87, 34, 0.1);
        --border-color: #2D2D2D;
        --card-bg: #1E1E1E;
        --card-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
    }
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    color: inherit;
    text-decoration: none;
    transition: all 0.2s ease;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* Header & Nav */
header.site-header {
    position: sticky;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(var(--bg-color-rgb, 250, 250, 250), 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    padding: 1.25rem 0;
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.3s ease;
}

@media (prefers-color-scheme: dark) {
    header.site-header {
        background: rgba(18, 18, 18, 0.95);
    }
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.1rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    gap: 1.75rem;
    align-items: center;
}

.nav-links a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-muted);
}

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

.nav-links .ai-nav-btn {
    color: var(--accent-color);
    font-weight: 600;
}

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

/* Burger Menu */
.burger {
    display: none;
    cursor: pointer;
    z-index: 1100;
}

.burger div {
    width: 22px;
    height: 2px;
    background-color: var(--text-color);
    margin: 5px;
    transition: all 0.3s ease;
}

@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 0;
        right: 0;
        height: 100vh;
        width: 100%;
        background: var(--bg-color);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 2.5rem;
        transform: translateX(100%);
        transition: transform 0.4s ease;
        z-index: 1050;
    }

    .nav-links.active {
        transform: translateX(0);
    }

    .nav-links a {
        font-size: 1.25rem;
    }

    .burger {
        display: block;
    }

    .burger.toggle .line1 {
        transform: rotate(-45deg) translate(-5px, 5px);
    }

    .burger.toggle .line2 {
        opacity: 0;
    }

    .burger.toggle .line3 {
        transform: rotate(45deg) translate(-5px, -5px);
    }
}

/* Hero Section */
.hero {
    padding: 8rem 0 4rem;
}

.hero h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    line-height: 1.2;
    font-weight: 800;
    letter-spacing: -0.04em;
    margin-bottom: 1.5rem;
}

.hero h1 span {
    color: var(--accent-color);
}

.hero p {
    font-size: 1.15rem;
    color: var(--text-muted);
    max-width: 650px;
    margin-bottom: 2.5rem;
}

.hero-wrapper {
    display: flex;
    align-items: center;
    gap: 4rem;
    flex-wrap: wrap-reverse;
}

.hero-content {
    flex: 1;
    min-width: 320px;
}

.hero-btn-container {
    display: flex;
    gap: 1rem;
}

.hero-image {
    flex-shrink: 0;
}

.hero-image img {
    width: 250px;
    height: 250px;
    border-radius: 20px;
    object-fit: cover;
    border: 1px solid var(--border-color);
    box-shadow: var(--card-shadow);
}

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

    .hero-wrapper {
        gap: 2rem;
        flex-direction: column-reverse;
        align-items: center;
        text-align: center;
    }

    .hero-btn-container {
        justify-content: center;
    }

    .hero-image {
        margin-bottom: 0.5rem;
    }

    .hero-image img {
        width: 180px;
        height: 180px;
        border-radius: 50%;
    }
}

/* Reveal Animation */
.reveal {
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.7s ease-out;
}

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

/* Section Common */
section {
    padding: calc(var(--section-spacing) / 2) 0;
}

h2 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--accent-color);
    /* Prominent contrast */
    margin-bottom: 2.5rem;
    font-weight: 700;
}

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

.expertise-card {
    padding: 2rem;
    border: 1px solid var(--border-color);
    border-radius: 16px;
    background: var(--card-bg);
    box-shadow: var(--card-shadow);
    transition: transform 0.2s ease, border-color 0.2s ease;
}

.expertise-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent-color);
}

.expertise-card h4 {
    font-size: 1.1rem;
    margin-bottom: 0.75rem;
    font-weight: 700;
}

.expertise-card p {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 1.5rem;
}

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

.tag {
    font-size: 0.8rem;
    padding: 0.3rem 0.75rem;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-color);
    font-weight: 500;
}

/* Timeline */
.timeline-item {
    display: grid;
    grid-template-columns: 220px 1fr;
    gap: 2rem;
    margin-bottom: 3rem;
}

.time-header h3 {
    font-size: 1.15rem;
    font-weight: 700;
}

.time-content .position {
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-color);
    font-size: 1.05rem;
}

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

@media (max-width: 600px) {
    .timeline-item {
        grid-template-columns: 1fr;
        gap: 0.5rem;
    }
}

/* Recommendations Carousel */
.recommendations-wrapper {
    position: relative;
    width: 100%;
}

.recommendations-carousel {
    display: flex;
    overflow-x: auto;
    scroll-snap-type: x mandatory;
    gap: 1.5rem;
    padding-bottom: 1rem;
    scrollbar-width: none;
    /* Firefox */
    -ms-overflow-style: none;
    /* IE/Edge */
}

.recommendations-carousel::-webkit-scrollbar {
    display: none;
    /* Chrome/Safari */
}

.rec-card {
    min-width: 340px;
    max-width: 340px;
    scroll-snap-align: start;
    padding: 2.5rem;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    box-shadow: var(--card-shadow);
    display: flex;
    flex-direction: column;
}

@media (max-width: 500px) {
    .rec-card {
        min-width: 85vw;
        max-width: 85vw;
    }
}

.nav-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: 1px solid var(--border-color);
    background: transparent;
    color: var(--text-color);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1rem;
}

.nav-btn:hover {
    background: var(--text-color);
    color: var(--bg-color);
    border-color: var(--text-color);
}

.rec-content {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 2rem;
    flex-grow: 1;
}

.rec-author {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.rec-avatar {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    object-fit: cover;
}

.rec-info h4 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-color);
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.85rem 1.75rem;
    background: var(--text-color);
    color: var(--bg-color);
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    border: 1px solid var(--text-color);
}

.btn:hover {
    background: var(--bg-color);
    color: var(--text-color);
}

.btn-secondary {
    background: transparent;
    color: var(--text-color);
}

.btn-secondary:hover {
    background: var(--card-bg);
    border-color: var(--border-color);
}

/* Chat Modal */
.chat-modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 2000;
    opacity: 0;
    pointer-events: none;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.3s ease;
}

.chat-modal-overlay.active {
    opacity: 1;
    pointer-events: all;
}

.chat-window {
    width: 650px;
    max-width: 95%;
    height: 600px;
    max-height: 90vh;
    background: var(--bg-color);
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
    transform: scale(0.95) translateY(20px);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.chat-modal-overlay.active .chat-window {
    transform: scale(1) translateY(0);
}

.chat-header {
    background: var(--card-bg);
    color: var(--text-color);
    padding: 1.25rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    border-radius: 16px 16px 0 0;
}

.chat-header .close-btn {
    color: var(--text-muted);
}

.chat-header .close-btn:hover {
    color: var(--text-color);
}

.chat-messages {
    flex: 1;
    padding: 1.5rem;
    background: var(--bg-color);
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.chat-message {
    max-width: 80%;
    padding: 0.85rem 1rem;
    border-radius: 12px;
    font-size: 0.95rem;
}

.chat-message.bot {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    align-self: flex-start;
}

.chat-message.user {
    background: var(--text-color);
    color: var(--bg-color);
    align-self: flex-end;
}

.chat-message.user .chat-content {
    color: var(--bg-color);
}

.chat-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
    background: var(--card-bg);
    border-radius: 0 0 16px 16px;
}

.chat-input-wrapper {
    display: flex;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.4rem 0.6rem;
}

.chat-input-wrapper input {
    flex: 1;
    border: none;
    background: transparent;
    padding: 0.5rem;
    outline: none;
    color: var(--text-color);
    font-size: 0.95rem;
}

.chat-send-btn {
    background: var(--accent-color);
    color: white;
    border: none;
    width: 36px;
    height: 36px;
    border-radius: 6px;
    cursor: pointer;
    transition: opacity 0.2s;
}

.chat-send-btn:hover {
    opacity: 0.9;
}

/* Footer */
footer {
    padding: 4rem 0 2rem;
    text-align: center;
    border-top: 1px solid var(--border-color);
    margin-top: calc(var(--section-spacing) / 2);
}

.footer-social {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.footer-social a {
    font-size: 1.25rem;
    color: var(--text-muted);
}

.footer-social a:hover {
    color: var(--text-color);
}

.footer-text {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* Responsive Chat Modal for Mobile */
@media (max-width: 768px) {
    .chat-modal-overlay {
        align-items: flex-start;
        padding: 0;
        background: var(--bg-color);
        /* fully opaque background to hide everything behind */
        backdrop-filter: none;
    }

    .chat-window {
        width: 100%;
        max-width: 100%;
        height: 100dvh;
        /* Full viewport height natively */
        max-height: 100dvh;
        border-radius: 0;
        transform: translateY(20px);
        opacity: 0;
        box-shadow: none;
        /* Flat design */
    }

    .chat-modal-overlay.active .chat-window {
        transform: translateY(0);
        opacity: 1;
    }

    .chat-header {
        border-radius: 0;
        padding: 1.25rem 1.25rem;
        border-bottom: 1px solid var(--border-color);
    }

    .chat-messages {
        padding: 1.25rem;
    }

    .chat-footer {
        padding: 0.75rem 1.25rem;
        padding-bottom: max(1.25rem, env(safe-area-inset-bottom));
        /* Accommodate iPhone home bar securely */
        border-radius: 0;
    }

    .chat-message {
        max-width: 90%;
        font-size: 1rem;
        /* Slightly larger for mobile readability */
    }
}