/* ===== CSS Variables ===== */
:root {
    /* Soft Neutrals */
    --off-white: #F7F7F8;
    --light-gray: #ECEDEF;
    --warm-beige: #F3EFEA;
    --soft-sand: #E8E2D8;
    
    /* Muted Blues */
    --soft-blue: #E6F0FA;
    --steel-blue: #5F7C8A;
    --slate-blue: #6B7C93;
    --deep-navy: #1F2A44;
    
    /* Gentle Greens */
    --sage-green: #DCE6DF;
    --muted-green: #7FA89A;
    --olive-soft: #8A9A5B;
    --forest-muted: #2F5D50;
    
    /* Warm Accents */
    --soft-peach: #F6D6C9;
    --dusty-rose: #C48B9F;
    --warm-coral: #E07A5F;
    --muted-gold: #C9A24D;
    
    /* Text Colors */
    --charcoal: #2E2E2E;
    --soft-black: #1C1C1C;
    --cool-gray: #4A4A4A;
    
    /* Primary Theme Colors */
    --primary: #5F7C8A;
    --primary-dark: #1F2A44;
    --secondary: #6B7C93;
    --accent: #E07A5F;
    --dark: #2E2E2E;
    --light: #F7F7F8;
    --gray: #ECEDEF;
    --gradient: linear-gradient(135deg, #5F7C8A 0%, #1F2A44 100%);
    --shadow: 0 4px 6px -1px rgba(31, 42, 68, 0.08);
    --shadow-lg: 0 10px 15px -3px rgba(31, 42, 68, 0.1);
    --radius: 12px;
    --transition: all 0.3s ease;
}

/* ===== Reset & Base ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--light);
    color: var(--dark);
    line-height: 1.6;
    position: relative;
}

/* AI/Data Science Background Pattern */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
    background-image: 
        /* Soft gradient blobs */
        radial-gradient(circle at 10% 20%, rgba(95, 124, 138, 0.06) 0%, transparent 50%),
        radial-gradient(circle at 90% 80%, rgba(31, 42, 68, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(127, 168, 154, 0.04) 0%, transparent 60%),
        radial-gradient(circle at 80% 20%, rgba(224, 122, 95, 0.03) 0%, transparent 40%),
        radial-gradient(circle at 20% 80%, rgba(201, 162, 77, 0.03) 0%, transparent 40%),
        /* Subtle grid pattern */
        linear-gradient(rgba(95, 124, 138, 0.04) 1px, transparent 1px),
        linear-gradient(90deg, rgba(95, 124, 138, 0.04) 1px, transparent 1px);
    background-size: 
        100% 100%,
        100% 100%,
        100% 100%,
        100% 100%,
        100% 100%,
        60px 60px,
        60px 60px;
}

/* Floating particles animation */
body::after {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
    background-image:
        /* Small dots like data points */
        radial-gradient(circle, rgba(95, 124, 138, 0.12) 1.5px, transparent 1.5px),
        radial-gradient(circle, rgba(127, 168, 154, 0.1) 1px, transparent 1px),
        radial-gradient(circle, rgba(224, 122, 95, 0.08) 1px, transparent 1px);
    background-size: 
        120px 120px,
        180px 180px,
        240px 240px;
    background-position:
        0 0,
        60px 60px,
        120px 30px;
    animation: floatParticles 80s linear infinite;
}

@keyframes floatParticles {
    0% {
        transform: translateY(0) translateX(0);
    }
    50% {
        transform: translateY(-20px) translateX(10px);
    }
    100% {
        transform: translateY(0) translateX(0);
    }
}

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

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 1.5rem;
}

.nav-menu a {
    font-weight: 500;
    color: var(--secondary);
    transition: var(--transition);
    font-size: 0.95rem;
}

.nav-menu a:hover {
    color: var(--warm-coral);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--dark);
    transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient);
    color: white;
    text-align: center;
    padding: 6rem 2rem 4rem;
}

.hero-content h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 700;
    margin-bottom: 1rem;
}

.highlight {
    position: relative;
}

.highlight::after {
    content: '';
    position: absolute;
    bottom: 5px;
    left: 0;
    width: 100%;
    height: 8px;
    background: rgba(224, 122, 95, 0.4);
    z-index: -1;
}

.tagline {
    font-size: clamp(1.1rem, 2.5vw, 1.4rem);
    font-weight: 500;
    margin-bottom: 0.5rem;
    opacity: 0.95;
}

.subtitle {
    font-size: 1.05rem;
    opacity: 0.85;
    margin-bottom: 2rem;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 0.875rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    transition: var(--transition);
    cursor: pointer;
}

.hero .btn-primary {
    background: var(--warm-coral);
    color: white;
}

.hero .btn-primary:hover {
    background: white;
    color: var(--warm-coral);
}

.btn-primary {
    background: var(--warm-coral);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    background: var(--primary-dark);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: white;
    color: var(--primary);
}

/* ===== Sections ===== */
.section {
    padding: 5rem 2rem;
}

.section-alt {
    background: var(--warm-beige);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    font-size: 2.25rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--gradient);
    border-radius: 2px;
}

/* ===== About ===== */
.about-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 3rem;
    align-items: start;
}

.about-text p {
    margin-bottom: 1rem;
    color: var(--secondary);
    font-size: 1.05rem;
    text-align: justify;
}

.about-text strong {
    color: var(--dark);
}

.skills h3 {
    margin-bottom: 1rem;
    color: var(--dark);
}

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

.skill-tags span {
    background: var(--gray);
    padding: 0.5rem 1rem;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 500;
    transition: var(--transition);
}

.skill-tags span:hover {
    background: var(--steel-blue);
    color: white;
}

/* ===== Timeline (Experience) ===== */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--gradient);
    border-radius: 2px;
}

.timeline-item {
    position: relative;
    padding-left: 2.5rem;
    margin-bottom: 2.5rem;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -6px;
    top: 5px;
    width: 15px;
    height: 15px;
    background: var(--warm-coral);
    border-radius: 50%;
    border: 3px solid white;
    box-shadow: var(--shadow);
}

.timeline-date {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--steel-blue);
    margin-bottom: 0.5rem;
}

.timeline-content {
    background: var(--off-white);
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.timeline-content h3 {
    color: var(--dark);
    margin-bottom: 0.25rem;
}

.timeline-content h4 {
    color: var(--secondary);
    font-weight: 500;
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
}

.timeline-content p {
    color: var(--secondary);
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
    text-align: justify;
}

.exp-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-top: 0.5rem;
}

.exp-tags span {
    background: var(--gray);
    padding: 0.25rem 0.6rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--secondary);
}

/* ===== Projects ===== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 1.5rem;
}

.project-card {
    background: white;
    padding: 1.75rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border-left: 4px solid var(--warm-coral);
    transition: var(--transition);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.project-card h3 {
    margin-bottom: 0.75rem;
    color: var(--dark);
    font-size: 1.15rem;
}

.project-card p {
    color: var(--secondary);
    margin-bottom: 1rem;
    font-size: 0.95rem;
    text-align: justify;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.project-tags span {
    background: var(--gray);
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 500;
}

.project-link {
    color: var(--warm-coral);
    font-weight: 600;
    font-size: 0.9rem;
    transition: var(--transition);
}

.project-link:hover {
    color: var(--primary-dark);
}

.more-projects {
    text-align: center;
    margin-top: 2.5rem;
}

/* ===== Publications ===== */
.publications-list {
    max-width: 900px;
    margin: 0 auto;
}

.publication-item {
    background: var(--off-white);
    padding: 2rem;
    border-radius: var(--radius);
    margin-bottom: 1rem;
    border-left: 4px solid var(--muted-green);
}

.publication-item h3 {
    color: var(--dark);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.pub-venue {
    color: var(--muted-green);
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
}

.publication-item p {
    color: var(--secondary);
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
    text-align: justify;
}

/* ===== Skills Grid ===== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 1.5rem;
}

.skill-category {
    background: white;
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.skill-category:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.skill-category h3 {
    color: var(--dark);
    margin-bottom: 0.75rem;
    font-size: 1.05rem;
}

.skill-category p {
    color: var(--secondary);
    font-size: 0.9rem;
    line-height: 1.7;
}

/* ===== Education ===== */
.education-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.education-card {
    background: var(--off-white);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.education-card h3 {
    color: var(--dark);
    margin-bottom: 0.25rem;
}

.education-card h4 {
    color: var(--steel-blue);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.edu-date {
    font-size: 0.9rem;
    color: var(--secondary);
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.education-card p {
    color: var(--secondary);
    font-size: 0.95rem;
    text-align: justify;
}

.certification {
    margin-top: 2rem;
}

.certification h3 {
    text-align: center;
    color: var(--dark);
    margin-bottom: 1.5rem;
}

.cert-card {
    background: var(--off-white);
    border-radius: var(--radius);
    padding: 2rem;
    max-width: 900px;
    margin: 0 auto;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--muted-gold);
}

.cert-header {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--gray);
}

.cert-icon {
    font-size: 2.5rem;
}

.cert-header h4 {
    color: var(--dark);
    font-size: 1.25rem;
    margin-bottom: 0.25rem;
}

.cert-header h4 a {
    color: var(--steel-blue);
    transition: var(--transition);
}

.cert-header h4 a:hover {
    color: var(--warm-coral);
}

.cert-issuer {
    color: var(--secondary);
    font-size: 0.95rem;
    font-weight: 500;
}

.cert-modules {
    display: grid;
    gap: 1rem;
}

.cert-module {
    background: white;
    padding: 1rem 1.25rem;
    border-radius: 8px;
}

.cert-module h5 {
    color: var(--dark);
    font-size: 1rem;
    margin-bottom: 0.5rem;
}

.cert-module p {
    color: var(--secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    text-align: justify;
}

.cert-card .btn {
    display: inline-block;
}

/* ===== Skills Graph ===== */
.skills-subtitle {
    text-align: center;
    color: var(--secondary);
    margin-bottom: 2rem;
    font-size: 1rem;
}

#skills-graph {
    width: 100%;
    height: 600px;
    background: #ffffff;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    position: relative;
    border: 1px solid var(--gray);
}

#skills-graph svg {
    display: block;
    position: relative;
    z-index: 1;
}

#skill-tooltip {
    position: absolute;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    padding: 0.875rem 1.25rem;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.15), 0 0 0 1px rgba(0,0,0,0.05);
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s ease;
    z-index: 1000;
    font-size: 0.9rem;
    color: var(--dark);
    max-width: 220px;
}

#skill-tooltip strong {
    color: var(--dark);
    font-size: 1rem;
}

@media (max-width: 768px) {
    #skills-graph {
        height: 500px;
    }
}

/* ===== Contact ===== */
.contact-content {
    text-align: center;
}

.contact-content > p {
    font-size: 1.1rem;
    color: var(--secondary);
    margin-bottom: 2rem;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
    margin-bottom: 1.5rem;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 1.5rem;
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    font-weight: 500;
    transition: var(--transition);
    font-size: 0.95rem;
}

.contact-link:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    color: var(--warm-coral);
}

.contact-link .icon {
    font-size: 1.25rem;
}

.location {
    color: var(--secondary);
    font-size: 1rem;
}

/* ===== Footer ===== */
.footer {
    background: var(--deep-navy);
    color: var(--light-gray);
    text-align: center;
    padding: 2rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: white;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        transition: var(--transition);
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 6px);
    }

    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -6px);
    }

    .about-content {
        grid-template-columns: 1fr;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .projects-grid {
        grid-template-columns: 1fr;
    }

    .education-grid {
        grid-template-columns: 1fr;
    }

    .timeline::before {
        left: 0;
    }

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