/* ===== CSS Variables & Themes ===== */
:root {
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --max-width: 1100px;
    --nav-height: 70px;
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.3s ease;
}

[data-theme="light"] {
    --bg-primary: #f8f9fb;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-card-hover: #f0f4ff;
    --bg-nav: rgba(255, 255, 255, 0.85);
    --text-primary: #1a1a2e;
    --text-secondary: #4a4a6a;
    --text-muted: #7a7a9a;
    --accent: #4361ee;
    --accent-light: #e8edff;
    --accent-gradient: linear-gradient(135deg, #4361ee, #7209b7);
    --border: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 4px 12px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 4px 6px rgba(0, 0, 0, 0.05), 0 10px 30px rgba(0, 0, 0, 0.08);
    --tag-bg: #eef2ff;
    --tag-text: #4361ee;
    --hero-bg: linear-gradient(135deg, #f8f9fb 0%, #e8edff 100%);
}

[data-theme="dark"] {
    --bg-primary: #0f0f1a;
    --bg-secondary: #1a1a2e;
    --bg-card: #1e1e35;
    --bg-card-hover: #2a2a4a;
    --bg-nav: rgba(15, 15, 26, 0.9);
    --text-primary: #e8e8f0;
    --text-secondary: #b0b0cc;
    --text-muted: #7a7a9a;
    --accent: #6c83ff;
    --accent-light: #1e1e3a;
    --accent-gradient: linear-gradient(135deg, #6c83ff, #a855f7);
    --border: #2a2a4a;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.2), 0 4px 12px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 4px 6px rgba(0, 0, 0, 0.2), 0 10px 30px rgba(0, 0, 0, 0.25);
    --tag-bg: #1e1e3a;
    --tag-text: #6c83ff;
    --hero-bg: linear-gradient(135deg, #0f0f1a 0%, #1a1a2e 100%);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    transition: background-color var(--transition), color var(--transition);
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: var(--text-primary);
}

img {
    max-width: 100%;
}

ul {
    list-style: none;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--nav-height);
    background: var(--bg-nav);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    transition: background var(--transition), box-shadow var(--transition);
}

.navbar.scrolled {
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    position: relative;
    padding: 4px 0;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-gradient);
    border-radius: 2px;
    transition: width var(--transition);
}

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

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

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* Theme Toggle */
.theme-toggle {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.theme-toggle:hover {
    border-color: var(--accent);
    transform: rotate(15deg);
}

.theme-icon {
    font-size: 1.1rem;
    position: absolute;
    transition: transform 0.4s ease, opacity 0.4s ease;
}

[data-theme="light"] .theme-icon.sun {
    transform: rotate(0deg) scale(1);
    opacity: 1;
}

[data-theme="light"] .theme-icon.moon {
    transform: rotate(90deg) scale(0);
    opacity: 0;
}

[data-theme="dark"] .theme-icon.sun {
    transform: rotate(-90deg) scale(0);
    opacity: 0;
}

[data-theme="dark"] .theme-icon.moon {
    transform: rotate(0deg) scale(1);
    opacity: 1;
}

/* Hamburger */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.hamburger span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition);
}

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

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

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all var(--transition);
    border: none;
    text-decoration: none;
}

.btn-sm {
    padding: 8px 18px;
    font-size: 0.85rem;
}

.btn-lg {
    padding: 16px 36px;
    font-size: 1rem;
}

.btn-primary {
    background: var(--accent-gradient);
    color: #fff;
    box-shadow: 0 2px 8px rgba(67, 97, 238, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(67, 97, 238, 0.4);
    color: #fff;
}

.btn-outline {
    background: transparent;
    color: var(--accent);
    border: 2px solid var(--accent);
}

.btn-outline:hover {
    background: var(--accent);
    color: #fff;
    transform: translateY(-2px);
}

.download-icon {
    font-size: 1.1em;
    font-weight: 700;
}

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: calc(var(--nav-height) + 40px) 24px 60px;
    background: var(--hero-bg);
    position: relative;
    overflow: hidden;
}

.hero-content {
    max-width: var(--max-width);
    margin: 0 auto;
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-greeting {
    font-size: 1.1rem;
    color: var(--accent);
    font-weight: 600;
    letter-spacing: 2px;
    text-transform: uppercase;
    margin-bottom: 12px;
}

.hero-name {
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 12px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-title {
    font-size: clamp(1.2rem, 3vw, 1.8rem);
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 24px;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin: 0 auto 36px;
    line-height: 1.8;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 56px;
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
    flex-wrap: wrap;
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 2rem;
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* Decorative shape */
.hero-visual {
    position: absolute;
    top: 50%;
    right: -200px;
    transform: translateY(-50%);
    pointer-events: none;
}

.hero-shape {
    width: 500px;
    height: 500px;
    border-radius: 50%;
    background: var(--accent-gradient);
    opacity: 0.05;
    filter: blur(80px);
}

/* ===== Sections ===== */
.section {
    padding: 100px 0;
}

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

.section-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 56px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: var(--accent-gradient);
    border-radius: 4px;
    margin: 16px auto 0;
}

/* ===== About ===== */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: start;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-size: 1rem;
}

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

.about-details {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.detail-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    transition: all var(--transition);
    box-shadow: var(--shadow);
}

.detail-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.detail-icon {
    font-size: 2rem;
    margin-bottom: 12px;
}

.detail-card h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.detail-main {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

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

/* ===== Timeline (Experience) ===== */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border);
}

.timeline-item {
    position: relative;
    padding-left: 56px;
    margin-bottom: 48px;
}

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

.timeline-marker {
    position: absolute;
    left: 12px;
    top: 6px;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent-gradient);
    border: 3px solid var(--bg-primary);
    box-shadow: 0 0 0 3px var(--accent);
}

.timeline-content {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    box-shadow: var(--shadow);
    transition: all var(--transition);
}

.timeline-content:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 4px;
    flex-wrap: wrap;
    gap: 8px;
}

.timeline-header h3 {
    font-size: 1.2rem;
    font-weight: 700;
}

.company {
    color: var(--accent);
    font-weight: 500;
    font-size: 0.95rem;
}

.timeline-date {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
    white-space: nowrap;
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 4px 12px;
    border-radius: 20px;
}

.timeline-location {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.timeline-details {
    list-style: disc;
    padding-left: 20px;
}

.timeline-details li {
    color: var(--text-secondary);
    margin-bottom: 10px;
    font-size: 0.95rem;
    line-height: 1.7;
}

.timeline-details strong {
    color: var(--text-primary);
}

/* ===== Projects ===== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent-gradient);
    transform: scaleX(0);
    transition: transform var(--transition);
}

.project-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.project-card:hover::before {
    transform: scaleX(1);
}

.project-tag {
    display: inline-block;
    background: var(--tag-bg);
    color: var(--tag-text);
    font-size: 0.75rem;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 20px;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 16px;
}

.project-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.project-date {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 12px;
}

.project-card > p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 12px;
}

.project-card ul {
    list-style: disc;
    padding-left: 20px;
    margin-bottom: 20px;
}

.project-card li {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 6px;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.project-tech span {
    background: var(--tag-bg);
    color: var(--tag-text);
    font-size: 0.78rem;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 20px;
}

/* ===== Skills ===== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.skill-category {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    box-shadow: var(--shadow);
    transition: all var(--transition);
}

.skill-category:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.skill-category-icon {
    font-size: 2rem;
    margin-bottom: 12px;
}

.skill-category h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.skill-tags span {
    background: var(--tag-bg);
    color: var(--tag-text);
    font-size: 0.82rem;
    font-weight: 600;
    padding: 6px 14px;
    border-radius: 20px;
    transition: all var(--transition);
}

.skill-tags span:hover {
    background: var(--accent);
    color: #fff;
    transform: translateY(-2px);
}

/* ===== Certifications ===== */
.certs-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.cert-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: all var(--transition);
}

.cert-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent);
}

.cert-icon {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.cert-card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 8px;
}

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

/* ===== Contact ===== */
.contact-intro {
    text-align: center;
    color: var(--text-secondary);
    max-width: 600px;
    margin: -24px auto 48px;
    font-size: 1.05rem;
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: center;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.contact-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
}

.contact-icon {
    font-size: 1.5rem;
    min-width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--tag-bg);
    border-radius: var(--radius-sm);
}

.contact-item h4 {
    font-size: 0.9rem;
    font-weight: 700;
    margin-bottom: 2px;
}

.contact-item p,
.contact-item a {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.contact-item a:hover {
    color: var(--accent);
}

.contact-cta {
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: 24px 0;
    text-align: center;
}

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

/* ===== Back to Top ===== */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--accent-gradient);
    color: #fff;
    border: none;
    font-size: 1.3rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition);
    box-shadow: 0 4px 12px rgba(67, 97, 238, 0.3);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: 0 6px 20px rgba(67, 97, 238, 0.5);
}

/* ===== Scroll Animations ===== */
.timeline-item,
.project-card,
.skill-category,
.cert-card,
.detail-card,
.contact-item {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.timeline-item.animate-in,
.project-card.animate-in,
.skill-category.animate-in,
.cert-card.animate-in,
.detail-card.animate-in,
.contact-item.animate-in {
    opacity: 1;
    transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: var(--bg-nav);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow-lg);
    }

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

    .hamburger {
        display: flex;
    }

    .hero {
        padding-top: calc(var(--nav-height) + 20px);
    }

    .hero-name {
        font-size: 2.5rem;
    }

    .hero-stats {
        gap: 24px;
    }

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

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

    .contact-grid {
        grid-template-columns: 1fr;
        gap: 36px;
    }

    .timeline::before {
        left: 12px;
    }

    .timeline-item {
        padding-left: 44px;
    }

    .timeline-marker {
        left: 4px;
    }

    .timeline-header {
        flex-direction: column;
    }

    .section {
        padding: 64px 0;
    }

    .btn-sm {
        padding: 6px 12px;
        font-size: 0.8rem;
    }
}

@media (max-width: 480px) {
    .hero-name {
        font-size: 2rem;
    }

    .hero-description {
        font-size: 0.95rem;
    }

    .hero-stats {
        flex-direction: column;
        gap: 16px;
    }

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

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