/* =============================================
   CSS Variables - Theme System
   ============================================= */
:root {
    /* Shared colors */
    --color-orange: #f97316;
    --color-orange-hover: #ea580c;
    --color-blue: #3b82f6;
    --color-blue-hover: #2563eb;
    --color-white: #ffffff;

    /* Font */
    --font-main: 'Segoe UI', system-ui, -apple-system, sans-serif;

    /* Layout */
    --header-height: 70px;
    --container-max: 1200px;
    --radius: 12px;
    --radius-sm: 8px;

    /* Transitions */
    --transition: 0.3s ease;
}

/* Dark Theme (default) */
[data-theme="dark"] {
    --bg-primary: #0a0a0a;
    --bg-secondary: #111111;
    --bg-tertiary: #1a1a1a;
    --bg-card: #151515;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --text-muted: #707070;
    --border-color: #2a2a2a;
    --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.4);
    --shadow-card-hover: 0 8px 30px rgba(249, 115, 22, 0.15);
    --header-bg: rgba(10, 10, 10, 0.85);
    --header-blur: blur(12px);
    --skill-icon-bg: rgba(249, 115, 22, 0.1);
    --tag-bg: rgba(59, 130, 246, 0.15);
    --tag-text: var(--color-blue);
}

/* Light Theme */
[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #f0f1f3;
    --bg-card: #ffffff;
    --text-primary: #1a1a2e;
    --text-secondary: #555555;
    --text-muted: #888888;
    --border-color: #e0e0e0;
    --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.08);
    --shadow-card-hover: 0 8px 30px rgba(249, 115, 22, 0.12);
    --header-bg: rgba(255, 255, 255, 0.85);
    --header-blur: blur(12px);
    --skill-icon-bg: rgba(249, 115, 22, 0.08);
    --tag-bg: rgba(59, 130, 246, 0.1);
    --tag-text: var(--color-blue-hover);
}

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

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

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition), color var(--transition);
}

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

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

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

.accent {
    color: var(--color-orange);
}

.section-title {
    font-size: 2.2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 12px;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.05rem;
    max-width: 600px;
    margin: 0 auto 48px;
}

/* =============================================
   Header
   ============================================= */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: var(--header-bg);
    backdrop-filter: var(--header-blur);
    -webkit-backdrop-filter: var(--header-blur);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: background var(--transition);
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    font-size: 1.4rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

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

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-secondary);
    padding: 8px 0;
    position: relative;
    transition: color var(--transition);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-orange);
    transition: width var(--transition);
}

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

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

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

/* Theme Toggle */
.theme-toggle {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: all var(--transition);
}

.theme-toggle:hover {
    border-color: var(--color-orange);
    color: var(--color-orange);
}

/* 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);
    transition: all var(--transition);
    border-radius: 2px;
}

.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;
    justify-content: center;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all var(--transition);
    border: none;
    gap: 8px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-blue), var(--color-orange));
    color: var(--color-white);
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
    box-shadow: 0 6px 25px rgba(249, 115, 22, 0.4);
    transform: translateY(-2px);
}

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

.btn-outline:hover {
    background: var(--color-blue);
    color: var(--color-white);
    transform: translateY(-2px);
}

.btn-sm {
    padding: 8px 20px;
    font-size: 0.85rem;
}

/* =============================================
   Hero Section
   ============================================= */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: var(--header-height);
    background: var(--bg-primary);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -200px;
    right: -200px;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(249, 115, 22, 0.08) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: -150px;
    left: -150px;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.06) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

.hero-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 60px;
}

.hero-text {
    flex: 1;
}

.hero-greeting {
    color: var(--color-orange);
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 8px;
}

.hero-name {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 12px;
}

.hero-title {
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--color-blue);
    margin-bottom: 20px;
}

.hero-description {
    color: var(--text-secondary);
    font-size: 1.05rem;
    max-width: 520px;
    margin-bottom: 32px;
    line-height: 1.7;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

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

.hero-image-wrapper {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    border: 4px solid var(--color-orange);
    overflow: hidden;
    box-shadow: 0 0 40px rgba(249, 115, 22, 0.2);
    transition: box-shadow var(--transition);
}

.hero-image-wrapper:hover {
    box-shadow: 0 0 60px rgba(249, 115, 22, 0.35);
}

.hero-image-wrapper img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center 20%;
}

/* =============================================
   Skills Section
   ============================================= */
.skills {
    padding: 100px 0;
    background: var(--bg-secondary);
}

.skills .section-title {
    margin-bottom: 48px;
}

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

.skill-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 32px;
    transition: all var(--transition);
}

.skill-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-card-hover);
    border-color: var(--color-orange);
}

.skill-icon {
    width: 50px;
    height: 50px;
    border-radius: var(--radius-sm);
    background: var(--skill-icon-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    color: var(--color-orange);
    margin-bottom: 16px;
}

.skill-card h3 {
    font-size: 1.15rem;
    margin-bottom: 10px;
}

.skill-card p {
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.6;
}

/* =============================================
   Projects Section
   ============================================= */
.projects {
    padding: 100px 0;
    background: var(--bg-primary);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 28px;
    display: flex;
    flex-direction: column;
    transition: all var(--transition);
}

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

.project-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
    font-size: 1.6rem;
    color: var(--color-orange);
}

.project-links a {
    color: var(--text-secondary);
    font-size: 1.2rem;
    transition: color var(--transition);
}

.project-links a:hover {
    color: var(--color-blue);
}

.project-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 10px;
}

.project-description {
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.6;
    flex: 1;
    margin-bottom: 16px;
}

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

.project-tags span {
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.project-card-cta {
    border-style: dashed;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.project-card-cta .project-header {
    justify-content: center;
    font-size: 2rem;
}

/* =============================================
   About Section
   ============================================= */
.about {
    padding: 100px 0;
    background: var(--bg-secondary);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: 40px;
    margin-top: 48px;
}

.about-intro {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-secondary);
    margin-bottom: 36px;
}

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

.about-block {
    margin-bottom: 36px;
}

.about-block h3 {
    font-size: 1.2rem;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--color-orange);
}

/* Timeline */
.timeline {
    position: relative;
    padding-left: 24px;
    border-left: 2px solid var(--border-color);
}

.timeline-item {
    position: relative;
    padding-bottom: 24px;
}

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

.timeline-item::before {
    content: '';
    position: absolute;
    left: -29px;
    top: 6px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--color-orange);
    border: 2px solid var(--bg-secondary);
}

.timeline-item h4 {
    font-size: 1rem;
    margin-bottom: 4px;
}

.timeline-role {
    font-size: 0.88rem;
    color: var(--color-blue);
    font-weight: 500;
    display: block;
    margin-bottom: 6px;
}

.timeline-item p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* Certifications */
.certifications-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.cert-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.92rem;
    transition: border-color var(--transition);
}

.cert-item:hover {
    border-color: var(--color-orange);
}

.cert-item i {
    color: var(--color-orange);
    font-size: 1.1rem;
}

/* Tech Stack Sidebar */
.tech-stack-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 28px;
    position: sticky;
    top: calc(var(--header-height) + 24px);
}

.tech-stack-card h3 {
    font-size: 1.2rem;
    margin-bottom: 24px;
    color: var(--color-orange);
}

.tech-category {
    margin-bottom: 20px;
}

.tech-category:last-child {
    margin-bottom: 0;
}

.tech-category h4 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 10px;
}

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

.tech-tags span {
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.82rem;
    font-weight: 500;
    transition: all var(--transition);
}

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

/* =============================================
   Contact Section
   ============================================= */
.contact {
    padding: 100px 0;
    background: var(--bg-primary);
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin-bottom: 40px;
}

.contact-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 32px;
    text-align: center;
    transition: all var(--transition);
    display: block;
}

.contact-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-card-hover);
    border-color: var(--color-orange);
}

.contact-icon {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--skill-icon-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    color: var(--color-orange);
    margin: 0 auto 16px;
}

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

.contact-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 6px;
}

.contact-info {
    font-size: 0.82rem;
    color: var(--text-muted);
}

.contact-social {
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

.social-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    border: 2px solid var(--border-color);
    color: var(--text-primary);
    transition: all var(--transition);
}

.social-btn:hover {
    border-color: var(--color-blue);
    color: var(--color-blue);
    transform: translateY(-2px);
}

/* =============================================
   Footer
   ============================================= */
.footer {
    padding: 32px 0;
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

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

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

.footer-links {
    display: flex;
    gap: 20px;
}

.footer-links a {
    color: var(--text-secondary);
    font-size: 1.2rem;
    transition: color var(--transition);
}

.footer-links a:hover {
    color: var(--color-orange);
}

/* =============================================
   Animations
   ============================================= */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* =============================================
   Responsive Design
   ============================================= */
@media (max-width: 992px) {
    .about-content {
        grid-template-columns: 1fr;
    }

    .tech-stack-card {
        position: static;
    }

    .hero-name {
        font-size: 2.8rem;
    }
}

@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .nav {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: var(--bg-primary);
        border-bottom: 1px solid var(--border-color);
        flex-direction: column;
        padding: 24px;
        gap: 8px;
        transform: translateY(-100%);
        opacity: 0;
        pointer-events: none;
        transition: all var(--transition);
    }

    .nav.open {
        transform: translateY(0);
        opacity: 1;
        pointer-events: all;
    }

    .nav-link {
        padding: 12px 0;
        font-size: 1.05rem;
    }

    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
        gap: 40px;
        padding-top: 40px;
    }

    .hero-description {
        margin: 0 auto 32px;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-image-wrapper {
        width: 220px;
        height: 220px;
    }

    .hero-name {
        font-size: 2.4rem;
    }

    .section-title {
        font-size: 1.8rem;
    }

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

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

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

    .footer-content {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
}

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

    .hero-title {
        font-size: 1.2rem;
    }

    .hero-image-wrapper {
        width: 180px;
        height: 180px;
    }

    .container {
        padding: 0 16px;
    }

    .skills,
    .projects,
    .about,
    .contact {
        padding: 70px 0;
    }
}