:root {
    /* Color Palette */
    --primary: #2E3192;
    --primary-dark: #1a1c5e;
    --primary-light: #5256c9;
    --secondary: #00A99D;
    --secondary-dark: #007a72;
    --accent: #FFB347; /* Warm accent for highlights */
    
    --text-main: #2D3748;
    --text-muted: #718096;
    --text-light: #F7FAFC;
    
    --bg-body: #F7FAFC;
    --bg-card: #FFFFFF;
    --bg-overlay: rgba(255, 255, 255, 0.85);
    
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.07);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
    
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-heading: 'Poppins', var(--font-sans);
    
    --header-height: 70px;
}

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

body {
    font-family: var(--font-sans);
    line-height: 1.7;
    color: var(--text-main);
    background-color: var(--bg-body);
    -webkit-font-smoothing: antialiased;
}

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

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.3;
    color: var(--primary);
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
.header {
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(0,0,0,0.05);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    height: var(--header-height);
    display: flex;
    align-items: center;
    box-shadow: var(--shadow-sm);
}

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

.header-logo img {
    height: 40px;
    width: auto;
    display: block;
}

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

.header-nav a {
    color: var(--text-main);
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    padding: 5px 0;
}

.header-nav a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--secondary);
    transition: width 0.3s ease;
}

.header-nav a:hover {
    color: var(--primary);
}

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

.hamburger {
    display: none;
}

/* Hero Section */
.hero {
    min-height: 90vh;
    padding-top: var(--header-height);
    display: flex;
    align-items: center;
    background: linear-gradient(120deg, #fdfbfb 0%, #ebedee 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(0, 169, 157, 0.1) 0%, rgba(46, 49, 146, 0.05) 70%);
    border-radius: 50%;
    z-index: 0;
}

.hero-content {
    max-width: 600px;
    position: relative;
    z-index: 2;
}

.hero-title {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    color: var(--primary-dark);
    letter-spacing: -0.02em;
}

.hero-subtitle {
    display: block;
    font-size: 1.25rem;
    color: var(--secondary);
    font-weight: 500;
    margin-top: 0.5rem;
}

.hero-role {
    font-size: 1.5rem;
    color: var(--text-muted);
    margin-bottom: 2rem;
    font-weight: 400;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-main);
    margin-bottom: 2.5rem;
    line-height: 1.8;
}

.hero-cta {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background-color: var(--primary);
    color: white;
    padding: 14px 28px;
    border-radius: 50px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(46, 49, 146, 0.3);
}

.hero-cta:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(46, 49, 146, 0.4);
}

.hero-eyecatch {
    position: absolute;
    top: 50%;
    right: 5%;
    transform: translateY(-50%);
    width: 45%;
    max-width: 600px;
    z-index: 1;
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-eyecatch img {
    width: 100%;
    height: auto;
    object-fit: contain;
    filter: drop-shadow(0 20px 30px rgba(0,0,0,0.1));
}

/* Section Common */
.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
    display: inline-block;
    left: 50%;
    transform: translateX(-50%);
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: var(--secondary);
    margin: 10px auto 0;
    border-radius: 2px;
}

/* Skills */
.skills {
    padding: 100px 0;
    background-color: white;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.skill-category {
    background: white;
    padding: 30px;
    border-radius: var(--radius-md);
    border: 1px solid #edf2f7;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s ease;
}

.skill-category:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
    border-color: var(--secondary);
}

.skill-category-title {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--primary);
    border-bottom: 2px solid #edf2f7;
    padding-bottom: 10px;
}

.skill-category-title i {
    color: var(--secondary);
    font-size: 1.1em;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.skill-tag {
    background: #f7fafc;
    color: var(--primary);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    border: 1px solid #e2e8f0;
}

/* Achievements & Cards */
.achievements {
    padding: 100px 0;
    background-color: #f8fafc;
}

.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.achievement-card {
    background: white;
    padding: 30px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    display: flex;
    gap: 20px;
    transition: all 0.3s ease;
    border: 1px solid transparent;
}

.achievement-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(0, 169, 157, 0.2);
}

.achievement-icon {
    width: 50px;
    height: 50px;
    background: rgba(46, 49, 146, 0.05);
    color: var(--primary);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.achievement-title {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--primary-dark);
}

.achievement-desc {
    font-size: 0.95rem;
    color: var(--text-muted);
    line-height: 1.6;
}

/* Services */
.services {
    padding: 100px 0;
    background-color: white;
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.service-card {
    background: white;
    border-radius: var(--radius-md);
    padding: 40px 30px;
    text-align: center;
    border: 1px solid #edf2f7;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.service-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-color: var(--secondary);
}

.card-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 25px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    box-shadow: 0 10px 20px rgba(46, 49, 146, 0.2);
}

.card-title {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: var(--primary-dark);
}

/* Profile Page Specifics */
.profile-page {
    padding-top: calc(var(--header-height) + 60px);
    padding-bottom: 80px;
}

.profile-hero {
    display: flex;
    align-items: center;
    gap: 60px;
    margin-bottom: 80px;
    background: white;
    padding: 40px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.profile-image-wrapper {
    position: relative;
}

.profile-image {
    width: 240px;
    height: 240px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid white;
    box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.profile-header-info h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
    color: var(--primary-dark);
}

.profile-header-info .en-name {
    font-size: 1.5rem;
    font-weight: 300;
    color: var(--text-muted);
    margin-left: 15px;
}

.profile-header-info .role {
    font-size: 1.4rem;
    color: var(--secondary);
    font-weight: 500;
    margin-bottom: 1.5rem;
    display: block;
}

.profile-social-links {
    display: flex;
    gap: 15px;
}

.social-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background-color: #f7fafc;
    color: var(--text-main);
    border-radius: 8px;
    font-weight: 500;
    transition: all 0.2s ease;
    border: 1px solid #e2e8f0;
}

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

/* Timeline */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 0;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 20px; /* Adjusted for mobile first, can be centered for desktop if desired */
    width: 2px;
    background: #e2e8f0;
}

.timeline-item {
    position: relative;
    margin-bottom: 50px;
    padding-left: 60px;
}

.timeline-dot {
    position: absolute;
    left: 11px;
    top: 0;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--secondary);
    border: 4px solid #fff;
    box-shadow: 0 0 0 2px var(--secondary);
    z-index: 1;
}

.timeline-date {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--secondary);
    margin-bottom: 5px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.timeline-content {
    background: white;
    padding: 25px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    border: 1px solid #edf2f7;
    transition: all 0.3s ease;
}

.timeline-content:hover {
    box-shadow: var(--shadow-md);
    transform: translateX(5px);
}

.timeline-title {
    font-size: 1.3rem;
    color: var(--primary);
    margin-bottom: 5px;
}

.timeline-company {
    font-size: 1.1rem;
    color: var(--text-main);
    font-weight: 500;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.timeline-company i {
    color: var(--text-muted);
}

.timeline-desc ul {
    list-style-type: none;
    margin-top: 10px;
}

.timeline-desc li {
    position: relative;
    padding-left: 20px;
    margin-bottom: 8px;
    font-size: 0.95rem;
    color: var(--text-main);
}

.timeline-desc li::before {
    content: '•';
    color: var(--secondary);
    position: absolute;
    left: 0;
    font-weight: bold;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px dashed #e2e8f0;
}

.tech-badge {
    font-size: 0.8rem;
    padding: 4px 10px;
    background: #f0f4f8;
    color: var(--text-muted);
    border-radius: 4px;
}

/* Footer */
.footer {
    background-color: #1a202c;
    color: white;
    padding: 60px 0;
    text-align: center;
}

.footer-logo img {
    height: 35px;
    opacity: 0.9;
    margin-bottom: 20px;
}

.footer-links {
    margin-top: 30px;
    display: flex;
    justify-content: center;
    gap: 30px;
}

.footer-link {
    color: #a0aec0;
    font-size: 0.9rem;
    transition: color 0.2s;
}

.footer-link:hover {
    color: white;
}

/* Utilities */
.highlight {
    color: var(--secondary);
    font-weight: 600;
}

.mb-2 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 2rem; }
.mt-4 { margin-top: 2rem; }

/* OSS Grid */
.oss-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.oss-card {
    text-decoration: none;
}

.skill-description {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-top: 3rem;
    color: var(--primary);
    font-weight: 500;
    transition: all 0.2s ease;
}

.back-link:hover {
    color: var(--secondary);
    transform: translateX(-5px);
}

/* Responsive - Tablet */
@media (max-width: 992px) {
    .hero {
        flex-direction: column;
        text-align: center;
        padding-top: 120px;
        min-height: auto;
        padding-bottom: 60px;
    }

    .hero-eyecatch {
        position: relative;
        width: 80%;
        max-width: 400px;
        margin: 40px auto 0;
        right: auto;
        transform: none;
        top: auto;
    }

    .hero-content {
        margin: 0 auto;
        padding: 0 20px;
    }

    .hero-cta {
        margin: 0 auto;
    }

    .profile-hero {
        flex-direction: column;
        text-align: center;
        gap: 30px;
    }

    .profile-social-links {
        justify-content: center;
    }

    .services {
        padding: 60px 0;
    }

    .achievements {
        padding: 60px 0;
    }

    .services-grid,
    .achievements-grid,
    .skills-grid,
    .oss-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

/* Responsive - Mobile */
@media (max-width: 768px) {
    :root {
        --header-height: 60px;
    }

    /* Header & Navigation */
    .hamburger {
        display: flex;
        flex-direction: column;
        cursor: pointer;
        padding: 10px;
        z-index: 1001;
    }

    .hamburger span {
        width: 25px;
        height: 2px;
        background: var(--primary);
        margin: 3px 0;
        transition: 0.3s;
    }

    .header-nav {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        background: white;
        flex-direction: column;
        padding: 100px 40px;
        transition: right 0.3s ease;
        box-shadow: -10px 0 30px rgba(0,0,0,0.1);
        gap: 20px;
    }

    .header-nav.active {
        right: 0;
    }

    .header-nav a {
        font-size: 1.1rem;
    }

    .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);
    }

    .header-logo img {
        height: 32px;
    }

    /* Hero */
    .hero {
        padding-top: 100px;
        padding-bottom: 40px;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-role {
        font-size: 1.1rem;
        margin-bottom: 1.5rem;
    }

    .hero-description {
        font-size: 0.95rem;
        margin-bottom: 1.5rem;
    }

    .hero-cta {
        padding: 12px 24px;
        font-size: 0.9rem;
    }

    .hero-eyecatch {
        width: 90%;
        max-width: 280px;
        margin-top: 30px;
    }

    /* Sections */
    .section-title {
        font-size: 1.6rem;
        margin-bottom: 2rem;
    }

    .services,
    .achievements {
        padding: 50px 0;
    }

    /* Cards */
    .service-card {
        padding: 30px 20px;
    }

    .card-icon {
        width: 60px;
        height: 60px;
        font-size: 1.5rem;
        margin-bottom: 20px;
    }

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

    .service-card p {
        font-size: 0.9rem;
    }

    .achievement-card {
        padding: 20px;
        gap: 15px;
    }

    .achievement-icon {
        width: 45px;
        height: 45px;
        font-size: 1.2rem;
    }

    .achievement-title {
        font-size: 1rem;
    }

    .achievement-desc {
        font-size: 0.85rem;
    }

    /* Profile page */
    .profile-page {
        padding-top: calc(var(--header-height) + 30px);
        padding-bottom: 50px;
    }

    .profile-hero {
        padding: 24px 20px;
        margin-bottom: 40px;
    }

    .profile-image {
        width: 140px;
        height: 140px;
    }

    .profile-header-info h1 {
        font-size: 1.8rem;
    }

    .profile-header-info .en-name {
        display: block;
        margin-left: 0;
        margin-top: 5px;
        font-size: 1.1rem;
    }

    .profile-header-info .role {
        font-size: 1rem;
        margin-bottom: 1rem;
    }

    .profile-header-info p {
        font-size: 0.9rem;
    }

    .profile-social-links {
        flex-wrap: wrap;
        gap: 10px;
    }

    .social-btn {
        padding: 8px 14px;
        font-size: 0.85rem;
    }

    /* Timeline */
    .timeline {
        padding: 20px 0;
    }

    .timeline::before {
        left: 15px;
    }

    .timeline-item {
        padding-left: 45px;
        margin-bottom: 30px;
    }

    .timeline-dot {
        left: 6px;
        width: 18px;
        height: 18px;
    }

    .timeline-date {
        font-size: 0.8rem;
    }

    .timeline-content {
        padding: 18px;
    }

    .timeline-content:hover {
        transform: none;
    }

    .timeline-title {
        font-size: 1.05rem;
    }

    .timeline-company {
        font-size: 0.95rem;
        flex-wrap: wrap;
    }

    .timeline-desc p,
    .timeline-desc li {
        font-size: 0.85rem;
    }

    .tech-badge {
        font-size: 0.75rem;
        padding: 3px 8px;
    }

    /* Skills */
    .skill-category {
        padding: 20px;
    }

    .skill-category-title {
        font-size: 1.1rem;
        margin-bottom: 1rem;
    }

    .skill-tag {
        font-size: 0.8rem;
        padding: 5px 12px;
    }

    .skill-description {
        font-size: 0.85rem;
    }

    /* Footer */
    .footer {
        padding: 40px 0;
    }

    .footer-logo img {
        height: 28px;
    }

    .footer p {
        font-size: 0.85rem;
    }

    .footer-links {
        flex-direction: column;
        gap: 15px;
        margin-top: 20px;
    }
}

/* Extra small screens */
@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .hero-title {
        font-size: 1.7rem;
    }

    .hero-subtitle {
        font-size: 0.9rem;
    }

    .profile-image {
        width: 110px;
        height: 110px;
    }

    .profile-header-info h1 {
        font-size: 1.5rem;
    }

    .profile-header-info .en-name {
        font-size: 0.95rem;
    }

    .profile-header-info .role {
        font-size: 0.9rem;
    }

    .section-title {
        font-size: 1.4rem;
    }

    .social-btn {
        flex: 1;
        justify-content: center;
        min-width: 100px;
    }

    .timeline-item {
        padding-left: 40px;
    }

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

    .timeline-dot {
        left: 3px;
        width: 16px;
        height: 16px;
    }

    .timeline-content {
        padding: 15px;
    }

    .achievement-card {
        flex-direction: column;
        text-align: center;
    }

    .achievement-icon {
        margin: 0 auto;
    }
}