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

:root {
    --bg-gradient-start: #0f172a;
    --bg-gradient-mid: #1e293b;
    --bg-gradient-end: #0f172a;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;
    --text-muted: #64748b;
    --header-bg: linear-gradient(90deg, rgba(59, 130, 246, 0.2), rgba(147, 51, 234, 0.2));
    --avatar-bg: linear-gradient(135deg, #3b82f6, #9333ea);
    --card-bg: rgba(30, 41, 59, 0.5);
    --card-border: #334155;
    --card-hover: rgba(59, 130, 246, 0.5);
    --nav-bg: rgba(15, 23, 42, 0.95);
    --nav-border: #334155;
    --nav-text: #94a3b8;
    --nav-active: #60a5fa;
    --tag-bg: rgba(59, 130, 246, 0.2);
    --tag-border: rgba(59, 130, 246, 0.3);
    --tag-text: #93c5fd;
    --skill-bg: linear-gradient(90deg, rgba(59, 130, 246, 0.2), rgba(147, 51, 234, 0.2));
    --skill-border: rgba(59, 130, 246, 0.3);
    --skill-text: #e2e8f0;
    --footer-bg: #0f172a;
    --footer-border: #334155;
    --link-hover: rgba(255, 255, 255, 0.2);
    --link-bg: rgba(255, 255, 255, 0.1);
    --title-gradient: linear-gradient(90deg, #60a5fa, #a78bfa);
}

body.light-mode {
    --bg-gradient-start: #f8fafc;
    --bg-gradient-mid: #e2e8f0;
    --bg-gradient-end: #f8fafc;
    --text-primary: #0f172a;
    --text-secondary: #334155;
    --text-tertiary: #475569;
    --text-muted: #64748b;
    --header-bg: linear-gradient(90deg, rgba(59, 130, 246, 0.1), rgba(147, 51, 234, 0.1));
    --avatar-bg: linear-gradient(135deg, #3b82f6, #9333ea);
    --card-bg: rgba(255, 255, 255, 0.8);
    --card-border: #cbd5e1;
    --card-hover: rgba(59, 130, 246, 0.3);
    --nav-bg: rgba(255, 255, 255, 0.95);
    --nav-border: #e2e8f0;
    --nav-text: #64748b;
    --nav-active: #3b82f6;
    --tag-bg: rgba(59, 130, 246, 0.1);
    --tag-border: rgba(59, 130, 246, 0.2);
    --tag-text: #1e40af;
    --skill-bg: linear-gradient(90deg, rgba(59, 130, 246, 0.1), rgba(147, 51, 234, 0.1));
    --skill-border: rgba(59, 130, 246, 0.2);
    --skill-text: #1e3a8a;
    --footer-bg: #f1f5f9;
    --footer-border: #cbd5e1;
    --link-hover: rgba(59, 130, 246, 0.1);
    --link-bg: rgba(59, 130, 246, 0.05);
    --title-gradient: linear-gradient(90deg, #3b82f6, #9333ea);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-mid) 50%, var(--bg-gradient-end) 100%);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background 0.3s ease, color 0.3s ease;
}

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

header {
    position: relative;
    overflow: hidden;
    padding: 64px 0;
}

.header-bg {
    position: absolute;
    inset: 0;
    background: var(--header-bg);
}

.header-content {
    position: relative;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 32px;
}

.avatar {
    width: 128px;
    height: 128px;
    border-radius: 50%;
    background: var(--avatar-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 48px;
    font-weight: bold;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.3);
}

.header-text {
    flex: 1;
    min-width: 300px;
}

h1 {
    font-size: 48px;
    font-weight: bold;
    margin-bottom: 8px;
    background: var(--title-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 24px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.description {
    font-size: 18px;
    color: var(--text-tertiary);
    margin-bottom: 24px;
}

.contact-links {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
}

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    background: var(--link-bg);
    border-radius: 8px;
    color: var(--text-primary);
    text-decoration: none;
    transition: background 0.3s;
}

.contact-link:hover {
    background: var(--link-hover);
}

.pdf-button {
    background: linear-gradient(135deg, #3b82f6, #9333ea) !important;
    font-weight: 600;
    transition: transform 0.2s, box-shadow 0.2s;
    cursor: pointer;
    border: none;
}

.pdf-button:hover {
    background: linear-gradient(135deg, #2563eb, #7c3aed) !important;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

nav {
    position: sticky;
    top: 0;
    z-index: 50;
    background: var(--nav-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--nav-border);
}

.nav-container {
    display: flex;
    overflow-x: auto;
    align-items: center;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 16px 24px;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    color: var(--nav-text);
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    white-space: nowrap;
}

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

.nav-btn.active {
    color: var(--nav-active);
    border-bottom-color: var(--nav-active);
}

main {
    padding: 48px 0;
}

section {
    display: none;
}

section.active {
    display: block;
}

.section-title {
    font-size: 32px;
    font-weight: bold;
    margin-bottom: 32px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.section-title::before {
    content: attr(data-icon);
    font-size: 32px;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 24px;
    transition: border-color 0.3s;
}

.card:hover {
    border-color: var(--card-hover);
}

.card-header {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: start;
    gap: 16px;
    margin-bottom: 16px;
}

.card-title {
    font-size: 20px;
    font-weight: bold;
    color: var(--nav-active);
    margin-bottom: 4px;
}

.card-company {
    font-size: 18px;
    color: var(--text-secondary);
}

.card-period {
    font-size: 14px;
    color: var(--text-muted);
}

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

.tag {
    padding: 6px 12px;
    background: var(--tag-bg);
    border: 1px solid var(--tag-border);
    border-radius: 6px;
    font-size: 14px;
    color: var(--tag-text);
}

.card-description {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.expand-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    background: none;
    border: none;
    color: var(--nav-active);
    cursor: pointer;
    font-size: 16px;
    padding: 8px 0;
}

.expand-btn:hover {
    color: var(--tag-text);
}

.achievements {
    display: none;
    margin-top: 16px;
    padding-left: 24px;
}

.achievements.show {
    display: block;
}

.achievements li {
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.skills-grid {
    display: grid;
    gap: 24px;
}

.skill-category {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 24px;
}

.skill-category h3 {
    font-size: 20px;
    font-weight: bold;
    color: var(--nav-active);
    margin-bottom: 16px;
}

.skill-items {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.skill-item {
    padding: 10px 16px;
    background: var(--skill-bg);
    border: 1px solid var(--skill-border);
    border-radius: 8px;
    color: var(--skill-text);
    transition: transform 0.2s;
}

.skill-item:hover {
    transform: scale(1.05);
}

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

.cert-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 24px;
    display: flex;
    gap: 16px;
    transition: border-color 0.3s;
}

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

.cert-icon {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--avatar-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.cert-info h3 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.cert-year {
    font-size: 14px;
    color: var(--text-tertiary);
}

footer {
    background: var(--footer-bg);
    border-top: 1px solid var(--footer-border);
    padding: 32px 0;
    margin-top: 64px;
    text-align: center;
}

.quote {
    color: var(--text-tertiary);
    font-style: italic;
    margin-bottom: 16px;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin: 24px 0;
}

.social-link {
    color: var(--text-tertiary);
    transition: color 0.3s;
}

.social-link:hover {
    color: var(--nav-active);
}

.copyright {
    color: var(--text-muted);
    font-size: 14px;
}

.icon {
    width: 20px;
    height: 20px;
    display: inline-block;
}

/* Theme toggle button */
.theme-toggle-nav {
    margin-left: auto;
    border-bottom: 2px solid transparent !important;
}

.theme-toggle-nav:hover {
    border-bottom-color: transparent !important;
}

.theme-toggle-nav .sun-icon {
    display: none;
}

.theme-toggle-nav .moon-icon {
    display: inline-block;
}

body.light-mode .theme-toggle-nav .sun-icon {
    display: inline-block;
}

body.light-mode .theme-toggle-nav .moon-icon {
    display: none;
}

@media (max-width: 768px) {
    h1 {
        font-size: 36px;
    }

    .subtitle {
        font-size: 20px;
    }

    .description {
        font-size: 16px;
    }

    .contact-links {
        flex-direction: column;
    }

    .nav-btn {
        padding: 12px 16px;
        font-size: 14px;
    }
}

@media print {
    body {
        background: white;
        color: black;
    }

    nav {
        display: none;
    }

    section {
        display: block !important;
        page-break-inside: avoid;
    }

    .card {
        page-break-inside: avoid;
        border: 1px solid #ddd;
        background: white;
    }

    .expand-btn {
        display: none;
    }

    .achievements {
        display: block !important;
    }

    header {
        padding: 20px 0;
    }

    .header-bg {
        display: none;
    }

    h1, .card-title, .section-title {
        color: #1e40af !important;
    }

    .tag, .skill-item {
        border: 1px solid #3b82f6;
        background: #eff6ff;
        color: #1e40af;
    }

    footer {
        display: none;
    }

    .pdf-button {
        display: none;
    }
}