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

:root {
    --primary-color: #2f343a;
    --secondary-color: #6b7280;
    --accent-color: #9ca3af;
    --dark-bg: #1f2933;
    --light-bg: #f4f5f7;
    --surface-color: #ffffff;
    --muted-surface: #eceff3;
    --text-dark: #2b2f33;
    --text-light: #fff;
    --border-color: #d7dbe0;
    --gray: #5f6670;
}

html {
    font-size: 15px;
    scroll-behavior: smooth;
}

body {
    font-family: "Inter", "Segoe UI", Arial, sans-serif;
    background: var(--light-bg);
    color: var(--text-dark);
    line-height: 1.6;
    font-weight: 400;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: var(--secondary-color);
}

header {
    background: var(--primary-color);
    color: var(--text-light);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

header.header-hidden {
    transform: translateY(-100%);
}

.header-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    max-width: 1200px;
    margin: 0 auto;
    position: relative;
}

.header-content {
    display: flex;
    align-items: center;
    gap: 15px;
    flex: 1;
    min-width: 0;
}

header img {
    border-radius: 50%;
    width: 80px;
    height: 80px;
    object-fit: cover;
    border: 3px solid var(--secondary-color);
}

.header-text {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    text-align: center;
}

.header-text h1 {
    font-size: 1.3rem;
    font-weight: 700;
    margin: 0;
    padding: 0;
    line-height: 1;
}

.header-text .tagline {
    font-size: 0.85rem;
    color: #f1f3f5;
    font-weight: 500;
    margin: 0;
    padding: 0;
    line-height: 1;
}

.cv-link {
    width: 42px;
    height: 42px;
    border: 1px solid rgba(255, 255, 255, 0.45);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 10px;
    transition: background 0.3s ease, border-color 0.3s ease, transform 0.3s ease;
    order: 2;
}

.cv-link:hover {
    background: rgba(255, 255, 255, 0.12);
    border-color: var(--text-light);
    transform: translateY(-2px);
}

.cv-icon {
    width: 20px;
    height: 24px;
    border: 2px solid var(--text-light);
    border-radius: 3px;
    position: relative;
    display: inline-block;
}

.cv-icon::before {
    content: '';
    position: absolute;
    top: -2px;
    right: -2px;
    border-top: 8px solid var(--text-light);
    border-left: 8px solid transparent;
}

.cv-icon::after {
    content: 'CV';
    position: absolute;
    left: 50%;
    top: 52%;
    transform: translate(-50%, -50%);
    color: var(--text-light);
    font-size: 0.45rem;
    font-weight: 700;
}

.nav-menu {
    width: 100%;
    order: 3;
}

.nav-menu ul {
    list-style: none;
    display: none;
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding: 15px 0;
    margin-top: 10px;
    border-top: 1px solid rgba(255, 255, 255, 0.3);
}

.nav-menu.active ul {
    display: flex;
}

.nav-menu ul li a {
    color: var(--text-light);
    text-decoration: none;
    font-weight: 500;
    display: block;
    padding: 8px 0;
    transition: color 0.3s ease;
}

.nav-menu ul li a:hover {
    color: var(--secondary-color);
}

.menu-toggle {
    background: none;
    border: none;
    color: var(--text-light);
    font-size: 1.8rem;
    cursor: pointer;
    padding: 5px;
    display: flex;
    order: 2;
}

.menu-toggle:hover {
    color: var(--secondary-color);
}

section {
    padding: 2rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    scroll-margin-top: 120px;
}

section h2 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    text-align: center;
    position: relative;
    padding-bottom: 12px;
    font-weight: 700;
}

section h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 2px;
    background: var(--secondary-color);
    border-radius: 1px;
}

#about {
    background: var(--muted-surface);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
}

.about-text {
    line-height: 1.7;
}

.about-text p {
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.contact-info {
    background: var(--surface-color);
    padding: 1.6rem;
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.contact-info h3 {
    color: var(--primary-color);
    margin-bottom: 1.2rem;
    font-size: 1.1rem;
}

.contact-info p {
    margin-bottom: 0.8rem;
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.95rem;
}

.contact-info a {
    font-weight: 500;
}

.skills-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.skill-category {
    background: var(--surface-color);
    padding: 1.2rem;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.skill-category h3 {
    color: var(--primary-color);
    margin-bottom: 0.8rem;
    font-size: 1rem;
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 6px;
}

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

.skill-tag {
    background: var(--primary-color);
    color: white;
    padding: 6px 13px;
    border-radius: 18px;
    font-size: 0.85rem;
    font-weight: 500;
    display: inline-block;
    transition: all 0.3s ease;
}

.skill-tag:hover {
    background: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(47, 52, 58, 0.18);
}

.education-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.education-card {
    background: var(--surface-color);
    padding: 1.6rem;
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.education-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.4rem;
    font-size: 1.1rem;
}

.education-card .institute {
    font-weight: 600;
    color: var(--secondary-color);
    margin-bottom: 0.2rem;
    font-size: 0.95rem;
}

.education-card .year {
    color: #999;
    font-size: 0.85rem;
    margin-bottom: 0.8rem;
}

.section-intro {
    max-width: 800px;
    margin: 0 auto 1.5rem;
    color: var(--gray);
    text-align: center;
    line-height: 1.7;
}

.related-certificates {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 1rem;
}

.related-certificates a {
    border: 1px solid var(--border-color);
    border-radius: 18px;
    color: var(--primary-color);
    display: inline-block;
    font-size: 0.82rem;
    font-weight: 600;
    padding: 6px 12px;
    transition: background 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.related-certificates a:hover {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: var(--text-light);
}

.certificates-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.certificate-card {
    background: var(--surface-color);
    padding: 1.6rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--secondary-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    display: block;
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}

.certificate-card:hover {
    border-color: var(--secondary-color);
    transform: translateY(-4px);
    box-shadow: 0 8px 16px rgba(47, 52, 58, 0.14);
}

.certificate-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.35rem;
    font-size: 1.1rem;
}

.certificate-card p {
    color: var(--gray);
    font-size: 0.9rem;
}

.experience-card {
    background: var(--surface-color);
    padding: 1.6rem;
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    margin-bottom: 1.5rem;
}

.experience-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.4rem;
    font-size: 1.15rem;
}

.experience-card .company {
    font-weight: 700;
    color: var(--secondary-color);
    margin-bottom: 0.2rem;
    font-size: 1rem;
}

.experience-card .details {
    color: var(--gray);
    font-size: 0.9rem;
    margin-bottom: 0.8rem;
    font-weight: 500;
}

.experience-card p {
    line-height: 1.7;
}

.company-services {
    margin-top: 1rem;
    padding-left: 1.2rem;
}

.company-services li {
    margin-bottom: 0.65rem;
    line-height: 1.6;
}

.company-services strong {
    color: var(--primary-color);
}

#projects {
    background: var(--surface-color);
}

.project-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.project-card {
    background: var(--surface-color);
    padding: 1.8rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(47, 52, 58, 0.14);
}

.project-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.4rem;
    font-size: 1.15rem;
}

.project-card .tech-stack {
    color: var(--secondary-color);
    font-weight: 600;
    font-size: 0.85rem;
    margin-bottom: 0.8rem;
}

.project-card p {
    margin-bottom: 0.8rem;
    line-height: 1.6;
    font-size: 0.95rem;
}

.project-card ul {
    list-style: none;
    margin: 1rem 0;
    padding-left: 0;
}

.project-card li {
    padding-left: 25px;
    margin-bottom: 0.8rem;
    position: relative;
    line-height: 1.6;
}

.project-card li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: bold;
    font-size: 1.2rem;
}

.project-link {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 10px 20px;
    border-radius: 5px;
    font-weight: 600;
    margin-top: 1rem;
    transition: all 0.3s ease;
}

.project-link:hover {
    background: var(--secondary-color);
    transform: translateX(3px);
}

#contact {
    background: var(--muted-surface);
}

.contact-actions {
    display: grid;
    gap: 1rem;
    grid-template-columns: 1fr;
    margin: 0 auto;
    max-width: 900px;
}

.contact-action {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--secondary-color);
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    color: var(--text-dark);
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    padding: 1.2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}

.contact-action:hover {
    border-color: var(--secondary-color);
    color: var(--text-dark);
    transform: translateY(-4px);
    box-shadow: 0 8px 16px rgba(47, 52, 58, 0.14);
}

.contact-action-label {
    color: var(--primary-color);
    font-size: 1rem;
    font-weight: 700;
}

.contact-form {
    max-width: 900px;
    margin: 0 auto;
    background: var(--surface-color);
    padding: 1.8rem;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.form-group {
    margin-bottom: 1.2rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.4rem;
    font-weight: 600;
    color: var(--primary-color);
    font-size: 0.95rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-family: inherit;
    font-size: 0.95rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 5px rgba(107, 114, 128, 0.28);
}

.submit-btn {
    background: var(--primary-color);
    color: white;
    padding: 11px 28px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    width: 100%;
}

.submit-btn:hover {
    background: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(47, 52, 58, 0.24);
}

footer {
    background: var(--primary-color);
    color: var(--text-light);
    text-align: center;
    padding: 2rem;
    margin-top: 3rem;
}

footer a {
    color: #f1f3f5;
    font-weight: 600;
}

footer a:hover {
    text-decoration: underline;
    color: white;
}

.hero-section {
    scroll-margin-top: 120px;
}

.services-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

@media (min-width: 769px) {
    .services-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }
}

@media (min-width: 481px) and (max-width: 768px) {
    .services-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }

    .header-container {
        padding: 12px 14px;
        gap: 10px;
    }

    .header-content {
        gap: 10px;
        flex: 1 1 calc(100% - 104px);
    }

    header img {
        width: 58px;
        height: 58px;
        border-width: 2px;
    }

    .header-text h1 {
        font-size: 1.1rem;
    }

    .header-text .tagline {
        font-size: 0.75rem;
        line-height: 1.35;
    }

    .cv-link {
        width: 38px;
        height: 38px;
        margin-right: 2px;
    }

    .menu-toggle {
        font-size: 1.6rem;
        padding: 4px;
    }

    .nav-menu ul {
        gap: 4px;
        padding: 12px 0 4px;
    }

    .nav-menu ul li,
    .nav-menu ul li a {
        width: 100%;
    }

    .nav-menu ul li a {
        padding: 9px 0;
    }

    section {
        padding: 1.6rem 1rem;
        scroll-margin-top: 92px;
    }

    section h2 {
        font-size: 1.45rem;
        margin-bottom: 1.2rem;
    }

    .contact-info,
    .skill-category,
    .education-card,
    .certificate-card,
    .experience-card,
    .project-card,
    .contact-form {
        padding: 1.15rem;
    }

    .contact-info p {
        align-items: flex-start;
        gap: 8px;
        overflow-wrap: anywhere;
    }

    .skill-tag {
        font-size: 0.78rem;
        padding: 5px 10px;
    }

    .project-link,
    .submit-btn {
        width: 100%;
        text-align: center;
    }

    footer {
        padding: 2rem 1rem;
    }
}

@media (min-width: 481px) and (max-width: 768px) {
    .header-container {
        gap: 12px;
    }

    .header-content {
        flex: 1 1 calc(100% - 112px);
    }

    section {
        padding: 2rem 1.5rem;
        scroll-margin-top: 108px;
    }

    .skills-grid,
    .education-grid,
    .certificates-grid,
    .project-grid {
        grid-template-columns: 1fr;
    }
}

@media (min-width: 769px) {
    html {
        font-size: 15px;
    }

    .header-container {
        padding: 18px 35px;
        flex-wrap: nowrap;
        gap: 18px;
    }

    header img {
        width: 95px;
        height: 95px;
    }

    .header-content {
        flex: 0 1 auto;
    }

    .cv-link {
        order: 3;
        margin-right: 0;
    }

    .nav-menu {
        width: auto;
        order: 2;
        margin-left: auto;
    }

    .nav-menu ul {
        display: flex;
        flex-direction: row;
        border: none;
        padding: 0;
        margin: 0;
        gap: 16px;
        align-items: center;
    }

    .nav-menu ul li a {
        white-space: nowrap;
    }

    .menu-toggle {
        display: none;
    }

    section {
        padding: 2.5rem 2.5rem;
    }

    .about-content {
        grid-template-columns: 1.5fr 1fr;
        gap: 2.5rem;
    }

    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }

    .contact-actions {
        grid-template-columns: repeat(3, 1fr);
    }

    .education-grid {
        grid-template-columns: 1fr 1fr;
        gap: 1.5rem;
    }

    .certificates-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }

    .project-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }
}

@media (min-width: 769px) and (max-width: 900px) {
    .header-container {
        flex-wrap: wrap;
    }

    .header-content {
        flex: 1;
    }

    .nav-menu {
        width: 100%;
        order: 4;
        margin-left: 0;
    }

    .nav-menu ul {
        justify-content: center;
        flex-wrap: wrap;
        gap: 10px 18px;
        padding-top: 14px;
        border-top: 1px solid rgba(255, 255, 255, 0.25);
    }
}

@media (min-width: 1025px) {
    html {
        font-size: 15px;
    }

    .header-container {
        padding: 20px 50px;
    }

    .nav-menu ul {
        gap: 25px;
    }

    header img {
        width: 110px;
        height: 110px;
    }

    section {
        padding: 3rem 3.5rem;
    }

    section h2 {
        font-size: 2rem;
        margin-bottom: 2rem;
    }

    .about-content {
        grid-template-columns: 1.8fr 1fr;
        gap: 3rem;
    }

    .skills-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }

    .project-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 2rem;
    }

    .certificates-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }

    .contact-form {
        max-width: 900px;
    }

    .project-card {
        padding: 2.2rem;
    }
}