.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background-color: rgba(10, 10, 10, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
}

.header__container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--space-md);
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-md);
}

.header__logo {
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-md);
    color: var(--color-text-primary);
    letter-spacing: -0.02em;
    white-space: nowrap;
}

.nav {
    order: 3;
    width: 100%;
    overflow-x: auto;
}

.nav__list {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.nav__link {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--color-text-secondary);
    position: relative;
    padding: var(--space-xs) 0;
    white-space: nowrap;
}

    .nav__link::after {
        content: '';
        position: absolute;
        bottom: 0;
        left: 0;
        width: 100%;
        height: 2px;
        background-color: var(--color-accent);
        transform: scaleX(0);
        transform-origin: right;
        transition: transform var(--transition-smooth);
    }

    .nav__link:hover,
    .nav__link:focus-visible,
    .nav__link.is-active {
        color: var(--color-text-primary);
    }

        .nav__link:hover::after,
        .nav__link:focus-visible::after,
        .nav__link.is-active::after {
            transform: scaleX(1);
            transform-origin: left;
        }

.lang-switcher {
    order: 2;
    display: flex;
    gap: var(--space-xs);
}

.lang-switcher__link {
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-secondary);
    padding: var(--space-xs) var(--space-sm);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    transition: all var(--transition-fast);
}

    .lang-switcher__link:hover,
    .lang-switcher__link:focus-visible,
    .lang-switcher__link.is-active {
        color: var(--color-accent);
        border-color: var(--color-accent);
    }

.main {
    padding-top: 116px;
}

.section {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: var(--space-section) 0;
}

.section__container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-md);
}

.footer {
    padding: var(--space-xl) 0;
    background-color: var(--color-bg-surface);
    border-top: 1px solid var(--color-border);
}

.footer__container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-md);
}

.social {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-lg);
}

.social__link {
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-secondary);
    font-family: var(--font-family-mono);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: inline-block;
    transition: color var(--transition-fast), transform var(--transition-fast);
}

    .social__link:hover,
    .social__link:focus-visible {
        color: var(--color-accent);
        transform: translateY(-2px);
    }

.footer__copyright {
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    text-align: center;
    margin-top: var(--space-lg);
    font-family: var(--font-family-mono);
}

@media (min-width: 768px) {
    .header__container {
        flex-wrap: nowrap;
        padding: var(--space-md) var(--space-lg);
    }

    .nav {
        order: 2;
        width: auto;
        overflow-x: visible;
    }

    .lang-switcher {
        order: 3;
    }

    .nav__list {
        gap: var(--space-lg);
    }

    .main {
        padding-top: 73px;
    }

    .section__container {
        padding: 0 var(--space-lg);
    }

    .footer__container {
        padding: 0 var(--space-lg);
    }
}

.hero {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    max-width: 800px;
}

.hero__title {
    margin-bottom: var(--space-xs);
}

.hero__subtitle {
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-medium);
    color: var(--color-accent);
    font-family: var(--font-family-mono);
    margin-bottom: var(--space-md);
    line-height: 1.4;
}

.hero__description {
    font-size: var(--font-size-md);
    margin-bottom: var(--space-xl);
}

.hero__actions {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-bold);
    font-family: var(--font-family-mono);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: 4px;
    transition: all var(--transition-fast);
    will-change: transform;
}

.button--primary {
    background-color: var(--color-accent);
    color: var(--color-bg-base);
    border: 1px solid var(--color-accent);
}

    .button--primary:hover,
    .button--primary:focus-visible {
        background-color: var(--color-accent-hover);
        border-color: var(--color-accent-hover);
        transform: translateY(-2px);
    }

.button--secondary {
    background-color: transparent;
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

    .button--secondary:hover,
    .button--secondary:focus-visible {
        border-color: var(--color-text-primary);
        color: var(--color-text-primary);
        transform: translateY(-2px);
    }

@media (min-width: 768px) {
    .hero__subtitle {
        font-size: var(--font-size-lg);
    }

    .hero__description {
        font-size: var(--font-size-lg);
    }
}

.section-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-xxl);
    position: relative;
    padding-left: var(--space-md);
}

    .section-title::before {
        content: '';
        position: absolute;
        left: 0;
        top: 10%;
        height: 80%;
        width: 4px;
        background-color: var(--color-accent);
        border-radius: 2px;
    }

.timeline {
    position: relative;
    margin-left: var(--space-sm);
}

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

.timeline__item {
    position: relative;
    padding-left: var(--space-xl);
    padding-bottom: var(--space-xxl);
}

    .timeline__item:last-child {
        padding-bottom: 0;
    }

    .timeline__item::before {
        content: '';
        position: absolute;
        top: 0.4rem;
        left: -4px;
        width: 10px;
        height: 10px;
        border-radius: 50%;
        background-color: var(--color-bg-base);
        border: 2px solid var(--color-accent);
        transition: background-color var(--transition-fast), transform var(--transition-fast);
    }

    .timeline__item:hover::before {
        background-color: var(--color-accent);
        transform: scale(1.2);
    }

.timeline__header {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
    margin-bottom: var(--space-md);
}

.timeline__title {
    font-size: var(--font-size-lg);
    color: var(--color-text-primary);
}

.timeline__company {
    font-size: var(--font-size-md);
    color: var(--color-accent);
    font-family: var(--font-family-mono);
}

.timeline__date {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-style: italic;
}

.timeline__list {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.timeline__list-item {
    color: var(--color-text-secondary);
    position: relative;
    padding-left: var(--space-md);
    line-height: var(--line-height-body);
}

    .timeline__list-item::before {
        content: '▹';
        position: absolute;
        left: 0;
        top: 0;
        color: var(--color-accent);
        font-family: var(--font-family-mono);
    }

@media (min-width: 768px) {
    .timeline__header {
        flex-direction: row;
        align-items: baseline;
        flex-wrap: wrap;
        gap: var(--space-md);
    }

    .timeline__date {
        margin-left: auto;
    }
}

.skills-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-md);
}

.skill-card {
    background-color: var(--color-bg-surface);
    border: 1px solid var(--color-border);
    padding: var(--space-lg);
    border-radius: 4px;
    transition: border-color var(--transition-fast);
}

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

.skill-card__title {
    font-size: var(--font-size-md);
    color: var(--color-text-primary);
    margin-bottom: var(--space-md);
}

.skill-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.skill-card__tag {
    font-family: var(--font-family-mono);
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    background-color: var(--color-bg-base);
    border: 1px solid var(--color-border);
    padding: var(--space-xs) var(--space-sm);
    border-radius: 2px;
    cursor: default;
    transition: color var(--transition-fast), border-color var(--transition-fast);
}

    .skill-card__tag:hover {
        color: var(--color-accent);
        border-color: var(--color-accent);
    }

@media (min-width: 768px) {
    .skills-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-lg);
    }
}

.portfolio-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-lg);
}

.project-card {
    display: flex;
    flex-direction: column;
    background-color: var(--color-bg-surface);
    border: 1px solid var(--color-border);
    padding: var(--space-lg);
    border-radius: 4px;
    transition: border-color var(--transition-fast), transform var(--transition-fast);
}

    .project-card:hover {
        border-color: var(--color-accent);
        transform: translateY(-4px);
    }

.project-card__title {
    font-size: var(--font-size-lg);
    color: var(--color-text-primary);
    margin-bottom: var(--space-sm);
}

.project-card__description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-lg);
    flex-grow: 1;
}

.project-card__tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-bottom: var(--space-lg);
}

.project-card__tag {
    font-family: var(--font-family-mono);
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    background-color: var(--color-bg-base);
    border: 1px solid var(--color-border);
    padding: var(--space-xs) var(--space-sm);
    border-radius: 2px;
    cursor: default;
}

.project-card__links {
    margin-top: auto;
}

.project-card__link {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-secondary);
    font-family: var(--font-family-mono);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
}

    .project-card__link::after {
        content: '→';
        transition: transform var(--transition-fast);
    }

    .project-card__link:hover,
    .project-card__link:focus-visible {
        color: var(--color-accent);
    }

        .project-card__link:hover::after,
        .project-card__link:focus-visible::after {
            transform: translateX(4px);
        }

@media (min-width: 768px) {
    .portfolio-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .portfolio-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

.edu-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-lg);
}

.edu-item {
    background-color: transparent;
    border-left: 4px solid var(--color-border);
    padding-left: var(--space-md);
    transition: border-color var(--transition-fast), transform var(--transition-fast);
}

    .edu-item:hover {
        border-left-color: var(--color-accent);
        transform: translateX(4px);
    }

.edu-item__meta {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-xs);
}

.edu-item__type {
    font-family: var(--font-family-mono);
    font-size: var(--font-size-xs);
    color: var(--color-accent);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.edu-item__date {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-style: italic;
}

.edu-item__title {
    font-size: var(--font-size-md);
    color: var(--color-text-primary);
    margin-bottom: var(--space-xs);
}

.edu-item__specialty {
    display: block;
    font-size: var(--font-size-sm);
    color: var(--color-accent);
    font-family: var(--font-family-mono);
    margin-bottom: var(--space-xs);
}

.edu-item__issuer {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.edu-item__link {
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-secondary);
    font-family: var(--font-family-mono);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    margin-top: var(--space-sm);
}

    .edu-item__link::after {
        content: '↗';
        transition: transform var(--transition-fast);
    }

    .edu-item__link:hover,
    .edu-item__link:focus-visible {
        color: var(--color-accent);
    }

        .edu-item__link:hover::after,
        .edu-item__link:focus-visible::after {
            transform: translate(2px, -2px);
        }

@media (min-width: 1024px) {
    .edu-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.filter-nav {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-bottom: var(--space-xl);
    list-style: none;
}

.filter-btn {
    font-family: var(--font-family-mono);
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    background-color: transparent;
    border: 1px solid var(--color-border);
    padding: var(--space-xs) var(--space-sm);
    border-radius: 4px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.filter-btn:hover,
.filter-btn:focus-visible,
.filter-btn.is-active {
    color: var(--color-accent);
    border-color: var(--color-accent);
}

.edu-item.is-hidden {
    display: none;
}

.fade-in {
    animation: fadeIn 0.4s ease forwards;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}