:root {
    --bg-main: #121212;
    --bg-secondary: #1E1E1E;
    --accent-color: #10B981;
    --text-main: #E0E0E0;
    --text-secondary: #9CA3AF;
    --font-heading: 'Poppins', sans-serif;
    --font-body: 'Inter', sans-serif;
    --font-code: 'Fira Code', monospace;
}

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

html {
    scroll-behavior: smooth;
    overflow-x: hidden;
}

body {
    background-color: var(--bg-main);
    color: var(--text-main);
    font-family: var(--font-body);
    line-height: 1.6;
    overflow-x: hidden;
}

body.mobile-nav-open {
    overflow: hidden;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

.section-title {
    text-align: center;
    font-family: var(--font-heading);
    font-size: 2.5rem;
    margin-bottom: 60px;
    color: #FFFFFF;
}

section[id] {
    scroll-margin-top: 110px;
}

.site-header {
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(18, 18, 18, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #2a2a2a;
    transition: border-bottom-color 0.3s ease;
}

.site-header.scrolled {
    border-bottom-color: transparent;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-image {
    height: 60px;
    width: auto;
}

.main-nav {
    display: flex;
    align-items: center;
}

.main-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    margin-left: 30px;
    font-weight: 500;
    position: relative;
    transition: color 0.3s ease;
}

.main-nav a:hover {
    color: var(--accent-color);
}

.main-nav a::after {
    content: '';
    position: absolute;
    width: 100%;
    transform: scaleX(0);
    height: 2px;
    bottom: -6px;
    left: 0;
    background-color: var(--accent-color);
    transform-origin: center;
    transition: transform 0.3s ease-out;
}

.main-nav a:hover::after {
    transform: scaleX(1);
}

.mobile-nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-around;
    width: 30px;
    height: 25px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1010;
}

.hamburger-line {
    width: 30px;
    height: 3px;
    background-color: var(--text-main);
    border-radius: 3px;
    transition: all 0.3s linear;
}

.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 20px;
}

.hero-content h1 {
    font-family: var(--font-heading);
    font-size: 3.8rem;
    margin-bottom: 20px;
    background-image: linear-gradient(90deg,
            var(--accent-color),
            #38bdf8,
            var(--accent-color));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    background-size: 200% auto;
    animation: gradient-animation 5s linear infinite;
}

.hero-content p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 650px;
    margin: 0 auto;
}

.about-section {
    padding: 80px 0;
    background-color: var(--bg-secondary);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 50px;
    align-items: center;
}

.about-image img {
    max-width: 100%;
    border-radius: 12px;
}

.about-text h3 {
    font-family: var(--font-heading);
    font-size: 2rem;
    margin-bottom: 20px;
    color: #FFFFFF;
}

.about-text p {
    margin-bottom: 15px;
    color: var(--text-secondary);
}

.expertise-section {
    padding: 80px 0;
}

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

.expertise-card {
    background-color: var(--bg-secondary);
    padding: 30px;
    border-radius: 8px;
    border: 1px solid #2a2a2a;
    transition: transform 0.3s ease, border-color 0.3s ease;
}

.expertise-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-color);
}

.expertise-card h4 {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    margin-bottom: 15px;
    color: #FFFFFF;
}

.references-section {
    padding: 80px 0;
    background-color: var(--bg-secondary);
}

.reference-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.reference-card {
    background-color: var(--bg-main);
    border: 1px solid #2a2a2a;
    border-radius: 8px;
    padding: 25px;
    display: flex;
    flex-direction: column;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.reference-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 0 25px rgba(16, 185, 129, 0.2);
}

.reference-title {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    margin-bottom: 15px;
}

.reference-excerpt {
    color: var(--text-secondary);
    margin-bottom: 20px;
    flex-grow: 1;
}

.reference-tags .tag {
    background-color: rgba(16, 185, 129, 0.1);
    color: var(--accent-color);
    padding: 4px 10px;
    border-radius: 5px;
    font-family: var(--font-code);
    font-size: 0.8rem;
    margin-right: 8px;
    display: inline-block;
    margin-bottom: 5px;
}

.reference-links a {
    color: var(--text-main);
    text-decoration: none;
    font-weight: bold;
    border: 1px solid var(--accent-color);
    padding: 8px 15px;
    border-radius: 5px;
    transition: background-color 0.3s ease, color 0.3s ease;
    display: inline-block;
}

.reference-links a:hover {
    background-color: var(--accent-color);
    color: #FFFFFF;
}

.site-footer {
    background-color: var(--bg-main);
    padding: 60px 0 40px 0;
    text-align: center;
    border-top: 1px solid #2a2a2a;
}

.footer-logo {
    display: block;
    height: 50px;
    width: auto;
    margin: 0 auto 40px auto;
}

.footer-nav {
    margin-bottom: 40px;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 30px;
}

.footer-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-nav a:hover {
    color: var(--accent-color);
}

.social-links {
    margin-bottom: 40px;
}

.social-links a {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 44px;
    height: 44px;
    font-size: 1.2rem;
    color: var(--text-secondary);
    text-decoration: none;
    background-color: #2a2a2a;
    border-radius: 50%;
    margin: 0 10px;
    transition: background-color 0.3s ease, transform 0.3s ease;
}

.social-links a:hover {
    background-color: var(--accent-color);
    color: #FFFFFF;
    transform: translateY(-3px);
}

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

#lang-switcher {
    background-color: transparent;
    border: 1px solid var(--text-secondary);
    color: var(--text-secondary);
    padding: 6px 12px;
    border-radius: 5px;
    cursor: pointer;
    font-family: var(--font-body);
    font-weight: 500;
    margin-left: 30px;
    min-width: 45px;
    text-align: center;
    transition: all 0.3s ease;
}

#lang-switcher:hover {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    color: #FFFFFF;
}

@keyframes gradient-animation {
    0% {
        background-position: 0% 50%;
    }

    50% {
        background-position: 100% 50%;
    }

    100% {
        background-position: 0% 50%;
    }
}

@media (max-width: 820px) {
    .main-nav {
        position: fixed;
        top: 0;
        right: 0;
        width: 100%;
        height: 100vh;
        background-color: rgba(18, 18, 18, 0.95);
        backdrop-filter: blur(10px);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 40px;
        transform: translateX(100%);
        transition: transform 0.4s ease-in-out;
    }
    
    body.mobile-nav-open .main-nav {
        transform: translateX(0);
    }

    .main-nav a {
        margin-left: 0;
        font-size: 1.5rem;
    }

    #lang-switcher {
        margin-left: 0;
        padding: 10px 20px;
        font-size: 1.2rem;
    }

    .mobile-nav-toggle {
        display: flex;
    }
    
    .hero-content h1 {
        font-size: 2.5rem;
    }

    .about-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .about-image {
        margin-bottom: 30px;
        max-width: 200px;
        margin-left: auto;
        margin-right: auto;
    }
}