:root {
    --bg-color: #0a0a0a;
    --card-bg: #121212;
    --card-border: #222222;
    --primary-red: #8B0000;
    --hover-red: #a30000;
    --text-color: #e0e0e0;
    --text-white: #ffffff;
    --text-muted: #888888;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Plus Jakarta Sans', sans-serif;
}

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

.header {
    background-color: rgba(10, 10, 10, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--card-border);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
}

.nav-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-white);
    text-decoration: none;
}

.logo span {
    color: var(--primary-red);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 1.5rem;
}

.nav-item {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

.nav-item:hover, .nav-item.active {
    color: var(--text-white);
}

.mobile-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-white);
    font-size: 1.5rem;
    cursor: pointer;
}

.fade-in-up {
    animation: fadeInUp 0.6s ease forwards;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.main-content {
    padding-top: 100px;
    padding-bottom: 50px;
    min-height: 100vh;
}

.page-section {
    display: none;
}

.page-section.active {
    display: block;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-red), transparent);
}

.card-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.card-header h2 {
    color: var(--text-white);
    font-size: 1.6rem;
}

.icon-accent {
    color: var(--primary-red);
}

.card-body p {
    margin-bottom: 1rem;
    color: var(--text-color);
}

.card-body strong {
    color: var(--text-white);
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1.5rem;
}

.badge {
    background: rgba(139, 0, 0, 0.15);
    border: 1px solid var(--primary-red);
    color: var(--text-white);
    padding: 0.4rem 0.8rem;
    border-radius: 6px;
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.topic-navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 1.5rem;
    gap: 1rem;
}

.btn-nav {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text-white);
    padding: 0.8rem 1.2rem;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
    font-weight: 600;
}

.btn-nav:hover {
    border-color: var(--primary-red);
    background: rgba(139, 0, 0, 0.2);
}

.topic-list {
    list-style: none;
    margin-top: 1rem;
}

.topic-list li {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: 0.75rem;
}

.topic-list li::before {
    content: '•';
    color: var(--primary-red);
    font-weight: bold;
    font-size: 1.2rem;
    position: absolute;
    left: 0;
    top: -2px;
}

@media (max-width: 768px) {
    .mobile-toggle {
        display: block;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--card-bg);
        flex-direction: column;
        padding: 1.5rem;
        border-bottom: 1px solid var(--card-border);
    }

    .nav-links.active {
        display: flex;
    }

    .topic-navigation {
        flex-direction: column;
    }

    .btn-nav {
        justify-content: center;
        width: 100%;
    }
}