:root {
    --primary: #2C00FA;
    --accent-red: #FA2400;
    --accent-yellow: #FADD00;
    --accent-mint: #00FA8C;
    --accent-olive: #A59837;
    --accent-brown: #7A463D;
    
    --bg-dark: #0a0a0c;
    --bg-card: rgba(255, 255, 255, 0.05);
    --text-main: #ffffff;
    --text-muted: #b0b0b0;
    
    --glass-bg: rgba(255, 255, 255, 0.03);
    --glass-border: rgba(255, 255, 255, 0.1);
    
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

/* Header & Nav */
header {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(10, 10, 12, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--glass-border);
    padding: 0.8rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.site-title {
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    background: linear-gradient(90deg, var(--accent-mint), var(--accent-yellow));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    max-width: 60%;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 1rem;
}

nav a {
    text-decoration: none;
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 500;
    transition: var(--transition);
}

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

/* Hero Section */
.hero {
    height: 60vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    background: radial-gradient(circle at top right, rgba(44, 0, 250, 0.1), transparent),
                radial-gradient(circle at bottom left, rgba(0, 250, 140, 0.05), transparent);
    padding: 2rem;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    font-weight: 800;
}

.btn-download {
    padding: 0.8rem 2rem;
    background: var(--accent-mint);
    color: #000;
    text-decoration: none;
    border-radius: 50px;
    font-weight: 700;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    display: inline-block;
    margin-top: 1rem;
}

.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(0, 250, 140, 0.3);
}

/* Chapters Grid */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.chapters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.chapter-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 2rem;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

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

.chapter-number {
    font-size: 3rem;
    font-weight: 900;
    color: rgba(255, 255, 255, 0.05);
    position: absolute;
    top: 10px;
    right: 20px;
}

.chapter-card h3 {
    color: var(--accent-mint);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

.chapter-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Practice Section */
.practice-link-section {
    text-align: center;
    padding: 4rem 2rem;
    background: linear-gradient(to bottom, transparent, rgba(44, 0, 250, 0.05));
}

.btn-practice {
    padding: 1rem 3rem;
    background: transparent;
    color: var(--accent-yellow);
    border: 2px solid var(--accent-yellow);
    text-decoration: none;
    border-radius: 50px;
    font-weight: 700;
    transition: var(--transition);
}

.btn-practice:hover {
    background: var(--accent-yellow);
    color: #000;
}

/* Practice Page Specifics */
.qa-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 6rem 2rem;
}

.qa-item {
    background: var(--glass-bg);
    border-radius: 15px;
    margin-bottom: 1.5rem;
    padding: 1.5rem;
    border-left: 4px solid var(--accent-blue);
}

.qa-question {
    font-weight: 700;
    margin-bottom: 1rem;
    display: block;
}

.qa-answer {
    color: var(--accent-mint);
    font-style: italic;
    border-top: 1px solid var(--glass-border);
    padding-top: 1rem;
}

/* Footer */
footer {
    padding: 2rem;
    text-align: center;
    border-top: 1px solid var(--glass-border);
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    header {
        flex-direction: column;
        padding: 1rem 0.5rem;
        position: relative; /* Unfix on mobile to save space if needed, or keep fixed */
    }
    
    .site-title {
        max-width: 100%;
        text-align: center;
        font-size: 0.75rem;
        margin-bottom: 0.5rem;
    }
    
    nav ul {
        gap: 0.6rem;
        flex-wrap: wrap;
        justify-content: center;
    }

    nav a {
        font-size: 0.7rem;
    }
    
    .hero {
        height: auto;
        padding: 5rem 1rem 3rem 1rem;
    }

    .hero h1 {
        font-size: 1.8rem;
    }

    .hero p {
        font-size: 0.9rem;
    }
    
    .container {
        padding: 2rem 1rem;
    }

    .container h2 {
        font-size: 1.5rem !important;
    }

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

    .chapter-card {
        padding: 1.5rem;
    }
}