:root {
    /* Material 3 Dark Theme Tokens */
    --md-sys-color-background: #141218;
    --md-sys-color-on-background: #E6E0E9;
    --md-sys-color-surface: #141218;
    --md-sys-color-surface-container: #1D1B20;
    --md-sys-color-surface-container-high: #2B2930;
    --md-sys-color-surface-container-highest: #36343B;
    --md-sys-color-on-surface: #E6E0E9;
    --md-sys-color-on-surface-variant: #CAC4D0;
    --md-sys-color-primary: #D0BCFF;
    --md-sys-color-on-primary: #381E72;
    --md-sys-color-primary-container: #4F378B;
    --md-sys-color-on-primary-container: #EADDFF;
    --md-sys-color-secondary-container: #4A4458;
    --md-sys-color-on-secondary-container: #E8DEF8;
    --md-sys-color-outline: #938F99;
    --md-sys-color-outline-variant: #49454F;

    /* Elevation */
    --md-sys-elevation-1: 0px 1px 3px 1px rgba(0, 0, 0, 0.15), 0px 1px 2px 0px rgba(0, 0, 0, 0.3);
    --md-sys-elevation-2: 0px 2px 6px 2px rgba(0, 0, 0, 0.15), 0px 1px 2px 0px rgba(0, 0, 0, 0.3);

    /* Expressive Shapes */
    --md-sys-shape-corner-extra-large: 28px;
    --md-sys-shape-corner-large: 16px;
    --md-sys-shape-corner-full: 9999px;
}

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

body {
    font-family: 'Roboto', 'Inter', -apple-system, sans-serif;
    background-color: var(--md-sys-color-background);
    color: var(--md-sys-color-on-background);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

/* Material 3 TopAppBar */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    height: 64px;
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--md-sys-color-surface);
    color: var(--md-sys-color-on-surface);
    z-index: 1000;
    transition: background-color 0.3s;
    border-bottom: 1px solid var(--md-sys-color-surface-container-highest);
}

.logo {
    display: flex;
    align-items: center;
    font-weight: 500;
    font-size: 22px; /* M3 Title Large */
    letter-spacing: 0px;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 24px;
}

.nav-links a {
    color: var(--md-sys-color-on-surface-variant);
    text-decoration: none;
    font-weight: 500;
    font-size: 14px; /* M3 Label Large */
    letter-spacing: 0.1px;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: var(--md-sys-color-on-surface);
}

main {
    margin-top: 64px; /* Account for navbar */
    padding-bottom: 80px;
}

/* Expressive Hero Section */
.hero {
    padding: 100px 24px 60px;
    text-align: center;
    max-width: 840px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 57px; /* M3 Display Large */
    line-height: 64px;
    letter-spacing: -0.25px;
    font-weight: 400;
    color: var(--md-sys-color-primary);
    margin-bottom: 24px;
}

.hero p {
    font-size: 16px; /* M3 Body Large */
    letter-spacing: 0.5px;
    color: var(--md-sys-color-on-surface-variant);
    margin-bottom: 40px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 16px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0 24px;
    height: 40px;
    border-radius: var(--md-sys-shape-corner-full);
    text-decoration: none;
    font-weight: 500;
    font-size: 14px;
    letter-spacing: 0.1px;
    transition: background-color 0.2s, box-shadow 0.2s;
    border: none;
    cursor: pointer;
}

/* M3 Filled Button */
.btn.primary {
    background-color: var(--md-sys-color-primary);
    color: var(--md-sys-color-on-primary);
}
.btn.primary:hover {
    background-color: #EADDFF; /* Hover state tint */
    box-shadow: var(--md-sys-elevation-1);
}

/* M3 Tonal Button */
.btn.secondary {
    background-color: var(--md-sys-color-secondary-container);
    color: var(--md-sys-color-on-secondary-container);
}
.btn.secondary:hover {
    background-color: #5D566D; /* Hover state tint */
}

.features-section, .guides-section {
    padding: 40px 24px;
    max-width: 1200px;
    margin: 0 auto;
}

h2 {
    font-size: 32px; /* M3 Headline Medium */
    font-weight: 400;
    line-height: 40px;
    color: var(--md-sys-color-on-surface);
    margin-bottom: 8px;
    text-align: left;
}

.section-subtitle {
    font-size: 14px;
    color: var(--md-sys-color-on-surface-variant);
    margin-bottom: 32px;
}

/* M3 Elevated Cards */
.feature-grid, .guides-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 16px;
}

.feature-card, .guide-card {
    background-color: var(--md-sys-color-surface-container);
    border-radius: var(--md-sys-shape-corner-extra-large);
    padding: 24px;
    transition: background-color 0.2s, box-shadow 0.2s;
    text-decoration: none;
    display: block;
}

.feature-card:hover, .guide-card:hover {
    background-color: var(--md-sys-color-surface-container-high);
    box-shadow: var(--md-sys-elevation-1);
}

.icon {
    font-size: 24px;
    margin-bottom: 16px;
    color: var(--md-sys-color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    background: var(--md-sys-color-primary-container);
    border-radius: 12px;
}

.feature-card h3, .guide-card h3 {
    font-size: 22px; /* M3 Title Large */
    font-weight: 400;
    color: var(--md-sys-color-on-surface);
    margin-bottom: 8px;
}

.feature-card p, .guide-card p {
    font-size: 14px; /* M3 Body Medium */
    color: var(--md-sys-color-on-surface-variant);
    letter-spacing: 0.25px;
}

.guide-card {
    border: 1px solid var(--md-sys-color-outline-variant);
    background-color: transparent;
}
.guide-card:hover {
    background-color: var(--md-sys-color-surface-container);
    border-color: var(--md-sys-color-outline);
}
.guide-card h3 {
    color: var(--md-sys-color-primary);
}

footer {
    text-align: center;
    padding: 24px;
    background-color: var(--md-sys-color-surface-container);
    color: var(--md-sys-color-on-surface-variant);
    font-size: 12px;
}

@media (max-width: 768px) {
    .hero h1 { 
        font-size: 45px; /* M3 Display Medium */
        line-height: 52px;
    }
    .nav-links { display: none; }
}