/* ===== CSS Variables ===== */
:root {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #1c2128;
    --text-primary: #f0f6fc;
    --text-secondary: #8b949e;
    --text-muted: #6e7681;
    --accent: #f57c00;
    --accent-hover: #ff9800;
    --accent-glow: rgba(245, 124, 0, 0.15);
    --border-color: #30363d;
    --success: #3fb950;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

/* ===== Reset & Base ===== */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 16px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

h1,
h2,
h3 {
    line-height: 1.2;
    font-weight: 600;
}

h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
}

h2 {
    font-size: clamp(1.5rem, 3vw, 2.25rem);
}

h3 {
    font-size: 1.125rem;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

ul {
    list-style: none;
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 14px 28px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent), #e65100);
    color: #fff;
    box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--accent-hover), var(--accent));
    transform: translateY(-2px);
    box-shadow: 0 6px 30px var(--accent-glow);
    color: #fff;
}

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

.btn-secondary:hover {
    border-color: var(--accent);
    background: var(--accent-glow);
    color: var(--text-primary);
}

.btn-large {
    padding: 18px 40px;
    font-size: 1.125rem;
}

.cta-group {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

/* ===== Hero Section ===== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: 80px 0;
    overflow: hidden;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 2;
}

.hero-text h1 {
    margin-bottom: 24px;
}

.hero-text .accent {
    color: var(--accent);
    font-style: italic;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 16px;
    max-width: 540px;
}

.tagline {
    color: var(--accent);
    font-weight: 600;
    font-size: 1.1rem;
    margin-bottom: 32px;
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.book-mockup {
    position: relative;
    transform: perspective(1000px) rotateY(-8deg) rotateX(2deg);
    transition: transform 0.4s ease;
}

.book-mockup:hover {
    transform: perspective(1000px) rotateY(-2deg) rotateX(0deg);
}

.book-mockup img {
    max-width: 400px;
    width: 100%;
    border-radius: 8px;
    box-shadow:
        0 25px 50px -12px rgba(0, 0, 0, 0.5),
        0 0 60px var(--accent-glow);
}

.hero-bg-grid {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image:
        linear-gradient(rgba(245, 124, 0, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(245, 124, 0, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    pointer-events: none;
}

/* ===== Section Styles ===== */
section {
    padding: 100px 0;
}

section:nth-child(even) {
    background-color: var(--bg-secondary);
}

section h2 {
    text-align: center;
    margin-bottom: 16px;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 48px;
    font-size: 1.1rem;
}

/* ===== Problem Section ===== */
.problem h2 {
    margin-bottom: 48px;
}

.problem-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 32px;
}

.problem-card {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 32px;
    transition: border-color 0.2s ease;
}

.problem-card:hover {
    border-color: var(--accent);
}

.problem-icon {
    color: var(--accent);
    margin-bottom: 16px;
}

.problem-card h3 {
    margin-bottom: 12px;
}

.problem-card p {
    color: var(--text-secondary);
}

/* ===== Solution Section ===== */
.solution-content {
    max-width: 700px;
    margin: 48px auto 0;
}

.solution-list li {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 16px 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 1.1rem;
}

.solution-list li:last-child {
    border-bottom: none;
}

.check-icon {
    color: var(--success);
    font-weight: 700;
    font-size: 1.25rem;
}

/* ===== What's Inside Section ===== */
.content-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.content-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 28px;
    transition: all 0.2s ease;
}

.content-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
}

.card-icon {
    color: var(--accent);
    margin-bottom: 16px;
}

.content-card h3 {
    margin-bottom: 8px;
}

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

/* ===== Audience Section ===== */
.audience-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    max-width: 900px;
    margin: 0 auto;
}

.audience-for h2 {
    text-align: left;
    margin-bottom: 24px;
}

.audience-for ul li,
.audience-not ul li {
    padding: 10px 0;
    padding-left: 24px;
    position: relative;
}

.audience-for ul li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent);
}

.audience-not {
    background: var(--bg-tertiary);
    border-radius: 12px;
    padding: 32px;
    border: 1px solid var(--border-color);
}

.audience-not h3 {
    margin-bottom: 20px;
    color: var(--text-secondary);
}

.audience-not ul li::before {
    content: '✕';
    position: absolute;
    left: 0;
    color: var(--text-muted);
}

/* ===== Preview Section ===== */
.preview-showcase {
    display: flex;
    justify-content: center;
    gap: 32px;
    flex-wrap: wrap;
}

.preview-card {
    max-width: 500px;
}

.preview-placeholder {
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.4);
}

.preview-placeholder img {
    width: 100%;
    display: block;
}

.preview-caption {
    text-align: center;
    color: var(--text-secondary);
    margin-top: 16px;
    font-size: 0.9rem;
}

/* ===== Authority Section ===== */
.authority {
    text-align: center;
}

.authority-logo {
    margin-bottom: 32px;
}

.authority-logo img {
    max-width: 180px;
    border-radius: 50%;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
}

.authority-text {
    max-width: 700px;
    margin: 32px auto 24px;
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.authority-brand {
    color: var(--accent);
    font-weight: 600;
    font-size: 1.25rem;
}

/* ===== FAQ Section ===== */
.faq-list {
    max-width: 700px;
    margin: 48px auto 0;
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
}

.faq-question {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    text-align: left;
    font-family: inherit;
}

.faq-question:hover {
    color: var(--accent);
}

.faq-icon {
    font-size: 1.5rem;
    color: var(--accent);
    transition: transform 0.2s ease;
}

.faq-item.active .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 200px;
}

.faq-answer p {
    padding-bottom: 20px;
    color: var(--text-secondary);
}

/* ===== Final CTA Section ===== */
.final-cta {
    text-align: center;
    background: linear-gradient(180deg, var(--bg-secondary), var(--bg-primary));
    padding: 120px 0;
}

.final-cta h2 {
    max-width: 600px;
    margin: 0 auto 32px;
}

.cta-note {
    margin-top: 16px;
    color: var(--text-secondary);
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    padding: 48px 0;
    text-align: center;
}

.footer-content {
    margin-bottom: 24px;
}

.footer-logo {
    max-width: 80px;
    border-radius: 50%;
    margin-bottom: 16px;
}

.footer-title {
    font-weight: 600;
    margin-bottom: 4px;
}

.footer-brand {
    color: var(--accent);
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 32px;
    margin-bottom: 24px;
}

.footer-links a {
    color: var(--text-secondary);
}

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

.footer-copyright {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-text {
        order: 1;
    }

    .hero-image {
        order: 0;
        margin-bottom: 40px;
    }

    .book-mockup {
        transform: none;
    }

    .book-mockup:hover {
        transform: none;
    }

    .subtitle {
        margin: 0 auto 16px;
    }

    .cta-group {
        justify-content: center;
    }

    .audience-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .audience-for h2 {
        text-align: center;
    }
}

@media (max-width: 600px) {
    section {
        padding: 60px 0;
    }

    .btn {
        width: 100%;
    }

    .cta-group {
        flex-direction: column;
    }

    .book-mockup img {
        max-width: 280px;
    }

    .footer-links {
        flex-direction: column;
        gap: 16px;
    }
}