@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Outfit:wght@400;500;600;700;800&display=swap');

:root {
    --bg-main: #f8fafc;
    --bg-card: rgba(255, 255, 255, 0.85);
    --bg-card-hover: rgba(255, 255, 255, 1);
    --border-color: rgba(15, 23, 42, 0.08);
    --border-hover: rgba(37, 99, 235, 0.4);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --primary: #2563eb;
    --primary-glow: rgba(37, 99, 235, 0.08);
    --secondary: #0891b2;
    --accent: #10b981;
    --orange: #f97316;
    --orange-hover: #ea580c;
    --orange-glow: rgba(249, 115, 22, 0.15);
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --font-sans: 'Inter', sans-serif;
    --font-heading: 'Outfit', sans-serif;
    --max-width: 1200px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

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

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-main);
}
::-webkit-scrollbar-thumb {
    background: rgba(0, 0, 0, 0.1);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* Typography */
h1, h2, h3, h4 {
    font-family: var(--font-heading);
    font-weight: 700;
    letter-spacing: -0.02em;
}

a {
    color: inherit;
    text-decoration: none;
    transition: color var(--transition-fast);
}

/* Header & Navigation */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(248, 250, 252, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1.25rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--text-primary) 30%, var(--primary) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo span {
    color: var(--secondary);
    -webkit-text-fill-color: initial;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
    align-items: center;
}

.nav-links a {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.nav-links a:hover {
    color: var(--text-primary);
}

.nav-links a.btn {
    color: white;
}

.nav-links a.btn:hover {
    color: white;
}

/* Hero Section */
.hero {
    position: relative;
    padding: 9rem 2rem 5rem;
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 4rem;
    align-items: center;
}

.hero-glow {
    position: absolute;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, var(--primary-glow) 0%, transparent 70%);
    top: 15%;
    right: 5%;
    pointer-events: none;
    z-index: -1;
}

.hero-content h1 {
    font-size: 3.5rem;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, var(--text-primary) 40%, #1e3a8a 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-content p {
    font-size: 1.15rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    max-width: 540px;
}

.hero-btns {
    display: flex;
    gap: 1rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all var(--transition-fast);
    cursor: pointer;
}

.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
}

.btn-primary:hover {
    background: #1d4ed8;
    box-shadow: 0 0 20px rgba(37, 99, 235, 0.2);
}

.btn-orange {
    background: var(--orange);
    color: white;
    border: none;
}

.btn-orange:hover {
    background: var(--orange-hover);
    box-shadow: 0 0 20px var(--orange-glow);
}

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

.btn-secondary:hover {
    background: rgba(15, 23, 42, 0.04);
    border-color: var(--text-muted);
}

/* Book Cover Presentation */
.hero-book-wrap {
    perspective: 1000px;
    display: flex;
    justify-content: center;
}

.book-card {
    width: 280px;
    height: 400px;
    background: linear-gradient(145deg, #1e293b, #0f172a);
    border-radius: 12px;
    box-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.1);
    transform: rotateY(-15deg) rotateX(10deg);
    transition: transform var(--transition-normal), box-shadow var(--transition-normal);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    padding: 2.5rem 2rem;
}

.book-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 15px;
    height: 100%;
    background: linear-gradient(to right, rgba(0,0,0,0.3) 0%, rgba(255,255,255,0.05) 50%, rgba(0,0,0,0.2) 100%);
    border-right: 1px solid rgba(255,255,255,0.1);
}

.book-card:hover {
    transform: rotateY(-5deg) rotateX(5deg) scale(1.02);
    box-shadow: 0 35px 60px -10px rgba(37, 99, 235, 0.2);
}

.book-card .author {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--secondary);
    font-weight: 600;
}

.book-card .title {
    font-family: var(--font-heading);
    font-size: 2.2rem;
    line-height: 1.1;
    color: white;
    margin-top: 1rem;
    font-weight: 800;
}

.book-card .subtitle {
    font-size: 0.95rem;
    color: #94a3b8;
    margin-top: 0.5rem;
}

.book-card .badge {
    align-self: flex-start;
    padding: 0.25rem 0.75rem;
    background: rgba(37, 99, 235, 0.2);
    border: 1px solid var(--primary);
    color: #60a5fa;
    font-size: 0.75rem;
    border-radius: 99px;
    font-weight: 600;
}

/* Stats Section */
.stats {
    max-width: var(--max-width);
    margin: 3rem auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.stat-item {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    padding: 1.5rem 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.02), 0 2px 4px -1px rgba(0, 0, 0, 0.01);
    transition: all var(--transition-fast);
}

.stat-item:hover {
    border-color: var(--border-hover);
    transform: translateY(-4px);
}

.stat-number {
    font-family: var(--font-heading);
    font-size: 2.25rem;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 0.25rem;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* Section Header */
.section-header {
    text-align: center;
    max-width: 600px;
    margin: 6rem auto 3rem;
    padding: 0 2rem;
}

.section-header h2 {
    font-size: 2.25rem;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--text-primary) 50%, var(--text-muted) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.section-header p {
    color: var(--text-secondary);
}

/* Interactive Book Content Section */
.toc-section {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

/* Layout for TOC & Details Panel */
.toc-layout {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 3rem;
    align-items: start;
    margin-bottom: 6rem;
}

.parts-container {
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

.part-card {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.02);
}

.part-title {
    font-size: 1.1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--secondary);
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.75rem;
}

.chapters-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.chapter-item {
    background: rgba(15, 23, 42, 0.02);
    border: 1px solid var(--border-color);
    padding: 1rem 1.25rem;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: all var(--transition-fast);
}

.chapter-item:hover, .chapter-item.active {
    background: rgba(37, 99, 235, 0.05);
    border-color: var(--primary);
    transform: translateX(4px);
}

.chapter-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.chapter-num {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 1rem;
    color: var(--text-muted);
    min-width: 25px;
}

.chapter-item:hover .chapter-num, .chapter-item.active .chapter-num {
    color: var(--secondary);
}

.chapter-title {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-primary);
}

.chapter-chevron {
    color: var(--text-muted);
    font-size: 0.8rem;
    transition: transform var(--transition-fast);
}

.chapter-item:hover .chapter-chevron, .chapter-item.active .chapter-chevron {
    color: var(--primary);
    transform: translateX(2px);
}

/* Detail Panel Styling */
.details-panel {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2.5rem;
    position: sticky;
    top: 7rem;
    min-height: 450px;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.04);
}

.panel-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 350px;
    text-align: center;
    color: var(--text-muted);
    gap: 1rem;
}

.panel-placeholder svg {
    color: var(--border-color);
}

.detail-num {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--secondary);
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.detail-title {
    font-size: 1.75rem;
    line-height: 1.2;
    margin-bottom: 1.5rem;
}

.detail-desc {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 0.95rem;
}

.detail-section-title {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
    font-weight: 700;
}

.objectives-list {
    list-style: none;
    margin-bottom: 2rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.objectives-list li {
    font-size: 0.9rem;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
}

.objectives-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--primary);
}

.case-study-box {
    background: rgba(37, 99, 235, 0.04);
    border: 1px dashed rgba(37, 99, 235, 0.3);
    border-radius: 8px;
    padding: 1.25rem;
}

.case-study-title {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.case-study-desc {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Resources Section */
.resources-grid {
    max-width: var(--max-width);
    margin: 0 auto 6rem;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.resource-card {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    padding: 2.25rem 2rem;
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.02);
    transition: all var(--transition-fast);
}

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

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

.resource-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
}

.resource-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
}

.resource-link {
    align-self: flex-start;
    color: var(--primary);
    font-weight: 600;
    font-size: 0.9rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.resource-link:hover {
    color: var(--secondary);
}

/* Badge specific style */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: rgba(37, 99, 235, 0.08);
    border: 1px solid var(--primary);
    color: var(--primary);
    font-size: 0.75rem;
    border-radius: 99px;
    font-weight: 600;
}

/* Author Section */
.author-section {
    max-width: var(--max-width);
    margin: 0 auto 6rem;
    padding: 0 2rem;
}

.author-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 3rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.02);
    display: grid;
    grid-template-columns: 0.6fr 1.4fr;
    gap: 3rem;
    align-items: center;
}

.author-image-wrap {
    display: flex;
    justify-content: center;
}

.author-avatar {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    padding: 4px;
    box-shadow: 0 10px 25px rgba(37, 99, 235, 0.1);
}

.author-avatar-img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background: #1e293b;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: white;
    font-family: var(--font-heading);
    font-weight: 700;
}

.author-info h3 {
    font-size: 1.75rem;
    margin-bottom: 0.5rem;
}

.author-role {
    color: var(--secondary);
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 1.25rem;
}

.author-bio {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1.5rem;
}

/* Contact / Newsletter Section */
.contact-section {
    max-width: 600px;
    margin: 0 auto 8rem;
    padding: 0 2rem;
    text-align: center;
}

/* Resource Card Header (Flex for icon next to title) */
.resource-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.resource-header h3 {
    margin-bottom: 0;
}

.resource-icon {
    color: var(--primary);
    display: flex;
    align-items: center;
}

.resource-item-link {
    color: var(--primary);
    font-weight: 500;
    text-decoration: none;
    border-bottom: 1px dashed var(--primary);
    transition: all var(--transition-fast);
}

.resource-item-link:hover {
    color: var(--secondary);
    border-color: var(--secondary);
}

.resource-item-disabled {
    color: var(--text-muted);
    font-weight: 500;
    cursor: default;
}

.badge-soon {
    font-size: 0.7rem;
    padding: 0.15rem 0.4rem;
    background: rgba(148, 163, 184, 0.08);
    border: 1px solid rgba(148, 163, 184, 0.15);
    color: var(--text-muted);
    border-radius: 4px;
    font-weight: 600;
    margin-left: 0.5rem;
    vertical-align: middle;
}

/* Button & Badge Utility Classes */
.btn-nav-amazon {
    padding: 0.5rem 1rem;
}

.badge-wrap {
    margin-bottom: 1rem;
}

.badge-promo {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--accent);
    color: #047857;
}

.hero-tagline {
    font-size: 1.4rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.book-card .title {
    font-size: 1.8rem;
}

.book-card .subtitle {
    font-size: 0.85rem;
    color: #cbd5e1;
    line-height: 1.3;
}

.book-card-footer {
    font-size: 0.75rem;
    color: #94a3b8;
    font-weight: 500;
}

.stats {
    grid-template-columns: repeat(4, 1fr);
}

.author-avatar {
    overflow: hidden;
    padding: 0;
}

.author-avatar-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: 50% 15%;
    border-radius: 50%;
}

.author-bio-muted {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
}

.btn-linkedin-follow {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.1rem;
    padding: 1rem 2rem;
}

/* Footer */
footer {
    border-top: 1px solid var(--border-color);
    padding: 4rem 2rem;
    background: #f1f5f9;
}

.footer-container {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-copy {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.resources-notice {
    display: inline-flex;
    align-items: center;
    gap: 0.65rem;
    background: rgba(37, 99, 235, 0.03);
    border: 1px solid rgba(37, 99, 235, 0.15);
    padding: 0.75rem 1.25rem;
    border-radius: 8px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 1.5rem auto 0;
    text-align: left;
}

.resources-notice .notice-icon {
    color: var(--primary);
    flex-shrink: 0;
}

/* Responsive adjustments */
@media (max-width: 1024px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 3rem;
    }
    
    .hero-content p {
        margin: 0 auto 2.5rem;
    }
    
    .hero-btns {
        justify-content: center;
    }
    
    .toc-layout {
        grid-template-columns: 1fr;
    }
    
    .details-panel {
        position: static;
        min-height: auto;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none; /* simple hidden navigation for mobile */
    }
    
    .resources-grid {
        grid-template-columns: 1fr;
    }
    
    .author-card {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .stats {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }
}