/* Critical CSS - Above the fold styles */
:root {
    --sky-50: #f0f9ff;
    --sky-100: #e0f2fe;
    --sky-500: #0ea5e9;
    --sky-600: #0284c7;
    --slate-50: #f8fafc;
    --slate-100: #f1f5f9;
    --slate-200: #e2e8f0;
    --slate-400: #94a3b8;
    --slate-500: #64748b;
    --slate-600: #475569;
    --slate-700: #334155;
    --slate-800: #1e293b;
    --slate-900: #0f172a;
    --green-50: #f0fdf4;
    --green-200: #bbf7d0;
    --green-500: #22c55e;
    --green-600: #16a34a;
    --green-800: #166534;
    --red-50: #fef2f2;
    --red-200: #fecaca;
    --red-600: #dc2626;
    --red-800: #991b1b;
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--slate-50);
    color: var(--slate-800);
    margin: 0;
    padding: 0;
    line-height: 1.6;
    overflow-x: hidden;
}

.hidden {
    display: none !important;
}

.scroll-smooth {
    scroll-behavior: smooth;
}

/* Container and Layout */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.grid {
    display: grid;
}

.flex {
    display: flex;
}

.items-center {
    align-items: center;
}

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

.justify-between {
    justify-content: space-between;
}

.text-center {
    text-align: center;
}

/* Typography */
.font-bold {
    font-weight: 700;
}

.font-extrabold {
    font-weight: 800;
}

.font-black {
    font-weight: 900;
}

.font-semibold {
    font-weight: 600;
}

.text-sm {
    font-size: 0.875rem;
    line-height: 1.25rem;
}

.text-lg {
    font-size: 1.125rem;
    line-height: 1.75rem;
}

.text-xl {
    font-size: 1.25rem;
    line-height: 1.75rem;
}

.text-2xl {
    font-size: 1.5rem;
    line-height: 2rem;
}

.text-4xl {
    font-size: 2.25rem;
    line-height: 2.5rem;
}

.text-5xl {
    font-size: 3rem;
    line-height: 1;
}

.text-6xl {
    font-size: 3.75rem;
    line-height: 1;
}

/* Colors */
.text-sky-600 {
    color: var(--sky-600);
}

.text-sky-500 {
    color: var(--sky-500);
}

.text-white {
    color: white;
}

.text-slate-400 {
    color: var(--slate-400);
}

.text-slate-500 {
    color: var(--slate-500);
}

.text-slate-600 {
    color: var(--slate-600);
}

.text-slate-700 {
    color: var(--slate-700);
}

.text-slate-800 {
    color: var(--slate-800);
}

.text-slate-900 {
    color: var(--slate-900);
}

.bg-sky-600 {
    background-color: var(--sky-600);
}

.bg-white {
    background-color: white;
}

/* Spacing */
.mt-2 {
    margin-top: 0.5rem;
}

.mt-4 {
    margin-top: 1rem;
}

.mt-6 {
    margin-top: 1.5rem;
}

.mt-8 {
    margin-top: 2rem;
}

.mt-10 {
    margin-top: 2.5rem;
}

.mt-12 {
    margin-top: 3rem;
}

.mt-16 {
    margin-top: 4rem;
}

.pt-32 {
    padding-top: 8rem;
}

.pb-20 {
    padding-bottom: 5rem;
}

.py-4 {
    padding-top: 1rem;
    padding-bottom: 1rem;
}

.py-5 {
    padding-top: 1.25rem;
    padding-bottom: 1.25rem;
}

.py-24 {
    padding-top: 6rem;
    padding-bottom: 6rem;
}

.px-5 {
    padding-left: 1.25rem;
    padding-right: 1.25rem;
}

.px-6 {
    padding-left: 1.5rem;
    padding-right: 1.5rem;
}

.px-8 {
    padding-left: 2rem;
    padding-right: 2rem;
}

.px-10 {
    padding-left: 2.5rem;
    padding-right: 2.5rem;
}

.px-16 {
    padding-left: 4rem;
    padding-right: 4rem;
}

.p-6 {
    padding: 1.5rem;
}

.p-8 {
    padding: 2rem;
}

/* Border Radius */
.rounded-full {
    border-radius: 9999px;
}

.rounded-lg {
    border-radius: 0.5rem;
}

.rounded-xl {
    border-radius: 0.75rem;
}

.rounded-2xl {
    border-radius: 1rem;
}

/* Hero Section */
.hero-gradient {
    background: linear-gradient(135deg, var(--sky-50) 0%, var(--sky-100) 100%);
}

.section-hero {
    padding-top: 8rem;
    padding-bottom: 5rem;
}

.hero-content {
    display: grid;
    gap: 3rem;
    align-items: center;
}

.hero-title {
    font-size: 2.25rem;
    line-height: 2.5rem;
    font-weight: 800;
    color: var(--slate-900);
    text-align: center;
}

.hero-description {
    margin-top: 1.5rem;
    font-size: 1.125rem;
    line-height: 1.75rem;
    color: var(--slate-600);
    max-width: 36rem;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

.hero-cta {
    margin-top: 2.5rem;
    text-align: center;
}

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

.book-cover {
    width: 100%;
    max-width: 24rem;
    border-radius: 0.5rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.book-cover:hover {
    transform: scale3d(1.05, 1.05, 1);
}

/* CTA Buttons */
.cta-button {
    display: inline-block;
    background-color: var(--sky-600);
    color: white;
    font-weight: 700;
    text-decoration: none;
    border-radius: 9999px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    will-change: transform, box-shadow;
}

.cta-button:hover {
    transform: translate3d(0, -2px, 0);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
}

.cta-primary {
    font-size: 1.25rem;
    line-height: 1.75rem;
    padding: 1.25rem 2.5rem;
}

.cta-primary-large {
    font-size: 1.25rem;
    line-height: 1.75rem;
    padding: 1.25rem 4rem;
}

.cta-note {
    margin-top: 1rem;
    font-size: 0.875rem;
    line-height: 1.25rem;
    color: var(--slate-500);
}

/* Header */
.header-fixed {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 50;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
}

.header-scrolled {
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
}

.header-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--slate-800);
}

.logo-icon {
    height: 2rem;
    width: 2rem;
    color: var(--sky-600);
}

.logo-text {
    font-weight: 700;
    font-size: 1.25rem;
    line-height: 1.75rem;
}

.nav-desktop {
    display: none;
    align-items: center;
    gap: 2rem;
}

.nav-link {
    color: var(--slate-600);
    text-decoration: none;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--sky-600);
}

.nav-cta {
    background-color: var(--sky-600);
    color: white;
    padding: 0.5rem 1.25rem;
    border-radius: 9999px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
}

.nav-cta:hover {
    transform: translate3d(0, -2px, 0);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
}

/* Mobile Menu */
.hamburger-btn {
    display: block;
    z-index: 50;
    padding: 0.5rem;
    background: none;
    border: none;
    cursor: pointer;
}

.hamburger-lines {
    display: flex;
    flex-direction: column;
    gap: 0.375rem;
}

.hamburger-line {
    width: 1.5rem;
    height: 0.125rem;
    background-color: var(--slate-800);
    transition: all 0.3s ease-in-out;
}

.hamburger-open .line-1 {
    transform: rotate(45deg) translate(5px, 5px);
}

.hamburger-open .line-2 {
    opacity: 0;
}

.hamburger-open .line-3 {
    transform: rotate(-45deg) translate(7px, -6px);
}

.mobile-menu {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background-color: white;
    z-index: 40;
}

.mobile-menu-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    gap: 2rem;
    font-size: 1.5rem;
    line-height: 2rem;
}

.mobile-menu-item {
    color: var(--slate-600);
    text-decoration: none;
    transition: color 0.3s ease;
}

.mobile-menu-item:hover {
    color: var(--sky-600);
}

.mobile-menu-cta {
    background-color: var(--sky-600);
    color: white;
    padding: 1rem 2rem;
    border-radius: 9999px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
}

.mobile-menu-cta:hover {
    transform: translate3d(0, -2px, 0);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
}

/* Sections */
.section-default {
    padding: 6rem 0;
    background-color: white;
}

.section-alt {
    padding: 6rem 0;
    background-color: var(--slate-50);
}

.section-title {
    font-size: 2.25rem;
    line-height: 2.5rem;
    font-weight: 700;
    color: var(--slate-900);
    margin-bottom: 0;
}

.section-description {
    margin-top: 1rem;
    font-size: 1.125rem;
    line-height: 1.75rem;
    color: var(--slate-600);
}

.content-center {
    text-align: center;
    max-width: 48rem;
    margin: 0 auto;
}

/* Stats Section */
.stats-grid {
    margin-top: 4rem;
    display: grid;
    gap: 2rem;
    text-align: center;
    grid-template-columns: 1fr;
}

.stat-card {
    background-color: var(--slate-50);
    padding: 2rem;
    border-radius: 0.75rem;
}

.stat-number {
    font-size: 3rem;
    line-height: 1;
    font-weight: 700;
    color: var(--sky-600);
    margin: 0;
}

.stat-description {
    margin-top: 0.5rem;
    color: var(--slate-600);
}

/* Solution Section */
.solution-content {
    margin-top: 6rem;
    max-width: 64rem;
    margin-left: auto;
    margin-right: auto;
}

.solution-title {
    font-size: 1.875rem;
    line-height: 2.25rem;
    font-weight: 700;
    text-align: center;
    margin: 0;
}

.solution-intro {
    margin-top: 1rem;
    text-align: center;
    color: var(--slate-600);
}

.solution-box {
    margin-top: 2rem;
    background-color: var(--slate-50);
    border: 1px solid var(--slate-200);
    border-radius: 0.75rem;
    padding: 2rem;
}

.solution-box-title {
    font-weight: 700;
    font-size: 1.25rem;
    line-height: 1.75rem;
    margin: 0 0 1rem 0;
}

.solution-list {
    margin: 0;
    padding: 0;
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.solution-item {
    display: flex;
    align-items: flex-start;
}

.check-icon {
    height: 1.5rem;
    width: 1.5rem;
    color: var(--sky-500);
    margin-right: 0.75rem;
    flex-shrink: 0;
    margin-top: 0.125rem;
}

/* Author Section */
.author-grid {
    display: grid;
    gap: 3rem;
    align-items: center;
}

.author-image-container {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.author-image {
    border-radius: 50%;
    width: 16rem;
    height: 16rem;
    object-fit: cover;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
}

.author-title {
    margin-top: 1rem;
    text-align: center;
    font-size: 1.125rem;
    line-height: 1.75rem;
    font-weight: 600;
    color: var(--slate-800);
}

.author-intro {
    margin-top: 1rem;
    font-size: 1.125rem;
    line-height: 1.75rem;
    color: var(--slate-600);
}

.author-credentials {
    margin-top: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.credential-title {
    font-weight: 700;
    font-size: 1.25rem;
    line-height: 1.75rem;
    margin: 0;
}

.credential-list {
    margin-top: 0.5rem;
    list-style-type: disc;
    list-style-position: inside;
    color: var(--slate-600);
    padding-left: 0;
}

/* Video Section */
.video-container {
    margin-top: 3rem;
}

.video-wrapper {
    margin: 0 auto;
    max-width: 64rem;
}

.video-frame {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 56.25%;
    border-radius: 0.75rem;
    overflow: hidden;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    background-color: var(--slate-900);
}

.video-iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.video-description {
    margin-top: 2rem;
    background-color: var(--slate-50);
    border-radius: 0.75rem;
    padding: 1.5rem;
    text-align: left;
}

.video-description-title {
    font-weight: 700;
    font-size: 1.25rem;
    line-height: 1.75rem;
    color: var(--slate-800);
    margin: 0 0 0.75rem 0;
}

.video-benefits {
    display: grid;
    gap: 1rem;
}

.benefits-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin: 0;
    padding: 0;
    list-style: none;
}

.benefit-item {
    display: flex;
    align-items: flex-start;
}

.benefit-check {
    height: 1.25rem;
    width: 1.25rem;
    color: var(--sky-500);
    margin-right: 0.5rem;
    margin-top: 0.25rem;
    flex-shrink: 0;
}

/* Delay Math Section */
.delay-math {
    margin-top: 4rem;
    max-width: 64rem;
    margin-left: auto;
    margin-right: auto;
}

.delay-title {
    font-size: 1.5rem;
    line-height: 2rem;
    font-weight: 700;
    text-align: center;
    margin: 0;
}

.delay-comparison {
    margin-top: 2rem;
    display: grid;
    gap: 2rem;
}

.delay-card {
    padding: 2rem;
    border-radius: 0.75rem;
    border: 2px solid;
}

.delay-bad {
    background-color: var(--red-50);
    border-color: var(--red-200);
}

.delay-good {
    background-color: var(--green-50);
    border-color: var(--green-200);
}

.delay-age {
    font-size: 1.125rem;
    line-height: 1.75rem;
    font-weight: 600;
}

.age-bad {
    color: var(--red-600);
}

.age-good {
    color: var(--green-600);
}

.delay-amount {
    font-size: 3rem;
    line-height: 1;
    font-weight: 800;
    margin: 0.5rem 0;
}

.amount-bad {
    color: var(--red-800);
}

.amount-good {
    color: var(--green-800);
}

.delay-note {
    color: var(--slate-600);
    margin: 0;
}

.delay-conclusion {
    text-align: center;
    margin-top: 2rem;
    font-weight: 600;
    font-size: 1.25rem;
    line-height: 1.75rem;
    color: var(--slate-700);
}

/* Timeline Section */
.timeline-grid {
    margin-top: 4rem;
    display: grid;
    gap: 2rem;
}

.timeline-card {
    border: 1px solid var(--slate-200);
    background-color: white;
    padding: 2rem;
    border-radius: 0.75rem;
}

.timeline-featured {
    border: 2px solid var(--sky-500);
    ring: 2px solid var(--sky-500);
}

.timeline-title {
    font-size: 1.5rem;
    line-height: 2rem;
    font-weight: 700;
    margin: 0;
}

.timeline-list {
    margin-top: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    list-style: none;
    padding: 0;
}

.timeline-item {
    display: flex;
    align-items: flex-start;
}

.timeline-check {
    height: 1.25rem;
    width: 1.25rem;
    color: var(--sky-500);
    margin-right: 0.5rem;
    margin-top: 0.25rem;
    flex-shrink: 0;
}

/* Different Section */
.different-container {
    max-width: 64rem;
}

.different-grid {
    margin-top: 4rem;
    display: grid;
    gap: 2rem;
}

.different-card {
    background-color: var(--slate-50);
    padding: 2rem;
    border-radius: 0.75rem;
}

.different-title {
    font-weight: 700;
    font-size: 1.25rem;
    line-height: 1.75rem;
    margin: 0;
}

.different-description {
    color: var(--slate-600);
    margin-top: 0.5rem;
}

/* CTA Section */
.section-cta {
    padding: 6rem 0;
}

.cta-container {
    text-align: center;
}

.cta-content {
    max-width: 48rem;
    margin: 0 auto;
}

.cta-title {
    font-size: 2.25rem;
    line-height: 2.5rem;
    font-weight: 800;
    color: var(--slate-900);
    margin: 0;
}

.cta-description {
    margin-top: 1.5rem;
    font-size: 1.125rem;
    line-height: 1.75rem;
    color: var(--slate-600);
}

.cta-box {
    margin-top: 2.5rem;
    background-color: white;
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    display: inline-block;
}

.cta-box-label {
    color: var(--slate-500);
    margin: 0;
}

.cta-box-price {
    font-size: 3.75rem;
    line-height: 1;
    font-weight: 900;
    color: var(--slate-800);
    margin: 0.5rem 0;
}

.cta-features {
    margin-top: 1.5rem;
    text-align: left;
    max-width: 18rem;
    margin-left: auto;
    margin-right: auto;
    color: var(--slate-600);
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.cta-feature {
    display: flex;
    align-items: center;
    margin: 0;
}

.feature-check {
    height: 1.25rem;
    width: 1.25rem;
    color: var(--green-500);
    margin-right: 0.5rem;
}

.cta-urgency {
    margin-top: 3rem;
    color: var(--slate-700);
}

.urgency-title {
    font-size: 1.5rem;
    line-height: 2rem;
    font-weight: 700;
    margin: 0;
}

.urgency-description {
    margin-top: 0.5rem;
}

/* FAQ Section */
.faq-container {
    max-width: 64rem;
}

.faq-intro {
    color: var(--slate-600);
    text-align: center;
    margin-top: 0.75rem;
}

.faq-list {
    margin-top: 2.5rem;
    border-top: 1px solid var(--slate-200);
    border-bottom: 1px solid var(--slate-200);
    divide-y: 1px solid var(--slate-200);
}

.faq-item {
    padding: 1.25rem 0;
}

.faq-button {
    width: 100%;
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    text-align: left;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
    font: inherit;
}

.faq-question {
    font-size: 1.125rem;
    line-height: 1.75rem;
    font-weight: 600;
    color: var(--slate-800);
    padding-right: 1.5rem;
}

.faq-icon {
    font-size: 1.5rem;
    line-height: 1;
    color: var(--slate-500);
    user-select: none;
    transition: transform 0.2s ease;
}

.faq-item[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    display: none;
    padding-top: 0.75rem;
    color: var(--slate-600);
    animation: fadeIn 0.3s ease-in;
}

.faq-item[aria-expanded="true"] .faq-answer {
    display: block;
}

.faq-answer-intro {
    margin-bottom: 0.5rem;
}

.faq-list-items {
    list-style-type: disc;
    list-style-position: inside;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin: 0;
    padding-left: 0;
}

/* Footer */
.footer-section {
    background-color: var(--slate-800);
    color: var(--slate-400);
}

.footer-content {
    padding: 3rem 1.5rem;
    text-align: center;
}

.footer-logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--slate-200);
}

.footer-logo-icon {
    height: 2rem;
    width: 2rem;
    color: var(--sky-500);
}

.footer-logo-text {
    font-weight: 700;
    font-size: 1.25rem;
    line-height: 1.75rem;
}

.footer-description {
    margin-top: 1rem;
    max-width: 28rem;
    margin-left: auto;
    margin-right: auto;
}

.footer-copyright {
    margin-top: 2rem;
    font-size: 0.875rem;
    line-height: 1.25rem;
}

/* Popup */
.popup {
    position: fixed;
    bottom: 1.25rem;
    right: 1.25rem;
    z-index: 50;
    transform: translate3d(0, 120%, 0);
    transition: transform 0.5s ease-in-out;
}

.popup.show {
    transform: translate3d(0, 0, 0);
}

.popup-content {
    background-color: white;
    border-radius: 0.5rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    padding: 1.5rem;
    max-width: 24rem;
    width: 100%;
    position: relative;
    border: 1px solid var(--slate-200);
}

.popup-close {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    color: var(--slate-400);
    background: none;
    border: none;
    font-size: 1.5rem;
    line-height: 1;
    cursor: pointer;
    transition: color 0.3s ease;
}

.popup-close:hover {
    color: var(--slate-600);
}

.popup-inner {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.popup-image {
    width: 5rem;
    border-radius: 0.375rem;
}

.popup-title {
    font-weight: 700;
    color: var(--slate-800);
    margin: 0;
}

.popup-description {
    font-size: 0.875rem;
    line-height: 1.25rem;
    color: var(--slate-600);
    margin: 0.25rem 0;
}

.popup-cta {
    font-size: 0.875rem;
    line-height: 1.25rem;
    font-weight: 600;
    color: var(--sky-600);
    text-decoration: none;
    margin-top: 0.5rem;
    display: inline-block;
    transition: text-decoration 0.3s ease;
}

.popup-cta:hover {
    text-decoration: underline;
}

/* Scroll Reveal Animation */
.scroll-reveal {
    opacity: 0;
    transform: translate3d(0, 30px, 0);
    transition: opacity 0.8s cubic-bezier(0.5, 0, 0, 1), transform 0.8s cubic-bezier(0.5, 0, 0, 1);
}

.scroll-reveal.visible {
    opacity: 1;
    transform: translate3d(0, 0, 0);
}

.scroll-reveal[data-delay="100"] {
    transition-delay: 100ms;
}

.scroll-reveal[data-delay="200"] {
    transition-delay: 200ms;
}

.scroll-reveal[data-delay="300"] {
    transition-delay: 300ms;
}

.scroll-reveal[data-delay="400"] {
    transition-delay: 400ms;
}

.scroll-reveal[data-delay="500"] {
    transition-delay: 500ms;
}

/* Keyframe Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

/* Responsive Design */
@media (min-width: 768px) {
    .nav-desktop {
        display: flex;
    }
    
    .hamburger-btn {
        display: none;
    }
    
    .hero-content {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    
    .hero-title {
        font-size: 3.75rem;
        line-height: 1;
        text-align: left;
    }
    
    .hero-description {
        text-align: left;
        margin-left: 0;
        margin-right: 0;
    }
    
    .hero-cta {
        text-align: left;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    
    .author-grid {
        grid-template-columns: 2fr 3fr;
    }
    
    .author-image {
        width: 20rem;
        height: 20rem;
    }
    
    .video-benefits {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    
    .delay-comparison {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    
    .timeline-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }
    
    .different-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    
    .cta-title {
        font-size: 3rem;
        line-height: 1;
    }
}

@media (min-width: 1024px) {
    .stats-grid {
        grid-template-columns: repeat(4, minmax(0, 1fr));
    }
}

/* Performance optimizations */
* {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    .scroll-reveal,
    .cta-button,
    .hamburger-line,
    .faq-icon,
    .popup {
        transition: none;
    }
    
    .book-cover:hover {
        transform: none;
    }
}

/* Focus styles for accessibility */
button:focus,
a:focus {
    outline: 2px solid var(--sky-500);
    outline-offset: 2px;
}

/* Print styles */
@media print {
    .header-fixed,
    .popup {
        display: none !important;
    }
    
    body {
        font-size: 12pt;
        line-height: 1.5;
    }
}