/* ===== Design Tokens ===== */
:root {
    --orange: #F4890B;
    --orange-dark: #C9700A;
    --orange-light: #FEF3E2;
    --white: #FFFFFF;
    --gray-50: #F9FAFB;
    --gray-700: #374151;
    --gray-900: #111827;
    --sunshine: #FFD60A;
    --max-width: 1100px;
    --radius: 12px;
}

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

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 18px;
    line-height: 1.6;
    color: var(--gray-700);
    background: var(--white);
}

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

a { color: var(--orange); text-decoration: none; }
a:hover { color: var(--orange-dark); }

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Nav ===== */
.nav {
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid #e5e7eb;
    z-index: 100;
    padding: 12px 0;
}

.nav .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--gray-900);
}

.nav-icon {
    width: 40px;
    height: 40px;
    border-radius: 22%;
}

.nav-title {
    font-size: 20px;
    font-weight: 700;
}

/* ===== Buttons ===== */
.btn-primary {
    background: var(--orange);
    color: white;
    border-radius: var(--radius);
    padding: 14px 28px;
    font-size: 18px;
    font-weight: 600;
    text-decoration: none;
    display: inline-block;
    transition: background 0.2s;
}

.btn-primary:hover {
    background: var(--orange-dark);
    color: white;
}

.btn-small {
    padding: 10px 20px;
    font-size: 16px;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 10px;
}

.btn-tip-nav {
    display: inline-block;
    background: transparent;
    color: var(--gray-700);
    border: 1.5px solid #d1d5db;
    border-radius: var(--radius);
    padding: 10px 18px;
    font-size: 15px;
    font-weight: 500;
    text-decoration: none;
    transition: border-color 0.2s, color 0.2s;
}

.btn-tip-nav:hover {
    border-color: var(--orange);
    color: var(--orange);
}

/* ===== Hero ===== */
.hero {
    padding: 80px 0 60px;
    background: linear-gradient(180deg, var(--orange-light) 0%, var(--white) 100%);
}

.hero .container {
    display: flex;
    align-items: center;
    gap: 60px;
}

.hero-text {
    flex: 1;
}

.hero-text h1 {
    font-size: 48px;
    font-weight: 700;
    color: var(--gray-900);
    line-height: 1.15;
    margin-bottom: 20px;
}

.hero-text p {
    font-size: 20px;
    margin-bottom: 32px;
    color: var(--gray-700);
}

.hero-actions {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}

.hero-screenshot {
    flex: 0 0 280px;
}

.hero-screenshot img {
    border-radius: 24px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
}

/* ===== Features ===== */
.features {
    padding: 80px 0;
}

.section-title {
    font-size: 32px;
    font-weight: 700;
    color: var(--gray-900);
    text-align: center;
    margin-bottom: 48px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
}

/* Center the 5th card when it's alone on the last row */
.feature-card:last-child:nth-child(odd) {
    grid-column: 1 / -1;
    max-width: calc(50% - 16px);
    margin: 0 auto;
}

.feature-card {
    background: var(--gray-50);
    border-radius: var(--radius);
    padding: 32px;
}

.feature-icon {
    font-size: 36px;
    margin-bottom: 12px;
}

.feature-card h3 {
    font-size: 20px;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 8px;
}

.feature-card p {
    font-size: 16px;
    color: var(--gray-700);
}

/* ===== Screenshots ===== */
.screenshots {
    padding: 80px 0;
    background: var(--gray-50);
}

.screenshots-row {
    display: flex;
    justify-content: center;
    gap: 32px;
    flex-wrap: wrap;
}

.screenshot-frame {
    flex: 0 0 220px;
    border-radius: 24px;
    overflow: hidden;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12);
    transform: rotate(-2deg);
    transition: transform 0.3s;
}

.screenshot-frame:nth-child(2) {
    transform: rotate(0deg);
}

.screenshot-frame:nth-child(3) {
    transform: rotate(2deg);
}

.screenshot-frame:hover {
    transform: rotate(0deg) scale(1.03);
}

.screenshot-frame img {
    width: 100%;
    display: block;
}

/* ===== Preview Video ===== */
.preview {
    padding: 80px 0;
}

.preview-wrapper {
    max-width: 500px;
    margin: 0 auto;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12);
}

.preview-wrapper video {
    width: 100%;
    display: block;
}

/* ===== Grade Levels ===== */
.grades {
    padding: 80px 0;
}

.grades-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.grade-card {
    text-align: center;
    padding: 40px 24px;
    background: var(--orange-light);
    border-radius: var(--radius);
}

.grade-card h3 {
    font-size: 28px;
    font-weight: 700;
    color: var(--orange);
    margin-bottom: 8px;
}

.grade-card .book-count {
    font-size: 40px;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 4px;
}

.grade-card .book-label {
    font-size: 16px;
    color: var(--gray-700);
}

/* ===== Footer ===== */
.footer {
    padding: 40px 0;
    border-top: 1px solid #e5e7eb;
    text-align: center;
    font-size: 14px;
    color: var(--gray-700);
}

.footer p {
    margin-bottom: 8px;
}

.footer a {
    color: var(--orange);
}

.btn-tip {
    display: inline-block;
    background: var(--orange-light);
    color: var(--orange-dark);
    border: 1.5px solid var(--orange);
    border-radius: 20px;
    padding: 8px 20px;
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
    transition: background 0.2s;
}

.btn-tip:hover {
    background: var(--orange);
    color: white;
}

.disclaimer {
    font-style: italic;
    margin-bottom: 12px;
}

/* ===== Privacy Page ===== */
.privacy-content {
    max-width: 700px;
    margin: 0 auto;
    padding: 60px 24px;
}

.privacy-content h1 {
    font-size: 36px;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 4px;
}

.privacy-content .subtitle {
    font-size: 20px;
    color: var(--gray-700);
    margin-bottom: 8px;
}

.privacy-content .last-updated {
    font-size: 14px;
    color: var(--gray-700);
    margin-bottom: 40px;
}

.privacy-content h2 {
    font-size: 24px;
    font-weight: 700;
    color: var(--gray-900);
    margin-top: 32px;
    margin-bottom: 12px;
}

.privacy-content p {
    margin-bottom: 16px;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .hero .container {
        flex-direction: column;
        text-align: center;
    }

    .hero-text h1 {
        font-size: 36px;
    }

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

    .hero-screenshot {
        flex: 0 0 auto;
        max-width: 240px;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .screenshots-row {
        gap: 20px;
    }

    .screenshot-frame {
        flex: 0 0 160px;
    }

    .screenshot-frame,
    .screenshot-frame:nth-child(2),
    .screenshot-frame:nth-child(3) {
        transform: rotate(0deg);
    }

    .grades-grid {
        grid-template-columns: 1fr;
    }

    .nav-title {
        font-size: 16px;
    }

    .btn-primary {
        padding: 12px 20px;
        font-size: 16px;
    }
}

@media (max-width: 480px) {
    .hero-text h1 {
        font-size: 28px;
    }

    .section-title {
        font-size: 26px;
    }

    .screenshot-frame {
        flex: 0 0 140px;
    }
}