/* ==========================================================================
   Base Styles
   ========================================================================== */

:root {
    --primary-color: #000000;
    --secondary-color: #333333;
    --accent-color: #000000;
    --text-primary: #000000;
    --text-secondary: #666666;
    --background: #FFFFFF;
    --background-light: #F5F5F5;
    --border-color: #E0E0E0;
    --success-color: #000000;
}

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

body {
    font-family: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    color: var(--text-primary);
    line-height: 1.6;
    background-color: var(--background);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ==========================================================================
   Header
   ========================================================================== */

.header {
    background: var(--primary-color);
    color: white;
    padding: 40px 0;
    text-align: center;
    border-bottom: 4px solid var(--primary-color);
}

.app-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.app-subtitle {
    font-size: 1.2rem;
    font-weight: 400;
    opacity: 0.95;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */

.hero {
    padding: 80px 0;
    background-color: var(--background);
}

.hero-content {
    display: block;
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 20px;
    line-height: 1.3;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 30px;
    line-height: 1.8;
}

.download-button {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background-color: var(--text-primary);
    color: white;
    padding: 16px 32px;
    border-radius: 12px;
    text-decoration: none;
    font-size: 1.1rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.download-button:hover {
    background-color: #222;
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

.apple-icon {
    width: 24px;
    height: 24px;
}

.free-badge {
    display: inline-block;
    margin-top: 15px;
    font-size: 0.9rem;
    color: var(--success-color);
    font-weight: 600;
}

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

.screenshot-main {
    max-width: 100%;
    height: auto;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
}

.screenshots-gallery {
    margin-top: 50px;
    width: 100%;
    overflow: hidden;
}

.screenshots-slider {
    display: flex;
    gap: 20px;
    padding: 10px 0;
    overflow-x: auto;
    scroll-snap-type: x mandatory;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
    scrollbar-color: var(--text-secondary) var(--background-light);
}

.screenshots-slider::-webkit-scrollbar {
    height: 8px;
}

.screenshots-slider::-webkit-scrollbar-track {
    background: var(--background-light);
    border-radius: 4px;
}

.screenshots-slider::-webkit-scrollbar-thumb {
    background: var(--text-secondary);
    border-radius: 4px;
}

.screenshots-slider::-webkit-scrollbar-thumb:hover {
    background: var(--text-primary);
}

.screenshot-item {
    flex-shrink: 0;
    width: 250px;
    height: auto;
    border-radius: 16px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
    scroll-snap-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.screenshot-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.2);
}

/* ==========================================================================
   Features Section
   ========================================================================== */

.section-title {
    text-align: center;
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 60px;
}

.section-icon {
    display: inline-block;
    margin-right: 10px;
    font-size: 2rem;
}

.features {
    padding: 80px 0;
    background-color: var(--background);
}

.feature-item {
    max-width: 800px;
    margin: 0 auto 60px;
    padding: 0 20px;
}

.feature-item:last-child {
    margin-bottom: 0;
}

.feature-heading {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 20px;
    line-height: 1.5;
}

.feature-text {
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.9;
}

/* ==========================================================================
   Target Audience Section
   ========================================================================== */

.target-audience {
    padding: 80px 0;
    background-color: var(--background);
}

.audience-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
    margin-top: 20px;
}

.audience-item {
    background: var(--primary-color);
    color: white;
    padding: 40px;
    border-radius: 16px;
    text-align: center;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

.audience-age {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 15px;
}

.audience-description {
    font-size: 1rem;
    line-height: 1.7;
    opacity: 0.95;
}

/* ==========================================================================
   Learning Effects Section
   ========================================================================== */

.learning-effects {
    padding: 80px 0;
    background-color: var(--background-light);
}

.effects-list {
    list-style: none;
    max-width: 900px;
    margin: 0 auto;
}

.effect-item {
    display: flex;
    align-items: flex-start;
    gap: 15px;
    padding: 25px;
    margin-bottom: 20px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.effect-icon {
    flex-shrink: 0;
    width: 24px;
    height: 24px;
    background-color: var(--success-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.9rem;
}

.effect-text {
    font-size: 1.05rem;
    color: var(--text-primary);
    line-height: 1.7;
}

/* ==========================================================================
   Screenshots Section
   ========================================================================== */

.screenshots {
    padding: 80px 0;
    background-color: var(--background);
}

.screenshots-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
    margin-top: 20px;
}

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

.screenshot-img {
    width: 100%;
    height: auto;
    border-radius: 16px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.12);
    margin-bottom: 15px;
}

.screenshot-caption {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
}

/* ==========================================================================
   Developer Section
   ========================================================================== */

.developer {
    padding: 80px 0;
    background-color: var(--background-light);
}

.developer-content {
    max-width: 800px;
    margin: 0 auto;
}

.developer-profile {
    padding: 0 20px;
}

.developer-text {
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.9;
    margin-bottom: 25px;
}

.developer-background {
    margin-top: 40px;
    padding: 30px;
    background: white;
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
}

.developer-label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 15px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.developer-history {
    list-style: none;
    padding: 0;
}

.developer-history li {
    font-size: 1rem;
    color: var(--text-secondary);
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color);
}

.developer-history li:last-child {
    border-bottom: none;
}

/* ==========================================================================
   CTA Section
   ========================================================================== */

.cta {
    padding: 100px 0;
    background: var(--primary-color);
    color: white;
    text-align: center;
}

.cta-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 40px;
    line-height: 1.4;
}

.download-button-large {
    font-size: 1.2rem;
    padding: 20px 40px;
    background-color: white;
    color: var(--primary-color);
}

.download-button-large:hover {
    background-color: #f8f9fa;
    color: var(--primary-color);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
    background-color: var(--text-primary);
    color: white;
    padding: 40px 0;
    text-align: center;
}

.footer-content {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.footer-text {
    font-size: 0.95rem;
    opacity: 0.9;
}

.footer-text a {
    color: white;
    text-decoration: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.3);
    transition: border-color 0.3s ease;
}

.footer-text a:hover {
    border-bottom-color: white;
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */

@media (max-width: 768px) {
    .app-title {
        font-size: 2rem;
    }

    .app-subtitle {
        font-size: 1rem;
    }

    .hero {
        padding: 60px 0;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-description {
        font-size: 1rem;
    }

    .screenshot-item {
        width: 200px;
    }

    .section-title {
        font-size: 1.8rem;
        margin-bottom: 40px;
    }

    .feature-heading {
        font-size: 1.5rem;
    }

    .feature-text {
        font-size: 1rem;
    }

    .audience-content {
        grid-template-columns: 1fr;
    }

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

    .cta-title {
        font-size: 1.8rem;
    }

    .download-button-large {
        font-size: 1.1rem;
        padding: 16px 32px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.6rem;
    }

    .section-title {
        font-size: 1.5rem;
    }

    .feature-heading {
        font-size: 1.3rem;
    }

    .feature-text {
        font-size: 0.95rem;
    }

    .audience-item {
        padding: 30px 20px;
    }

    .developer-text {
        font-size: 0.95rem;
    }

    .developer-background {
        padding: 20px;
    }

    .cta {
        padding: 60px 0;
    }

    .cta-title {
        font-size: 1.5rem;
    }
}