/**
 * Responsive Styles
 */

/* ============================================
   タブレット (768px以下)
   ============================================ */

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    h3 {
        font-size: 1.25rem;
    }

    .container {
        padding: 0 1rem;
    }

    .hero-text h1 {
        font-size: 2rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .btn-lg {
        width: 100%;
    }

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

    .hero-image {
        display: none;
    }

    .chapter-list {
        grid-template-columns: 1fr;
    }

    .chapter-item {
        grid-template-columns: auto 1fr;
    }

    .key-points-grid {
        grid-template-columns: 1fr;
    }

    .cta-content h2 {
        font-size: 1.875rem;
    }

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

    .cta-section .btn {
        width: 100%;
    }

    .author-message-content blockquote {
        font-size: 1.125rem;
    }
}

/* ============================================
   スマートフォン (640px以下)
   ============================================ */

@media (max-width: 640px) {
    html {
        font-size: 14px;
    }

    h1 {
        font-size: 1.75rem;
    }

    h2 {
        font-size: 1.25rem;
    }

    h3 {
        font-size: 1.125rem;
    }

    p {
        font-size: 0.95rem;
    }

    .container {
        padding: 0 1rem;
    }

    header {
        padding: 0.75rem 0;
    }

    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    .site-title {
        font-size: 1.25rem;
    }

    .site-navigation {
        width: 100%;
    }

    /* Hero Section */
    .hero-section {
        min-height: auto;
        padding: 2rem 0;
    }

    .hero-section::before {
        opacity: 0.15;
    }

    .hero-text h1 {
        font-size: 1.75rem;
        margin-bottom: 1rem;
    }

    .hero-text p {
        font-size: 1rem;
    }

    .hero-buttons {
        gap: 0.75rem;
    }

    .btn {
        padding: 0.625rem 1.5rem;
        font-size: 0.95rem;
    }

    .btn-lg {
        padding: 1rem 1.5rem;
        font-size: 1rem;
    }

    .hero-features {
        flex-direction: column;
        gap: 0.75rem;
    }

    /* Author Message */
    .author-message-section {
        padding: 3rem 0;
    }

    .author-message-content blockquote {
        font-size: 1rem;
        padding-left: 1rem;
        border-left-width: 3px;
    }

    /* Book Content */
    .book-content-section {
        padding: 3rem 0;
    }

    .chapter-item {
        padding: 1rem;
        gap: 0.75rem;
    }

    .chapter-number {
        width: 3rem;
        height: 3rem;
        font-size: 0.875rem;
    }

    .chapter-info h3 {
        font-size: 1rem;
    }

    .chapter-info p {
        font-size: 0.875rem;
    }

    /* Key Points */
    .key-points-section {
        padding: 3rem 0;
    }

    .key-point-card {
        padding: 1.5rem;
    }

    .key-point-icon {
        width: 2.5rem;
        height: 2.5rem;
        font-size: 1.25rem;
    }

    .key-point-card h3 {
        font-size: 1rem;
    }

    .key-point-card p {
        font-size: 0.875rem;
    }

    /* FAQ */
    .faq-section {
        padding: 3rem 0;
    }

    .faq-container {
        max-width: 100%;
    }

    .faq-question {
        padding: 1rem;
        font-size: 0.95rem;
    }

    .faq-answer {
        padding: 0;
    }

    .faq-item.active .faq-answer {
        padding: 1rem;
    }

    .faq-answer p {
        font-size: 0.875rem;
    }

    /* CTA */
    .cta-section {
        padding: 4rem 0;
    }

    .cta-content h2 {
        font-size: 1.5rem;
        margin-bottom: 1rem;
    }

    .cta-content p {
        font-size: 1rem;
        margin-bottom: 1.5rem;
    }

    .cta-note {
        font-size: 0.75rem;
    }

    /* Footer */
    footer {
        padding: 2rem 0;
    }

    .footer-title {
        font-size: 1rem;
    }
}

/* ============================================
   超小型デバイス (480px以下)
   ============================================ */

@media (max-width: 480px) {
    html {
        font-size: 13px;
    }

    h1 {
        font-size: 1.5rem;
    }

    h2 {
        font-size: 1.125rem;
    }

    .hero-text h1 {
        font-size: 1.5rem;
    }

    .cta-content h2 {
        font-size: 1.25rem;
    }

    .btn {
        padding: 0.5rem 1rem;
        font-size: 0.875rem;
    }

    .btn-lg {
        padding: 0.75rem 1rem;
    }

    .chapter-number {
        width: 2.5rem;
        height: 2.5rem;
        font-size: 0.75rem;
    }

    .key-point-icon {
        width: 2rem;
        height: 2rem;
        font-size: 1rem;
    }
}

/* ============================================
   ダークモード対応
   ============================================ */

@media (prefers-color-scheme: dark) {
    :root {
        --background-color: #1a1a1a;
        --background-light: #2d2d2d;
        --background-dark: #0f0f0f;
        --text-color: #e5e5e5;
        --text-light: #b0b0b0;
        --text-lighter: #808080;
        --border-color: #404040;
        --border-light: #2d2d2d;
    }

    body {
        background-color: var(--background-color);
        color: var(--text-color);
    }

    .hero-section {
        background: linear-gradient(135deg, var(--background-light) 0%, var(--background-dark) 100%);
    }

    .author-message-section {
        background-color: rgba(255, 255, 255, 0.05);
    }

    .key-points-section {
        background-color: rgba(255, 255, 255, 0.05);
    }

    .chapter-item,
    .key-point-card,
    .faq-item {
        background-color: var(--background-light);
        border-color: var(--border-color);
    }

    .faq-answer {
        background-color: var(--background-dark);
    }

    footer {
        background-color: var(--background-light);
        border-top-color: var(--border-color);
    }
}

/* ============================================
   高解像度ディスプレイ対応
   ============================================ */

@media (min-width: 1920px) {
    .container {
        max-width: 1600px;
    }

    h1 {
        font-size: 4rem;
    }

    h2 {
        font-size: 2.5rem;
    }

    .hero-text h1 {
        font-size: 4rem;
    }

    .cta-content h2 {
        font-size: 3.5rem;
    }
}

/* ============================================
   印刷用スタイル
   ============================================ */

@media print {
    header,
    footer,
    .hero-buttons,
    .cta-buttons {
        display: none;
    }

    body {
        background-color: white;
        color: black;
    }

    a {
        color: black;
    }

    .container {
        max-width: 100%;
    }
}