/* リセットとベーススタイル */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Noto Sans JP', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

/* スライドショーコンテナ */
.slideshow-container {
    max-width: 1000px;
    width: 100%;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    position: relative;
}

/* ヘッダー */
header {
    background: linear-gradient(135deg, #2c3e50, #3498db);
    color: white;
    padding: 30px;
    text-align: center;
    position: relative;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 10px;
}

header h1 i {
    margin-right: 15px;
    color: #f39c12;
}

.slide-counter {
    position: absolute;
    top: 30px;
    right: 30px;
    font-size: 1.2rem;
    background: rgba(255, 255, 255, 0.2);
    padding: 8px 16px;
    border-radius: 20px;
}

/* スライドコンテンツ */
.slide {
    display: none;
    padding: 40px;
    min-height: 600px;
    animation: fadeIn 0.5s ease-in-out;
}

.slide.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.slide-content h2 {
    font-size: 2.2rem;
    color: #2c3e50;
    margin-bottom: 30px;
    text-align: center;
    border-bottom: 3px solid #3498db;
    padding-bottom: 15px;
}

.slide-content h2 i {
    margin-right: 10px;
    color: #3498db;
}

/* スライド1: イントロダクション */
.intro-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.intro-card {
    background: linear-gradient(135deg, #f8f9fa, #e9ecef);
    padding: 25px;
    border-radius: 15px;
    text-align: center;
    transition: transform 0.3s ease;
    border-left: 5px solid #3498db;
}

.intro-card:hover {
    transform: translateY(-5px);
}

.intro-card i {
    font-size: 2.5rem;
    color: #3498db;
    margin-bottom: 15px;
}

.intro-card h3 {
    font-size: 1.3rem;
    color: #2c3e50;
    margin-bottom: 10px;
}

.intro-card p {
    color: #7f8c8d;
    line-height: 1.6;
}

.highlight-box {
    background: #f8f9fa;
    border: 2px solid #3498db;
    border-radius: 15px;
    padding: 25px;
    margin-top: 20px;
}

.highlight-box h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 1.4rem;
}

.highlight-box h3 i {
    color: #f39c12;
    margin-right: 10px;
}

.highlight-box ul {
    list-style: none;
    padding-left: 0;
}

.highlight-box li {
    padding: 8px 0;
    padding-left: 25px;
    position: relative;
    color: #34495e;
    line-height: 1.6;
}

.highlight-box li::before {
    content: "✓";
    color: #27ae60;
    font-weight: bold;
    position: absolute;
    left: 0;
}

/* スライド2: 基本的な文字と発音 */
.alphabet-section h3 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 1.5rem;
    text-align: center;
}

.vowel-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 15px;
    margin-bottom: 30px;
}

.vowel-card {
    background: linear-gradient(135deg, #fff, #f8f9fa);
    border: 2px solid #e9ecef;
    border-radius: 12px;
    padding: 20px;
    text-align: center;
    transition: all 0.3s ease;
}

.vowel-card:hover {
    border-color: #3498db;
    transform: scale(1.05);
}

.czech-letter {
    display: block;
    font-size: 2.5rem;
    font-weight: 600;
    color: #e74c3c;
    margin-bottom: 8px;
    font-family: 'Noto Serif', serif;
}

.pronunciation {
    display: block;
    font-size: 1.2rem;
    color: #3498db;
    margin-bottom: 5px;
    font-style: italic;
}

.example {
    font-size: 0.9rem;
    color: #7f8c8d;
}

.note-box {
    background: #fff3cd;
    border: 1px solid #ffeaa7;
    border-radius: 10px;
    padding: 20px;
    margin-top: 20px;
    display: flex;
    align-items: flex-start;
}

.note-box i {
    color: #f39c12;
    margin-right: 15px;
    margin-top: 3px;
    font-size: 1.2rem;
}

.note-box p {
    color: #856404;
    line-height: 1.6;
}

/* スライド3: 特殊文字と発音 */
.special-chars h3 {
    color: #2c3e50;
    margin-bottom: 25px;
    margin-top: 30px;
    font-size: 1.4rem;
    text-align: center;
    border-bottom: 2px solid #ecf0f1;
    padding-bottom: 10px;
}

.special-chars h3:first-child {
    margin-top: 0;
}

.char-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 15px;
    margin-bottom: 25px;
}

.char-item {
    background: white;
    border: 2px solid #ecf0f1;
    border-radius: 10px;
    padding: 15px;
    text-align: center;
    transition: all 0.3s ease;
}

.char-item:hover {
    border-color: #3498db;
    box-shadow: 0 5px 15px rgba(52, 152, 219, 0.2);
}

.czech-letter.large {
    font-size: 2.2rem;
    color: #e74c3c;
    font-weight: 700;
    display: block;
    margin-bottom: 8px;
    font-family: 'Noto Serif', serif;
}

.description {
    font-size: 0.85rem;
    color: #7f8c8d;
    display: block;
    margin-top: 5px;
}

/* スライド4: 発音のルールと練習 */
.rules-section {
    display: grid;
    gap: 25px;
}

.rule-box {
    background: #f8f9fa;
    border-left: 5px solid #3498db;
    border-radius: 10px;
    padding: 25px;
}

.rule-box h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 1.3rem;
}

.rule-box h3 i {
    color: #3498db;
    margin-right: 10px;
}

.rule-box ul {
    list-style: none;
    padding-left: 0;
}

.rule-box li {
    padding: 8px 0;
    color: #34495e;
    line-height: 1.6;
    padding-left: 20px;
    position: relative;
}

.rule-box li::before {
    content: "▶";
    color: #3498db;
    position: absolute;
    left: 0;
}

.practice-section h3 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 1.3rem;
}

.practice-section h3 i {
    color: #e74c3c;
    margin-right: 10px;
}

.word-practice {
    display: grid;
    gap: 15px;
}

.practice-word {
    background: white;
    border: 2px solid #ecf0f1;
    border-radius: 10px;
    padding: 20px;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 15px;
    align-items: center;
    transition: all 0.3s ease;
}

.practice-word:hover {
    border-color: #3498db;
    transform: translateX(5px);
}

.czech-word {
    font-size: 1.8rem;
    font-weight: 600;
    color: #e74c3c;
    font-family: 'Noto Serif', serif;
}

.meaning {
    color: #27ae60;
    font-weight: 500;
    text-align: right;
}

.tips-box {
    background: #e8f5e8;
    border: 2px solid #27ae60;
    border-radius: 10px;
    padding: 25px;
}

.tips-box h3 {
    color: #27ae60;
    margin-bottom: 15px;
    font-size: 1.3rem;
}

.tips-box h3 i {
    margin-right: 10px;
}

.tips-box ul {
    list-style: none;
    padding-left: 0;
}

.tips-box li {
    padding: 8px 0;
    color: #2d5a2d;
    line-height: 1.6;
    padding-left: 25px;
    position: relative;
}

.tips-box li::before {
    content: "💡";
    position: absolute;
    left: 0;
}

/* ナビゲーション */
.navigation {
    background: #f8f9fa;
    padding: 20px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid #ecf0f1;
}

.nav-btn {
    background: linear-gradient(135deg, #3498db, #2980b9);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-btn:hover {
    background: linear-gradient(135deg, #2980b9, #1f4e79);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(52, 152, 219, 0.3);
}

.nav-btn:disabled {
    background: #bdc3c7;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.slide-indicators {
    display: flex;
    gap: 10px;
}

.indicator {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: #bdc3c7;
    cursor: pointer;
    transition: all 0.3s ease;
}

.indicator.active {
    background: #3498db;
    transform: scale(1.3);
}

.indicator:hover {
    background: #7f8c8d;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }
    
    header {
        padding: 20px;
    }
    
    header h1 {
        font-size: 2rem;
    }
    
    .slide {
        padding: 20px;
        min-height: 500px;
    }
    
    .slide-content h2 {
        font-size: 1.8rem;
    }
    
    .intro-grid {
        grid-template-columns: 1fr;
    }
    
    .vowel-grid,
    .char-row {
        grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    }
    
    .practice-word {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 10px;
    }
    
    .meaning {
        text-align: center;
    }
    
    .navigation {
        padding: 15px 20px;
        flex-wrap: wrap;
        gap: 15px;
    }
    
    .nav-btn {
        padding: 10px 20px;
        font-size: 0.9rem;
    }
    
    .slide-counter {
        position: static;
        margin-top: 10px;
        display: inline-block;
    }
}

@media (max-width: 480px) {
    .vowel-grid,
    .char-row {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .czech-letter {
        font-size: 2rem;
    }
    
    .czech-letter.large {
        font-size: 1.8rem;
    }
    
    .czech-word {
        font-size: 1.5rem;
    }
}