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

body {
    font-family: 'Segoe UI', 'メイリオ', Meiryo, sans-serif;
    line-height: 1.8;
    color: #333;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    padding: 20px;
    padding-top: 90px; /* Header height */
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.1);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 60px 40px;
    text-align: center;
}

h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
    font-weight: 700;
}

.subtitle {
    font-size: 1.1em;
    opacity: 0.9;
}

.content {
    padding: 50px 40px;
}

h2 {
    font-size: 1.8em;
    color: #667eea;
    margin: 40px 0 20px 0;
    padding-bottom: 10px;
    border-bottom: 3px solid #667eea;
}

h3 {
    font-size: 1.4em;
    color: #764ba2;
    margin: 30px 0 15px 0;
}

p {
    margin-bottom: 20px;
    text-align: justify;
}

ul {
    margin-left: 20px;
    margin-bottom: 20px;
}

li {
    margin-bottom: 10px;
}

.card {
    background: #f8f9fa;
    border-left: 4px solid #667eea;
    padding: 20px;
    margin: 20px 0;
    border-radius: 5px;
}

.highlight {
    background: linear-gradient(transparent 60%, #ffd93d 60%);
    padding: 2px 4px;
    font-weight: 600;
}

footer {
    background: #2c3e50;
    color: white;
    text-align: center;
    padding: 30px;
    font-size: 0.9em;
}

@media (max-width: 768px) {
    h1 {
        font-size: 2em;
    }
    
    .content {
        padding: 30px 20px;
    }
    
    header {
        padding: 40px 20px;
    }
}