/* === Reset & Base (Mobile First: 375px) === */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Yu Gothic', YuGothic, Meiryo, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f0f4f5;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 12px;
}

/* === Header === */
header {
    background-color: #fff;
    padding: 16px;
    border-radius: 10px;
    margin-bottom: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

h1 {
    color: #42b8c3;
    font-size: 20px;
}

.lang-switch {
    display: flex;
    gap: 8px;
}

.lang-switch a {
    padding: 6px 14px;
    background-color: #f0f4f5;
    color: #333;
    border-radius: 20px;
    text-decoration: none;
    font-size: 13px;
    font-weight: 600;
    transition: all 0.2s;
}

.lang-switch a:hover {
    background-color: #d1ecee;
}

.lang-switch a.active {
    background-color: #42b8c3;
    color: #fff;
}

/* === Content === */
.content {
    background-color: #fff;
    padding: 16px;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

.content .updated {
    font-size: 13px;
    color: #666;
    margin-bottom: 16px;
}

h2 {
    color: #42b8c3;
    font-size: 18px;
    margin-top: 28px;
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 2px solid #e0f5f6;
}

h2:first-of-type {
    margin-top: 0;
}

h3 {
    color: #2c3e50;
    font-size: 15px;
    margin-top: 20px;
    margin-bottom: 8px;
}

.content p {
    margin-bottom: 12px;
    font-size: 14px;
}

.content ul, .content ol {
    margin: 10px 0 10px 20px;
    padding-left: 0;
}

.content li {
    margin-bottom: 6px;
    font-size: 14px;
}

.content a {
    color: #42b8c3;
    text-decoration: none;
}

.content a:hover {
    text-decoration: underline;
}

.content strong {
    color: #2c3e50;
}

/* === Tablet: 768px === */
@media (min-width: 768px) {
    .container {
        padding: 20px;
    }

    header {
        padding: 24px;
        border-radius: 12px;
        margin-bottom: 16px;
    }

    h1 {
        font-size: 24px;
    }

    .lang-switch a {
        padding: 8px 16px;
        font-size: 14px;
    }

    .content {
        padding: 24px;
        border-radius: 12px;
    }

    h2 {
        font-size: 20px;
        margin-top: 32px;
        margin-bottom: 16px;
    }

    h3 {
        font-size: 16px;
    }

    .content p, .content li {
        font-size: 15px;
    }

    .content .updated {
        font-size: 14px;
    }
}

/* === PC: 1024px === */
@media (min-width: 1024px) {
    .container {
        padding: 30px;
    }

    header {
        padding: 28px 32px;
        margin-bottom: 20px;
    }

    h1 {
        font-size: 26px;
    }

    .lang-switch a {
        padding: 8px 20px;
        font-size: 14px;
    }

    .content {
        padding: 32px;
    }

    h2 {
        font-size: 22px;
        margin-top: 36px;
        margin-bottom: 18px;
    }

    h3 {
        font-size: 17px;
    }

    .content p, .content li {
        font-size: 15px;
    }
}