/* 基本設定 */
:root {
    --primary-color: #3498db;
    --text-color: #333;
    --bg-color: #f4f7f6;
    --white: #ffffff;
}
body {
    font-family: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}
a {
    text-decoration: none;
    color: var(--primary-color);
}
a:hover {
    text-decoration: underline;
}

/* ヘッダー */
header {
    background-color: var(--white);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}
.header-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--text-color);
}
nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    gap: 20px;
}

/* メインレイアウト */
.container {
    max-width: 1000px;
    margin: 40px auto;
    padding: 0 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 40px;
}
main {
    flex: 2;
    min-width: 300px;
}
aside {
    flex: 1;
    min-width: 250px;
}

/* 記事カード */
.post-card {
    background: var(--white);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    margin-bottom: 30px;
    transition: transform 0.2s;
}
.post-card:hover {
    transform: translateY(-3px);
}
.post-thumbnail {
    width: 100%;
    height: 200px;
    background-color: #ddd;
    object-fit: cover;
}
.post-content {
    padding: 20px;
}
.post-category {
    font-size: 0.8rem;
    color: var(--white);
    background-color: var(--primary-color);
    padding: 3px 8px;
    border-radius: 4px;
    display: inline-block;
    margin-bottom: 10px;
}
.post-title {
    margin: 0 0 10px 0;
    font-size: 1.3rem;
}
.post-title a {
    color: var(--text-color);
}
.post-date {
    font-size: 0.85rem;
    color: #777;
    margin-bottom: 15px;
}
.post-excerpt {
    font-size: 0.95rem;
    color: #555;
    margin-bottom: 15px;
}

/* サイドバー */
.sidebar-widget {
    background: var(--white);
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    margin-bottom: 30px;
}
.sidebar-widget h3 {
    margin-top: 0;
    font-size: 1.1rem;
    border-bottom: 2px solid var(--bg-color);
    padding-bottom: 10px;
    margin-bottom: 15px;
}
.profile-img {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: #ccc;
    margin: 0 auto 15px auto;
    display: block;
}
.sidebar-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
.sidebar-list li {
    margin-bottom: 10px;
    border-bottom: 1px dashed #eee;
    padding-bottom: 5px;
}

/* フッター */
footer {
    background-color: #2c3e50;
    color: var(--white);
    text-align: center;
    padding: 20px 0;
    margin-top: 40px;
}

/* レスポンシブ対応 (スマホ向け) */
@media (max-width: 768px) {
    .header-container {
        flex-direction: column;
        gap: 10px;
    }
    .container {
        flex-direction: column;
    }
}