.ouyouSection {
    background-color: #f9f9f9b5;
}

/* ページタイトル */
.ouyouTitle {
    margin: 30px auto;
    padding: 40px 15px 0;
    text-align: center;
    font-size: 2rem;
}

/* ページ概要 */
.ouyouIntroduce {
    max-width: 1100px;
    margin: 0 auto 40px;
    padding: 0 90px 60px;
    box-sizing: border-box;
}

/* 記事一覧：PC・タブレットは2列 */
.ouyouArticleBox {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    align-items: stretch;
    gap: 30px;
    width: 100%;
    max-width: 1400px;
    margin: 50px auto;
    padding: 0 20px;
    box-sizing: border-box;
}

/* 記事カード */
.ouyouCard {
    display: flex;
    flex-direction: column;
    gap: 20px;
    min-width: 0;
    padding: 24px;
    box-sizing: border-box;
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

/* 講義番号とタイトル */
.ouyouCardHeading {
    display: flex;
    align-items: center;
    gap: 18px;
    min-width: 0;
    padding-bottom: 15px;
    border-bottom: 1px solid #333;
}

/* 六角形の講義番号 */
.ouyouCardNumber {
    display: flex;
    flex: 0 0 76px;
    align-items: center;
    justify-content: center;
    width: 76px;
    height: 70px;
    box-sizing: border-box;
    background: linear-gradient(135deg, #f47721, #c45116);
    clip-path: polygon(25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%, 0% 50%);
    color: #fff;
    font-size: 25px;
    font-weight: bold;
    white-space: nowrap;
    font-family: Verdana Bold Italic;
}

/* 講義タイトル */
.ouyouCardTitle {
    flex: 1;
    min-width: 0;
    margin: 0;
    font-size: 25px;
    line-height: 1.5;
    overflow-wrap: anywhere;
}

/* 説明文と画像 */
.ouyouCardMain {
    display: grid;
    grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
    align-items: stretch;
    gap: 18px;
    min-width: 0;
}

/* 説明文・難易度 */
.ouyouCardContent {
    display: flex;
    flex-direction: column;
    min-width: 0;
}

.ouyouDescription {
    display: -webkit-box;
    -webkit-box-orient: vertical;
    -webkit-line-clamp: 4;
    line-clamp: 4;
    overflow: hidden;
    margin: 0 0 18px;
    font-size: 1rem;
    line-height: 1.7;
    overflow-wrap: anywhere;
}

/* 難易度 */
.ouyouDifficulty {
    margin: auto 0 0;
    font-size: 1.2rem;
    line-height: 1.5;
    overflow-wrap: anywhere;
}

.ouyouDifficultyLabel {
    margin-right: 5px;
}

.ouyouStars {
    white-space: nowrap;
    letter-spacing: 1px;
}

/* サムネイル画像 */
.ouyouCardImage {
    min-width: 0;
    min-height: 180px;
    overflow: hidden;
    background: #eee;
}

.ouyouCardImage img {
    display: block;
    width: 100%;
    height: 100%;
    min-height: 180px;
    object-fit: contain;
}

.ouyouImageError {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-height: 180px;
    padding: 20px;
    box-sizing: border-box;
    color: #555;
    text-align: center;
}

/* ボタン：横並び */
.ouyouCardButtons {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 14px;
    margin-top: auto;
}

.ouyouButton {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-width: 0;
    min-height: 60px;
    padding: 10px 12px;
    box-sizing: border-box;
    border: 1px solid #888;
    border-radius: 12px;
    font-family: inherit;
    font-size: 1.1rem;
    line-height: 1.4;
    text-align: center;
    text-decoration: none;
    cursor: pointer;
    transition: background-color 0.2s;
}

.ouyouLectureButton {
    background-color: #e4f1dc;
    border-color: #8ab76d;
    color: #222;
}

.ouyouLectureButton:hover {
    background-color: #d4e8c8;
}

.ouyouPracticeButton {
    background-color: #d9d9d9;
    border-color: #111;
    color: #222;
}

.ouyouPracticeButton:hover:not(:disabled) {
    background-color: #c9c9c9;
}

.ouyouPracticeButton:disabled {
    background-color: #d9d9d9;
    border-color: #888;
    color: #666;
    cursor: not-allowed;
    opacity: 1;
}

/* 記事データの読み込みエラー */
.ouyouNoArticles {
    grid-column: 1 / -1;
    padding: 30px;
    background-color: #f5f5f5;
    border: 1px solid #ddd;
    border-radius: 8px;
    line-height: 1.8;
    text-align: center;
    overflow-wrap: anywhere;
}

/* ========================================
   タブレット：600px以上900px未満
   2列を維持しつつ、余白と文字を少し縮小
   ======================================== */
@media screen and (min-width: 600px) and (max-width: 899.98px) {

    .ouyouTitle {
        font-size: 1.8rem;
        padding: 90px 0 0px;
    }

    .ouyouIntroduce {
        padding: 0 60px 40px;
    }


    .ouyouArticleBox {
        gap: 20px;
        padding: 0 16px;
        margin: 35px auto;
    }

    .ouyouCard {
        gap: 16px;
        padding: 16px;
    }

    .ouyouCardHeading {
        gap: 10px;
        padding-bottom: 12px;
    }

    .ouyouCardNumber {
        flex-basis: 58px;
        width: 58px;
        height: 54px;
        font-size: 20px;
    }

    .ouyouCardTitle {
        font-size: 1.15rem;
    }

    .ouyouCardMain {
        grid-template-columns: minmax(0, 1fr);
        gap: 14px;
    }

    .ouyouDescription {
        -webkit-line-clamp: 4;
        line-clamp: 4;
        margin-bottom: 12px;
        font-size: 0.95rem;
    }

    .ouyouDifficulty {
        margin-top: 0;
        font-size: 1.05rem;
    }

    .ouyouCardImage {
        min-height: 0;
        aspect-ratio: 16 / 9;
    }

    .ouyouCardImage img {
        height: 100%;
        min-height: 0;
    }

    .ouyouImageError {
        min-height: 120px;
    }

    .ouyouCardButtons {
        gap: 8px;
    }

    .ouyouButton {
        min-height: 52px;
        padding: 8px 5px;
        font-size: 0.95rem;
    }
}

/* ========================================
   スマートフォン：600px未満
   記事カードを1列、説明文と画像を縦並び
   ======================================== */
@media screen and (max-width: 599.98px) {
    .ouyouTitle {
        font-size: 1.5rem;
        padding: 90px 0 10px;
    }

    .ouyouIntroduce {
        margin-bottom: 30px;
        padding: 0 40px 40px;
    }

    .ouyouArticleBox {
        grid-template-columns: minmax(0, 1fr);
        gap: 22px;
        margin: 30px auto;
        padding: 0 12px;
    }

    .ouyouCard {
        gap: 16px;
        padding: 16px;
    }

    .ouyouCardHeading {
        gap: 12px;
        padding-bottom: 12px;
    }

    .ouyouCardNumber {
        flex-basis: 64px;
        width: 64px;
        height: 59px;
        font-size: 20px
    }

    .ouyouCardTitle {
        font-size: 1.2rem;
    }

    .ouyouCardMain {
        grid-template-columns: minmax(0, 1fr);
        gap: 14px;
    }

    .ouyouDescription {
        -webkit-line-clamp: 4;
        line-clamp: 4;
        margin-bottom: 12px;
        font-size: 1rem;
    }

    .ouyouDifficulty {
        margin-top: 0;
        font-size: 1.15rem;
    }

    .ouyouCardImage {
        min-height: 0;
        aspect-ratio: 16 / 9;
    }

    .ouyouCardImage img {
        width: 100%;
        height: 100%;
        min-height: 0;
        object-fit: contain;
    }

    .ouyouImageError {
        min-height: 140px;
    }

    .ouyouCardButtons {
        gap: 10px;
    }

    .ouyouButton {
        min-height: 54px;
        padding: 8px 5px;
        font-size: 1rem;
    }
}

/* 小型スマートフォン */
@media screen and (max-width: 380px) {
    .ouyouCard {
        padding: 12px;
    }

    .ouyouCardNumber {
        flex-basis: 54px;
        width: 54px;
        height: 50px;
        font-size: 20px
    }

    .ouyouCardTitle {
        font-size: 1.05rem;
    }

    .ouyouCardButtons {
        gap: 7px;
    }

    .ouyouButton {
        font-size: 0.9rem;
    }
}