/* ==========================================================================
   リセット・基本設定
   ========================================================================== */

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    font-family: 'Meiryo', 'Hiragino Kaku Gothic Pro', 'MS PGothic', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
}

/* ==========================================================================
   レイアウト
   ========================================================================== */

/* コンテナ */
#container {
    max-width: 1200px;
    margin: 0 auto;
    border: 1px solid #000;
    background-color: #fff;
}

/* ヘッダー */
#header {
    padding: 20px;
    border-bottom: 1px solid #000;
    text-align: center;
}

/* メインコンテンツ */
#contents {
    padding: 20px;
}

/* フッター */
footer {
    background: #4b64b0;
    color: #fff;
    text-align: center;
    padding: 20px;
    margin-top: 40px;
}

/* ==========================================================================
   見出し
   ========================================================================== */

/* ページタイトル */
h1 {
    margin: 0 0 20px 0;
    font-size: 1.5rem;
    line-height: 1.4;
}

h1 img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 0 auto 10px auto;
}

.session-title {
    display: block;
    color: #003366;
    font-weight: bold;
    margin-top: 10px;
}

/* セクション見出し */
h2 {
    color: #fff;
    background: #6c8ffc;
    font-size: 1.2rem;
    margin: 30px 0 20px 0;
    padding: 15px;
    box-shadow: 1px 3px 7px 0 rgba(102, 102, 102, 0.3);
    border-top: 3px solid #FFD412;
    border-radius: 5px;
}

/* セッション見出し */
h3 {
    color: #2c2521;
    font-size: 1.1rem;
    margin: 20px 0 15px 0;
    padding: 10px 0 10px 15px;
    border-left: 10px solid #000;
    border-bottom: 1px solid #000;
    line-height: 1.4;
}

/* ==========================================================================
   ナビゲーション
   ========================================================================== */

.nav {
    margin: 20px auto;
    background: #4b64b0;
    border-top: 2px solid #84aed2;
    border-bottom: 2px solid #2c5170;
    border-radius: 5px;
    overflow: hidden;
}

.nav-list {
    margin: 0;
    padding: 0;
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

.nav-list li {
    flex: 1;
    min-width: 80px;
}

.nav-list li a {
    display: block;
    padding: 12px 8px;
    text-decoration: none;
    font-weight: bold;
    color: #fff;
    text-align: center;
    border-right: 1px solid #2c5170;
    transition: background-color 0.3s ease;
}

.nav-list li:last-child a {
    border-right: none;
}

.nav-list li a:hover {
    background-color: #5e91bd;
    color: #FFD412;
}

/* ==========================================================================
   セッション
   ========================================================================== */

.session-item {
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 1px dashed #ccc;
}

.session-item:last-child {
    border-bottom: none;
}

/* セッション番号 */
.session-number {
    width: 200px;
    margin-bottom: 15px;
}

.session-number span {
    display: inline-block;
    width: 4em;
    color: #FFD412;
    background: #4b64b0;
    font-weight: bold;
    font-size: 1.25rem;
    text-align: center;
    padding: 8px 0;
    border-radius: 4px;
}

/* オーガナイザーリスト */
.organizers {
    margin: 15px 0;
    padding-left: 20px;
}

.organizers li {
    list-style: square;
    margin-bottom: 5px;
    color: #666;
}

.organizers a {
    color: #4b64b0;
    text-decoration: none;
}

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

/* スコープ */
.scope {
    color: #666;
    margin: 15px 0;
    line-height: 1.6;
}

/* TOPリンク */
.top-link {
    text-align: right;
    margin-top: 20px;
}

.top-link a {
    color: #4b64b0;
    text-decoration: none;
    font-size: 0.9rem;
}

.top-link a:hover {
    text-decoration: underline;
}

/* ==========================================================================
   レスポンシブデザイン
   ========================================================================== */

/* タブレット */
@media screen and (max-width: 768px) {
    #container {
        border: none;
        margin: 0;
    }
    
    #header,
    #contents {
        padding: 15px;
    }
    
    h1 {
        font-size: 1.3rem;
    }
    
    h2 {
        font-size: 1.1rem;
        padding: 12px;
    }
    
    h3 {
        font-size: 1rem;
        padding: 8px 0 8px 12px;
        border-left-width: 6px;
    }
    
    .nav-list {
        flex-direction: column;
    }
    
    .nav-list li {
        flex: none;
    }
    
    .nav-list li a {
        border-right: none;
        border-bottom: 1px solid #2c5170;
    }
    
    .nav-list li:last-child a {
        border-bottom: none;
    }
    
    .session-number {
        width: 150px;
    }
    
    .session-number span {
        font-size: 1.1rem;
        padding: 6px 0;
    }
}

/* スマートフォン */
@media screen and (max-width: 480px) {
    #header,
    #contents {
        padding: 10px;
    }
    
    h1 {
        font-size: 1.2rem;
    }
    
    h2 {
        font-size: 1rem;
        padding: 10px;
        margin: 20px 0 15px 0;
    }
    
    h3 {
        font-size: 0.95rem;
        padding: 6px 0 6px 10px;
        border-left-width: 5px;
    }
    
    .nav-list li a {
        padding: 10px 6px;
        font-size: 0.9rem;
    }
    
    .session-number {
        width: 120px;
    }
    
    .session-number span {
        font-size: 1rem;
        padding: 5px 0;
    }
    
    .organizers {
        padding-left: 15px;
    }
    
    .scope {
        font-size: 0.9rem;
    }
    
    footer {
        padding: 15px 10px;
        font-size: 0.9rem;
    }
}

/* 極小画面 */
@media screen and (max-width: 320px) {
    .nav-list li a {
        padding: 8px 4px;
        font-size: 0.8rem;
    }
    
    .session-number span {
        font-size: 0.9rem;
    }
}