/* --- Basic Setup --- */
body {
    margin: 0;
    font-family: 'Roboto', sans-serif;
    line-height: 1.5;
    background-color: #ffffff;
    color: #333;
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* --- Header --- */
header {
    padding-bottom: 20px;
    border-bottom: 1px solid #ddd;
}

/* 旧 .banner img 関連のスタイルは削除 */
/* header img {
    max-width: 960px;
    width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
} */

/* 新しいヘッダーコンテンツのレイアウト */
.header-content {
    display: flex; /* Flexboxを使って横並び */
    align-items: center; /* 垂直方向中央揃え */
    padding: 20px 0;
    margin-bottom: 20px; /* ナビゲーションとの間にスペース */
}

.header-logo {
    width: 240px; /* ロゴのサイズを調整 */
    height: 180px;
    object-fit: contain; /* アスペクト比を保ちつつ収める */
    margin-right: 30px;
    flex-shrink: 0; /* 縮小しない */
}

.header-info {
    flex-grow: 1; /* 残りのスペースを埋める */
}

.header-info h1 {
    font-size: 2.2em; /* 学会名のフォントサイズを調整 */
    color: #004a99;
    margin: 0 0 10px 0; /* マージンを調整 */
    text-align: left; /* 左寄せ */
    line-height: 1.2;
}

.header-info p {
    font-size: 1em;
    color: #555;
    margin: 5px 0;
    text-align: left; /* 左寄せ */
}


/* --- Navigation --- */
nav {
    position: relative;
}

.hamburger {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 10px;
    z-index: 1001;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: #004a99;
    margin: 3px 0;
    transition: 0.3s;
    display: block;
}

.hamburger.active span:nth-child(1) {
    transform: rotate(-45deg) translate(-5px, 6px);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: rotate(45deg) translate(-5px, -6px);
}

nav .nav-menu {
    list-style-type: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
    background-color: #004a99;
    border-radius: 5px;
}

nav li {
    margin: 0;
}

nav a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 20px;
    text-decoration: none;
    font-weight: bold;
    transition: background-color 0.3s;
}

nav a:hover {
    background-color: #005cb3;
}

nav a.active {
    background-color: #003366;
}


/* --- Main Content --- */
main {
    padding: 20px 0;
}

section {
    margin-bottom: 40px;
}

h2 {
    font-size: 2em;
    color: #004a99;
    border-bottom: 2px solid #004a99;
    padding-bottom: 10px;
    margin-bottom: 20px;
}

/* Definition List for Conference Info */
.overview-list {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: 10px 20px;
}

.overview-list dt {
    font-weight: bold;
    color: #555;
}

.overview-list dd {
    margin: 0;
}

/* Topics List */
ul {
    list-style-type: none;
    padding-left: 0;
}

li {
    margin-bottom: 8px;
    padding-left: 5px;
}

/* --- Footer --- */
footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 20px 0;
    margin-top: 40px;
}

/* --- Google Map Container --- */
.map-container {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 Aspect Ratio */
    height: 0;
    overflow: hidden;
    max-width: 100%;
    margin: 20px 0;
}

.map-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

/* --- Responsive Design for Mobile --- */
@media (max-width: 700px) {
    .header-content {
        flex-direction: column; /* スマートフォンでは縦並び */
        text-align: center;
    }

    .header-logo {
        margin-right: 0; /* 右マージンをリセット */
        margin-bottom: 20px; /* 下にマージンを追加 */
    }

    .header-info h1 {
        font-size: 1.8em; /* スマートフォンではフォントサイズを小さく */
        text-align: center;
        line-height: 1.2;
    }

    .header-info p {
        text-align: center;
    }

    h2 {
        font-size: 1.5em;
    }

    /* Show hamburger menu */
    .hamburger {
        display: flex;
        position: absolute;
        top: 10px;
        right: 20px;
    }

    /* Hide navigation by default on mobile */
    nav .nav-menu {
        position: fixed;
        top: 0;
        left: -100%;
        width: 100%;
        height: 100vh;
        background-color: #004a99;
        flex-direction: column;
        justify-content: start;
        align-items: center;
        transition: left 0.3s ease;
        z-index: 1000;
        padding-top: 60px;
        border-radius: 0;
    }

    /* Show navigation when active */
    nav .nav-menu.active {
        left: 0;
    }

    nav li {
        margin: 10px 0;
        width: 80%;
    }

    nav a {
        padding: 15px;
        font-size: 1.2em;
        border-bottom: 1px solid #005cb3;
        width: 100%;
        text-align: center;
    }

    .overview-list {
        grid-template-columns: 1fr; /* Stack definition list on mobile */
    }
    
    .overview-list dt {
        border-top: 1px solid #ddd;
        padding-top: 10px;
    }

    .overview-list dt:first-of-type {
        border-top: none;
        padding-top: 0;
    }
}