:root {
    --primary-color: #003366;
    /* Deep Navy */
    --secondary-color: #f4f4f4;
    /* Light Gray */
    --accent-color: #c5a059;
    /* Gold/Bronze */
    --text-color: #333333;
    --light-text: #ffffff;
    --border-color: #e0e0e0;
    --font-main: 'Noto Sans JP', 'Roboto', sans-serif;
    --max-width: 1200px;
    --header-height: 90px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', 'Noto Sans JP', sans-serif;
    color: var(--text-color);
    line-height: 1.6;
    background-color: #fff;
    padding-top: var(--header-height);
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

h3 {
    color: var(--primary-color);
    margin-top: 40px;
    margin-bottom: 20px;
}


/* Utilities */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: 80px 0;
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 40px;
    color: var(--primary-color);
    position: relative;
    display: inline-block;
    left: 50%;
    transform: translateX(-50%);
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background-color: var(--accent-color);
    margin: 15px auto 0;
}

.section-desc {
    text-align: center;
    margin-bottom: 60px;
    font-size: 1.1rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.bg-light {
    background-color: var(--secondary-color);
}

.text-center {
    text-align: center;
}

.mt-2 {
    margin-top: 10px;
}

.mt-4 {
    margin-top: 20px;
}

.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 4px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary {
    background-color: var(--accent-color);
    color: #fff;
}

.btn-primary:hover {
    background-color: #b08d4b;
}

.btn-outline {
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: #fff;
}

/* Header */
.header {
    background: linear-gradient(135deg, #003366 0%, #001f3f 100%);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    height: var(--header-height);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 15px;
    text-decoration: none;
}

.logo-img {
    height: 60px;
    width: auto;
}

.logo-text {
    display: flex;
    flex-direction: column;
}

.logo-main {
    font-size: 1.5rem;
    font-weight: 700;
    color: #ffffff;
    line-height: 1.2;
}

.logo-sub {
    font-size: 0.8rem;
    color: #e0e0e0;
}

.nav-list {
    display: flex;
    gap: 30px;
}

.nav-link {
    font-weight: 500;
    color: #ffffff;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--accent-color);
    transition: width 0.3s ease;
}

.nav-link:hover::after {
    width: 100%;
}

.lang-item {
    display: flex;
    align-items: center;
    gap: 5px;
    margin-left: 20px;
}

.lang-link {
    font-size: 0.9rem;
    font-weight: 700;
    color: #aaa;
    transition: color 0.3s ease;
}

.lang-link.active {
    color: #ffffff;
}

.lang-link:hover {
    color: var(--accent-color);
}

.lang-sep {
    color: #aaa;
    font-size: 0.9rem;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
}

.bar {
    display: block;
    width: 25px;
    height: 3px;
    margin-bottom: 6px;
    background-color: #fff;
    line-height: 1.2;
    transition: all 0.3s ease;
}

.mobile-menu-btn.active .bar {
    background-color: var(--text-color);
}

/* Hero Section */
.hero {
    position: relative;
    height: 100vh;
    min-height: 600px;
    overflow: hidden;
    margin-top: -90px;
    /* Counteract header padding */
    padding-top: 90px;
    background-color: #000;
    /* Fallback */
}

.hero-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    opacity: 0;
    animation: slideShow 25s infinite;
    display: flex;
    align-items: center;
    justify-content: center;
}

.hero-slide:nth-child(1) {
    background-image: url('images/hero-bg.png');
    animation-delay: 0s;
}

.hero-slide:nth-child(2) {
    background-image: url('images/hero-bg-4.png');
    animation-delay: 5s;
}

.hero-slide:nth-child(3) {
    background-image: url('images/hero-bg-5.png');
    animation-delay: 10s;
}

.hero-slide:nth-child(4) {
    background-image: url('images/hero-bg-6.png');
    animation-delay: 15s;
}

.hero-slide:nth-child(5) {
    background-image: url('images/hero-bg-7.png');
    animation-delay: 20s;
}

@keyframes slideShow {
    0% {
        opacity: 0;
        transform: scale(1);
        z-index: 1;
    }

    4% {
        opacity: 1;
        z-index: 2;
    }

    20% {
        opacity: 1;
        z-index: 2;
    }

    24% {
        opacity: 0;
        transform: scale(1.05);
        z-index: 1;
    }

    100% {
        opacity: 0;
        z-index: 0;
    }
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    color: #fff;
    width: 100%;
    padding: 0 20px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 40px;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

/* News Section */
.news-list {
    display: flex;
    flex-direction: column;
}

.news-item {
    display: flex;
    gap: 20px;
    padding: 20px 0;
    border-bottom: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.news-date {
    min-width: 120px;
    font-weight: 500;
    color: #666;
}

.news-content {
    flex: 1;
}

.news-tag {
    display: inline-block;
    background-color: var(--primary-color);
    color: #fff;
    font-size: 0.8rem;
    padding: 2px 8px;
    border-radius: 2px;
    margin-right: 10px;
    margin-bottom: 5px;
}

.news-title {
    font-size: 1.1rem;
    font-weight: 500;
    display: inline;
}

/* Research Section */
.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.card {
    background: #fff;
    padding: 40px 30px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease;
    text-align: center;
}

.card:hover {
    transform: translateY(-10px);
}

.card-icon {
    font-size: 3rem;
    margin-bottom: 20px;
}

.card-title {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: var(--primary-color);
}

/* Members Section */
.members-group {
    margin-bottom: 50px;
}

.members-role {
    font-size: 1.8rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 10px;
    margin-bottom: 30px;
    color: var(--primary-color);
}

.member-card {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 20px;
}

.member-name {
    font-size: 1.4rem;
    margin-bottom: 5px;
}

.member-name span {
    font-size: 1rem;
    color: #666;
    margin-left: 10px;
    font-weight: 400;
}

.members-list {
    list-style: disc;
    padding-left: 20px;
}

.members-list li {
    margin-bottom: 10px;
    font-size: 1.1rem;
}

/* Publications Section */
.publication-list li {
    margin-bottom: 20px;
    padding-bottom: 20px;
    border-bottom: 1px dashed var(--border-color);
}

.pub-year {
    padding: 30px 0;
    text-align: center;
}

.copyright {
    font-size: 0.9rem;
    opacity: 0.8;
    text-align: center;
}

/* Access Section */
.access-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: center;
}

.access-map {
    width: 100%;
    height: 300px;
}

/* Footer */
.footer {
    background-color: var(--primary-color);
    color: #fff;
    padding: 30px 0;
    text-align: center;
}

.copyright {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Responsive */
@media (max-width: 768px) {
    .header-container {
        padding: 0 20px;
    }

    .mobile-menu-btn {
        display: block;
        z-index: 1001;
    }

    .nav {
        position: fixed;
        top: 0;
        right: -100%;
        width: 70%;
        height: 100vh;
        background-color: #fff;
        box-shadow: -5px 0 15px rgba(0, 0, 0, 0.1);
        transition: right 0.3s ease;
        padding-top: 80px;
    }

    .nav.active {
        right: 0;
    }

    .nav-list {
        flex-direction: column;
        align-items: center;
        gap: 20px;
    }

    .nav-link {
        color: var(--text-color);
        /* Dark text for mobile menu */
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .news-item {
        flex-direction: column;
    }

    .news-date {
        margin-bottom: 5px;
    }

    .access-grid {
        grid-template-columns: 1fr;
    }
}