@font-face {
    font-family: 'Satoshi';
    font-weight: 400;
    src: url('../font/Satoshi.woff2') format('woff2');
}

@font-face {
    font-family: 'GeneralSans';
    font-weight: 400;
    src: url('../font/GeneralSans-Regular.woff2') format('woff2');
}

/* カラーテーマの定義 */
:root {
    --vh: 1vh;
    --primary-color: #e9e9e9;
    --background-color: #1a1a2e;
    --accent-color: #4eb3ff;
    --research-item-bg: #2a2a3e;
    --research-item-shadow: rgba(255, 255, 255, 0.1);
}

/* 全体のリセットと基本スタイル */
html {
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
    min-width: 350px;
    overflow-x: hidden;
    overflow-y: scroll;
    scroll-behavior: smooth;
}

body {
    margin: 0;
    padding: 0;
    width: 100vw;
    background-color: var(--background-color);
    font-family: 'Satoshi', sans-serif;
    color: var(--primary-color);
    -webkit-font-smoothing: antialiased;
    transition: background-color 0.3s ease, color 0.3s ease;
    position: relative;
    z-index: 1;
}

* {
    font-size: 18px;
    line-height: 1.6;
    font-weight: normal;
    box-sizing: border-box;
}

/* コンテナ */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* ヒーローセクション */
.hero {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    text-align: center;
    position: relative;
}

.title {
    font-size: 3rem;
    line-height: 1.2;
    font-family: 'GeneralSans', sans-serif;
    margin: 0;
}

.subtitle {
    font-size: 1rem;
    line-height: 1.4;
    margin-top: 1rem;
    color: var(--primary-color);
}

.links {
    margin-top: 2rem;
    display: flex;
    justify-content: center;
    gap: 1rem;
}

.links a {
    text-decoration: none;
    font-size: 0.9rem;
    color: var(--primary-color);
    transition: color 0.3s ease, border-color 0.3s ease;
    padding: 0.5rem 1rem;
    border: 1px solid var(--primary-color);
    border-radius: 20px;
}

.links a:hover {
    color: var(--accent-color);
    border-color: var(--accent-color);
}

/* 研究セクション */
.research-section {
    padding: 4rem 0;
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.research-item {
    background-color: var(--research-item-bg);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 4px 6px var(--research-item-shadow);
    transition: transform 0.3s ease, background-color 0.3s ease, box-shadow 0.3s ease;
}

.research-item:hover {
    transform: translateY(-5px);
}

.research-item h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--accent-color);
}

.section-title {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 2rem;
}

/* ソーシャルリンク */
.social-links {
    position: fixed;
    bottom: 20px;
    right: 20px;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    z-index: 100;
}

.social-links a {
    text-decoration: none;
    font-size: 2rem;
    color: var(--primary-color);
    transition: color 0.3s ease;
}

.social-links a:hover {
    color: var(--accent-color);
}

/* particles.js container */
#particles-js {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

/* 言語切り替えボタンのスタイル */
.language-switcher {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1000;
}

.language-switcher button {
    background-color: var(--primary-color);
    color: var(--background-color);
    border: none;
    padding: 5px 10px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 14px;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.language-switcher button:hover {
    background-color: var(--accent-color);
    color: var(--primary-color);
}

@media (max-width: 768px) {
    .title {
        font-size: 2.5rem;
    }

    .links {
        flex-direction: column;
    }

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

    .social-links {
        bottom: 10px;
        right: 10px;
        flex-direction: row;
        gap: 0.5rem;
    }
}