:root {
    --primary-color: #003366;
    --accent-color: #00fa9a;
    --text-color: #333;
    --white: #ffffff;
    --light-bg: #f4f7f6;
}

/* 全体リセット */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    overflow-x: hidden;
    width: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    color: var(--text-color);
    line-height: 1.6;
}

/* ヘッダー */
header {
    background: rgba(255, 255, 255, 0.98);
    padding: 15px 5%;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.2rem;
    font-weight: bold;
    z-index: 1001;
}

.logo span {
    color: var(--primary-color);
}

/* メニューボタン設定 */
.menu-trigger {
    position: relative;
    width: 30px;
    height: 24px;
    background: none;
    border: none;
    cursor: pointer;
    z-index: 9999; /* 常に最前面 */
    display: none; /* デフォルト非表示 */
}

.menu-trigger span {
    display: block;
    position: absolute;
    width: 100%;
    height: 2px;
    background: var(--primary-color);
    transition: all 0.4s;
}

.menu-trigger span:nth-child(1) { top: 0; }
.menu-trigger span:nth-child(2) { top: 11px; }
.menu-trigger span:nth-child(3) { bottom: 0; }

/* ボタン活性化（×印） */
.menu-trigger.is-active span { background: #fff !important; }
.menu-trigger.is-active span:nth-child(1) { transform: translateY(11px) rotate(-45deg); }
.menu-trigger.is-active span:nth-child(2) { opacity: 0; }
.menu-trigger.is-active span:nth-child(3) { transform: translateY(-11px) rotate(45deg); }

/* ナビゲーション共通 */
.nav-list {
    display: flex;
    list-style: none;
    align-items: center;
}

.nav-list li {
    margin-left: 30px;
}

.nav-list a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
}

.nav-btn {
    background: var(--primary-color);
    color: white !important;
    padding: 8px 20px;
    border-radius: 5px;
}

/* --- モバイル設定 (768px以下) --- */
@media screen and (max-width: 768px) {
    .menu-trigger {
        display: block; /* スマホのみ表示 */
    }

    .nav-overlay {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100vh;
        background: rgba(0, 51, 102, 0.98);
        z-index: 9000;
        display: none; /* 初期は消す */
        flex-direction: column;
        align-items: center;
        justify-content: center;
    }

    .nav-overlay.is-open {
        display: flex; /* 開いた時に表示 */
    }

    .nav-list {
        flex-direction: column;
        padding: 0;
    }

    .nav-list li {
        margin: 20px 0;
    }

    .nav-list a {
        color: #ffffff !important;
        font-size: 1.8rem;
    }
}

/* ヒーローセクション */
.hero {
    height: 100vh;
    background: linear-gradient(rgba(0,51,102,0.6), rgba(0,51,102,0.6)), url('https://images.unsplash.com/photo-1518467166778-b88f373ffec7?auto=format&fit=crop&w=1500&q=80');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: white;
    padding: 0 20px;
}

.hero h1 {
    font-size: 2.2rem;
    margin-bottom: 20px;
}

@media screen and (min-width: 769px) {
    .hero h1 { font-size: 3.5rem; }
}

.btn-main {
    display: inline-block;
    padding: 15px 40px;
    background: var(--accent-color);
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    margin-top: 30px;
}

/* コンテンツ */
.container {
    padding: 80px 20px;
    max-width: 1000px;
    margin: 0 auto;
    text-align: center;
}

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

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.card {
    background: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    text-align: left;
}

footer {
    padding: 40px;
    background: var(--primary-color);
    color: white;
    text-align: center;
}