:root {
    --primary-color: #4f46e5;
    --primary-dark: #3730a3;
    --secondary-color: #06b6d4;
    --accent-color: #10b981;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-light: #f8fafc;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
}

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

/* 基本スタイル */
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-light);
}

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

/* ヘッダー */
header {
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 1rem 0;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: var(--primary-color);
}

/* ハンバーガーメニュー */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 5px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    margin: 3px 0;
    transition: 0.3s;
    border-radius: 2px;
}

.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);
}

/* モバイルメニュー */
.mobile-menu {
    display: none;
    position: fixed;
    top: 72px;
    left: 0;
    right: 0;
    background-color: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 999;
    transform: translateY(-100%);
    transition: transform 0.3s ease;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.mobile-menu.active {
    transform: translateY(0);
}

.mobile-menu ul {
    list-style: none;
    padding: 0px 20px;
    margin: 0;
}

.mobile-menu li {
    margin: 0;
    border-bottom: 1px solid var(--border-color);
}

.mobile-menu li:last-child {
    border-bottom: none;
}

.mobile-menu a {
    display: block;
    padding: 15px 0;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: color 0.3s ease;
}

.mobile-menu a:hover {
    color: var(--primary-color);
}

/* Footer */
footer {
    background: linear-gradient(135deg, var(--text-primary), #374151);
    color: white;
    padding: 3rem 0 2rem;
    text-align: center;
}

.footer-nav {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.footer-nav a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-nav a:hover {
    color: white;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hamburger {
        display: flex;
    }

    .mobile-menu {
        display: block;
    }

    .main-container {
        padding: 0 1rem;
        margin: 7rem auto 2rem;
    }

    .content {
        padding: 2rem 1.5rem;
    }

    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    h3 {
        font-size: 1.2rem;
    }
}

@media (max-width: 480px) {
    .main-container {
        margin: 6rem auto 2rem;
    }

    .content {
        padding: 1.5rem 1rem;
        border-radius: 12px;
    }

    h1 {
        font-size: 1.75rem;
    }

    h2 {
        font-size: 1.3rem;
    }

    .contact-section {
        padding: 1.5rem;
    }
}

/* ダークモード対応 */
@media (prefers-color-scheme: dark) {
    html:not(.light-mode-only) :root {
        --text-primary: #ecf0f1;
        --text-secondary: #bdc3c7;
        --background: #1a1a1a;
        --surface: #2c2c2c;
        --border-color: #444;
    }
    
    html:not(.light-mode-only) body {
        background-color: var(--background);
        color: var(--text-primary);
    }
    
    html:not(.light-mode-only) .content {
        background-color: var(--surface);
    }
    
    html:not(.light-mode-only) .header {
        background-color: var(--surface);
    }
    
    html:not(.light-mode-only) .info-box {
        background-color: rgba(66, 133, 244, 0.1);
    }
    
    html:not(.light-mode-only) .contact-section {
        background-color: rgba(255, 255, 255, 0.05);
    }
}