/* ===== ベース設定 (モダンダークテーマ) ===== */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;800&family=Noto+Sans+JP:wght@400;600;800&display=swap');

:root {
    --bg-base: #0f172a;
    /* 暗い紺色背景 */
    --bg-surface: #1e293b;
    /* 浮き上がる要素の背景 */
    --text-main: #f8fafc;
    /* メインテキスト色（白寄り） */
    --text-muted: #94a3b8;
    /* サブテキスト色（グレー） */
    --accent: #ff9970;
    --accent-hover: #ffb396;
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', 'Noto Sans JP', sans-serif;
    margin: 0;
    padding: 0;
    background-color: var(--bg-base);
    color: var(--text-main);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

b,
strong {
    color: var(--accent);
    font-weight: 800;
}

/* ===== ヘッダー (グラスモーフィズム) ===== */
header {
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-main);
    padding: 1rem 3rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    position: sticky;
    top: 0;
    z-index: 1000;
}

header h1 {
    font-size: 1.5rem;
    font-weight: 800;
    margin: 0;
    letter-spacing: 0.05em;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
    margin: 0;
    padding: 0;
}

nav a {
    color: var(--text-main);
    font-weight: 600;
    font-size: 0.95rem;
    position: relative;
    padding-bottom: 4px;
}

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

nav a:hover {
    color: var(--accent);
    text-decoration: none;
}

nav a:hover::after {
    width: 100%;
}

/* ===== セクション共通 ===== */
.section {
    padding: 4rem 2rem;
    max-width: 900px;
    margin: 0 auto;
}

.section h2 {
    font-size: 1.8rem;
    border-left: 5px solid var(--accent);
    padding-left: 1rem;
    margin-bottom: 1.5rem;
    color: var(--text-main);
    font-weight: 800;
}

.section p {
    color: var(--text-muted);
    font-size: 1.05rem;
}

.section ul {
    list-style: none;
    padding-left: 0;
}

.section ul li {
    padding: 0.5rem 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    color: var(--text-muted);
}

.section ul li::before {
    content: '▹';
    color: var(--accent);
    margin-right: 10px;
    font-weight: bold;
}

/* ===== ボタン ===== */
.button {
    display: inline-block;
    background-color: var(--accent);
    color: #1a1a1a;
    padding: 0.8rem 2rem;
    border-radius: 8px;
    font-weight: 800;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    box-shadow: 0 4px 15px rgba(255, 153, 112, 0.3);
}

.button:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 153, 112, 0.4);
    text-decoration: none;
    color: #1a1a1a;
}

/* ===== フッター ===== */
footer {
    background-color: #0b1120;
    color: var(--text-muted);
    text-align: center;
    padding: 2rem;
    margin-top: 4rem;
    font-size: 0.9rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

/* ===== ハンバーガーメニュー ===== */
.hamburger-btn {
    display: none;
    flex-direction: column;
    justify-content: space-around;
    width: 30px;
    height: 25px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1001;
}

.hamburger-btn span {
    width: 30px;
    height: 3px;
    background: var(--text-main);
    border-radius: 10px;
    transition: all 0.3s linear;
    transform-origin: 1px;
}

.hamburger-btn.active span:nth-child(1) {
    transform: rotate(45deg);
}

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

.hamburger-btn.active span:nth-child(3) {
    transform: rotate(-45deg);
}

/* ===== チャートエリア ===== */
.chart-container {
    position: relative;
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
}

/* ===== フェードインアニメーション ===== */
.section {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.8s cubic-bezier(0.25, 1, 0.5, 1);
}

.section.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== レスポンシブ対応 ===== */
@media (max-width: 768px) {
    header {
        flex-direction: row;
        align-items: center;
        padding: 1rem;
        position: relative;
    }

    .hamburger-btn {
        display: flex;
    }

    nav {
        display: none;
        width: 100%;
        position: absolute;
        top: 100%;
        left: 0;
        background: rgba(15, 23, 42, 0.95);
        backdrop-filter: blur(10px);
        padding: 1.5rem 0;
        border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        z-index: 999;
    }

    nav.active {
        display: block;
    }

    nav ul {
        flex-direction: column;
        align-items: center;
        gap: 1.5rem;
        margin: 0;
    }

    .section {
        padding: 2rem 1rem;
    }
}