:root {
    --primary-color: #f7931a;
    --secondary-color: #1a1a1a;
    --accent-color: #627eea;
    --background-color: #0a0e1a;
    --surface-color: #1a1f2e;
    --text-color: #ffffff;
    --text-color-light: #b0b8c9;
    --border-color: #2d3748;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --gradient-primary: linear-gradient(135deg, #f7931a 0%, #627eea 100%);
    --gradient-secondary: linear-gradient(135deg, #1a1f2e 0%, #2d3748 100%);

    --font-family-base: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', Meiryo, sans-serif;
    --font-family-heading: 'Georgia', 'Times New Roman', 'Hiragino Mincho ProN', serif;

    --header-height: 70px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: var(--font-family-base);
    line-height: 1.7;
    color: var(--text-color);
    background: var(--background-color);
    font-size: 16px;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-family-heading);
    color: var(--text-color);
    line-height: 1.3;
    margin-bottom: 1rem;
    font-weight: 600;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

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

img {
    max-width: 100%;
    height: auto;
    display: block;
    border-radius: 8px;
}

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

/* Header */
.header {
    background: rgba(26, 31, 46, 0.95);
    backdrop-filter: blur(15px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: var(--transition);
}

.header.scrolled {
    background: rgba(26, 31, 46, 0.98);
    box-shadow: 0 4px 20px var(--shadow-color);
}

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

.logo a {
    font-family: var(--font-family-heading);
    font-size: 1.5rem;
    font-weight: bold;
    background: var(--gradient-primary);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 1.5rem;
    align-items: center;
    flex-wrap: wrap;
    max-width: 900px;
    justify-content: center;
    margin: 0;
    padding: 0;
}

.nav-item a {
    font-weight: 500;
    color: var(--text-color-light);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    transition: var(--transition);
    font-size: 0.9rem;
    white-space: nowrap;
    position: relative;
}

.nav-item a:hover,
.nav-item a.active {
    color: var(--text-color);
    background: rgba(247, 147, 26, 0.1);
    transform: translateY(-1px);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 5px;
}

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

/* Hero Section */
.hero {
    position: relative;
    min-height: 80vh;
    display: flex;
    align-items: center;
    overflow: hidden;
    background: var(--gradient-secondary);
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 1;
    opacity: 0.6;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
    background: rgba(26, 31, 46, 0.8);
    border-radius: 20px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(247, 147, 26, 0.2);
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1.5rem;
    background: var(--gradient-primary);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-color-light);
    line-height: 1.8;
    margin-bottom: 2rem;
}

/* Main Content */
.page-wrapper {
    padding: 3rem 0;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
}

.article-content {
    background: var(--surface-color);
    padding: 3rem;
    border-radius: 15px;
    border: 1px solid var(--border-color);
    box-shadow: 0 10px 30px var(--shadow-color);
}

.two-column-layout {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
}

.sidebar {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: 15px;
    border: 1px solid var(--border-color);
    height: fit-content;
    position: sticky;
    top: calc(var(--header-height) + 2rem);
}

/* Feature Grid */
.feature-grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.feature-grid-item {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: 15px;
    border: 1px solid var(--border-color);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.feature-grid-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: var(--transition);
}

.feature-grid-item:hover::before {
    transform: scaleX(1);
}

.feature-grid-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 35px var(--shadow-color);
    border-color: var(--primary-color);
}

.feature-grid-item h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.feature-grid-item p {
    color: var(--text-color-light);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

/* Buttons */
.btn-read-more,
.cta-button {
    display: inline-block;
    background: var(--gradient-primary);
    color: var(--text-color);
    padding: 0.8rem 2rem;
    border-radius: 25px;
    font-weight: 600;
    text-align: center;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 0.95rem;
}

.btn-read-more:hover,
.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(247, 147, 26, 0.3);
    color: var(--text-color);
}

/* News List */
.news-list {
    list-style: none;
    margin: 2rem 0;
}

.news-item {
    background: var(--surface-color);
    margin-bottom: 1rem;
    padding: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid var(--primary-color);
    transition: var(--transition);
}

.news-item:hover {
    transform: translateX(5px);
    background: rgba(247, 147, 26, 0.05);
}

.news-item h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.news-item p {
    color: var(--text-color-light);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* Tables */
.crypto-table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    background: var(--surface-color);
    border-radius: 10px;
    overflow: hidden;
}

.crypto-table th,
.crypto-table td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.crypto-table th {
    background: var(--gradient-primary);
    color: var(--text-color);
    font-weight: 600;
}

.crypto-table tr:hover {
    background: rgba(247, 147, 26, 0.05);
}

/* Stats Cards */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.stat-card {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-3px);
    border-color: var(--primary-color);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: bold;
    background: var(--gradient-primary);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: block;
    margin-bottom: 0.5rem;
}

.stat-label {
    color: var(--text-color-light);
    font-size: 0.9rem;
}

/* Sidebar Components */
.sidebar-section {
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.sidebar-section:last-child {
    border-bottom: none;
}

.sidebar-section h3 {
    color: var(--primary-color);
    font-size: 1.2rem;
    margin-bottom: 1rem;
}

.related-links {
    list-style: none;
}

.related-links li {
    margin-bottom: 0.8rem;
}

.related-links a {
    color: var(--text-color-light);
    font-size: 0.9rem;
    transition: var(--transition);
    display: block;
    padding: 0.5rem 0;
    border-bottom: 1px solid transparent;
}

.related-links a:hover {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
    padding-left: 10px;
}

/* Footer */
.footer {
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 3rem 0 2rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.5rem;
}

.footer-links a {
    color: var(--text-color-light);
    font-size: 0.9rem;
    transition: var(--transition);
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-color-light);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: -100%;
        width: 100%;
        height: calc(100vh - var(--header-height));
        background: var(--surface-color);
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        padding-top: 2rem;
        transition: var(--transition);
        backdrop-filter: blur(15px);
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-item {
        margin: 1rem 0;
        width: 100%;
        text-align: center;
    }

    .nav-item a {
        display: block;
        padding: 1rem;
        width: 100%;
        border-bottom: 1px solid var(--border-color);
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active .hamburger-inner {
        background-color: transparent;
    }

    .hamburger.active .hamburger-inner::before {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .hamburger.active .hamburger-inner::after {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .two-column-layout {
        grid-template-columns: 1fr;
        display: flex;
        flex-direction: column;
    }

    /* モバイルではサイドバーを本文より先に表示 */
    .sidebar {
        order: -1;
        position: relative;
        top: auto;
    }

    .article-content {
        order: 0;
        padding: 2rem;
    }

    .feature-grid-container {
        grid-template-columns: 1fr;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.25rem; }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .hero-content {
        padding: 1.5rem;
    }

    .article-content {
        padding: 1.5rem;
    }

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

    .crypto-table {
        font-size: 0.8rem;
    }

    .crypto-table th,
    .crypto-table td {
        padding: 0.5rem;
    }
}