:root {
    --bg-color: #f5f5f5;
    --container-bg: #ffffff;
    --text-color: #333;
    --text-secondary: #666;
    --text-muted: #555;
    --border-color: #e0e0e0;
    --shadow: rgba(0, 0, 0, 0.1);
    --header-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-color: #667eea;
    --notice-bg: #fff3cd;
    --notice-border: #ffc107;
    --notice-text: #856404;
    --info-bg: #e7f3ff;
    --info-border: #2196F3;
    --info-text: #1976D2;
    --contact-bg: #f9f9f9;
    --footer-bg: #f5f5f5;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --container-bg: #2d2d2d;
    --text-color: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-muted: #c0c0c0;
    --border-color: #404040;
    --shadow: rgba(0, 0, 0, 0.3);
    --header-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-color: #7c8ef5;
    --notice-bg: #3d2e00;
    --notice-border: #ffc107;
    --notice-text: #ffd54f;
    --info-bg: #1a2a3a;
    --info-border: #2196F3;
    --info-text: #64b5f6;
    --contact-bg: #252525;
    --footer-bg: #1a1a1a;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    padding: 20px;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background-color: var(--container-bg);
    box-shadow: 0 2px 10px var(--shadow);
    border-radius: 8px;
    overflow: hidden;
    position: relative;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.controls {
    position: absolute;
    top: 20px;
    right: 20px;
    display: flex;
    gap: 12px;
    z-index: 100;
    align-items: center;
}

.language-switcher {
    display: flex;
    gap: 8px;
    background-color: var(--container-bg);
    padding: 4px;
    border-radius: 8px;
    box-shadow: 0 2px 8px var(--shadow);
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.dark-mode-toggle {
    width: 44px;
    height: 44px;
    border: none;
    background-color: var(--container-bg);
    color: var(--primary-color);
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 8px var(--shadow);
    transition: all 0.3s ease;
    position: relative;
}

.dark-mode-toggle:hover {
    transform: scale(1.05);
    box-shadow: 0 4px 12px var(--shadow);
}

.dark-mode-toggle svg {
    position: absolute;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.dark-mode-toggle .icon-sun {
    opacity: 1;
    transform: rotate(0deg);
}

.dark-mode-toggle .icon-moon {
    opacity: 0;
    transform: rotate(90deg);
}

[data-theme="dark"] .dark-mode-toggle .icon-sun {
    opacity: 0;
    transform: rotate(90deg);
}

[data-theme="dark"] .dark-mode-toggle .icon-moon {
    opacity: 1;
    transform: rotate(0deg);
}

.lang-btn {
    padding: 8px 16px;
    border: none;
    background-color: transparent;
    color: var(--primary-color);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    border-radius: 6px;
    transition: all 0.2s ease;
    font-family: inherit;
}

.lang-btn:hover {
    background-color: rgba(102, 126, 234, 0.1);
}

.lang-btn.active {
    background-color: var(--primary-color);
    color: white;
}

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 70px 30px 40px 30px;
    text-align: center;
}

.header h1 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.3;
}

.meta-info {
    display: flex;
    justify-content: center;
    gap: 30px;
    flex-wrap: wrap;
    margin-top: 20px;
    font-size: 14px;
    opacity: 0.95;
}

.meta-info p {
    margin: 0;
}

.content {
    padding: 40px 30px;
}

.intro {
    margin-bottom: 40px;
    padding-bottom: 30px;
    border-bottom: 2px solid var(--border-color);
}

.intro p {
    margin-bottom: 15px;
    font-size: 16px;
}

.important-notice {
    background-color: var(--notice-bg);
    border-left: 4px solid var(--notice-border);
    padding: 15px 20px;
    margin: 20px 0;
    border-radius: 4px;
    color: var(--notice-text);
    transition: background-color 0.3s ease, color 0.3s ease;
}

section {
    margin-bottom: 40px;
    scroll-margin-top: 20px;
}

section h2 {
    color: var(--primary-color);
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border-color);
}

section h3 {
    color: var(--text-muted);
    font-size: 20px;
    font-weight: 600;
    margin-top: 25px;
    margin-bottom: 15px;
}

section p {
    margin-bottom: 15px;
    font-size: 16px;
    line-height: 1.7;
}

section ul {
    margin-left: 30px;
    margin-bottom: 20px;
    list-style-type: disc;
}

section li {
    margin-bottom: 10px;
    font-size: 16px;
    line-height: 1.6;
}

.notice-box {
    background-color: var(--info-bg);
    border-left: 4px solid var(--info-border);
    padding: 20px;
    margin: 25px 0;
    border-radius: 4px;
    transition: background-color 0.3s ease;
}

.notice-box strong {
    color: var(--info-text);
    display: block;
    margin-bottom: 10px;
    font-size: 17px;
}

.notice-box p {
    margin: 0;
    color: var(--text-muted);
}

.note {
    font-style: italic;
    color: var(--text-secondary);
    font-size: 14px;
}

.contact-info {
    background-color: var(--contact-bg);
    padding: 25px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.contact-info p {
    margin-bottom: 12px;
}

.contact-info a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.contact-info a:hover {
    text-decoration: underline;
}

.footer {
    background-color: var(--footer-bg);
    padding: 20px 30px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 14px;
    border-top: 1px solid var(--border-color);
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    .controls {
        top: 10px;
        right: 10px;
        gap: 8px;
    }

    .language-switcher {
        padding: 3px;
    }

    .dark-mode-toggle {
        width: 40px;
        height: 40px;
    }

    .lang-btn {
        padding: 6px 12px;
        font-size: 13px;
    }

    .header {
        padding: 60px 20px 30px 20px;
    }

    .header h1 {
        font-size: 22px;
    }

    .meta-info {
        flex-direction: column;
        gap: 10px;
        font-size: 13px;
    }

    .content {
        padding: 30px 20px;
    }

    section h2 {
        font-size: 20px;
    }

    section h3 {
        font-size: 18px;
    }

    section p,
    section li {
        font-size: 15px;
    }

    section ul {
        margin-left: 20px;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 18px;
    }

    .content {
        padding: 20px 15px;
    }

    section h2 {
        font-size: 18px;
    }

    section h3 {
        font-size: 16px;
    }
}

/* Print Styles */
@media print {
    body {
        background-color: white;
        padding: 0;
    }

    .container {
        box-shadow: none;
        border-radius: 0;
    }

    .header {
        background: #667eea;
        -webkit-print-color-adjust: exact;
        print-color-adjust: exact;
    }

    .footer {
        display: none;
    }
}