/* ========================================
   Koyso - 主题变量与全局样式
   ======================================== */

:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --accent-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --cta-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #4facfe 100%);
    --primary-start: #667eea;
    --primary-end: #764ba2;
    --accent-start: #4facfe;
    --accent-end: #00f2fe;
    --bg-dark: #0c0c1d;
    --bg-dark-alt: #1a1a2e;
    --bg-light: #f8f9fa;
    --card-bg: #ffffff;
    --card-bg-alt: #f7fafc;
    --text-dark: #2d3748;
    --text-body: #718096;
    --text-light: #a0aec0;
    --text-white: #ffffff;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 30px rgba(102, 126, 234, 0.3);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --header-height: 72px;
}

/* ========================================
   Reset & Base
   ======================================== */

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    color: var(--text-dark);
    background-color: var(--bg-light);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

img {
    max-width: 100%;
    height: auto;
}

ul, ol {
    list-style: none;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ========================================
   按钮通用样式
   ======================================== */

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    border: none;
    transition: var(--transition);
    font-family: var(--font-family);
    white-space: nowrap;
}

.btn i {
    font-size: 0.9em;
}

.btn-primary {
    background: var(--primary-gradient);
    color: var(--text-white);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.5);
}

.btn-outline {
    background: transparent;
    color: var(--text-white);
    border: 2px solid rgba(255, 255, 255, 0.4);
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.8);
    transform: translateY(-2px);
}

.btn-lg {
    padding: 14px 32px;
    font-size: 1.05rem;
}

.btn-sm {
    padding: 8px 20px;
    font-size: 0.9rem;
    background: var(--primary-gradient);
    color: var(--text-white);
    border-radius: 50px;
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.3);
}

.btn-sm:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.5);
}

.btn-block {
    display: flex;
    justify-content: center;
    width: 100%;
}

.btn-nav {
    background: var(--primary-gradient);
    color: var(--text-white);
    padding: 10px 24px;
    font-size: 0.9rem;
    box-shadow: 0 2px 10px rgba(102, 126, 234, 0.3);
}

.btn-nav:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.5);
}

/* ========================================
   Header 头部导航
   ======================================== */

.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--header-height);
    z-index: 1000;
    transition: var(--transition);
    background: transparent;
}

.header.scrolled {
    background: rgba(12, 12, 29, 0.95);
    backdrop-filter: blur(20px);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    z-index: 1001;
}

.logo-icon {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-white);
    letter-spacing: -0.5px;
}

.nav {
    display: flex;
    align-items: center;
    gap: 4px;
}

.nav-link {
    color: rgba(255, 255, 255, 0.8);
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 400;
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav-link i {
    font-size: 0.85rem;
}

.nav-link:hover,
.nav-link.active {
    color: var(--text-white);
    background: rgba(255, 255, 255, 0.1);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 28px;
    height: 28px;
    background: none;
    border: none;
    cursor: pointer;
    z-index: 1001;
    padding: 0;
}

.menu-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-white);
    border-radius: 2px;
    transition: var(--transition);
}

.menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* ========================================
   Hero 首屏区域
   ======================================== */

.hero {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    padding: calc(var(--header-height) + 48px) 0 56px;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: var(--bg-dark);
    z-index: -2;
}

.hero-bg::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 20% 50%, rgba(102, 126, 234, 0.3) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 20%, rgba(118, 75, 162, 0.3) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 80%, rgba(79, 172, 254, 0.15) 0%, transparent 50%);
    animation: heroPulse 8s ease-in-out infinite alternate;
}

.hero-bg::after {
    content: '';
    position: absolute;
    inset: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23667eea' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.5;
}

@keyframes heroPulse {
    0% { opacity: 1; transform: scale(1); }
    100% { opacity: 0.8; transform: scale(1.05); }
}

.hero .container {
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-content {
    margin-bottom: 36px;
}

.hero-title {
    font-size: clamp(2.2rem, 5vw, 3.2rem);
    font-weight: 900;
    color: var(--text-white);
    margin-bottom: 14px;
    line-height: 1.2;
    letter-spacing: -1px;
    background: linear-gradient(135deg, #fff 0%, #e0e7ff 50%, #c7d2fe 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(0.95rem, 2vw, 1.1rem);
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.7;
    margin-bottom: 28px;
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    max-width: 700px;
    margin: 0 auto;
    padding: 24px 32px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(10px);
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 2px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.5);
}

/* ========================================
   通用 Section 样式
   ======================================== */

.section {
    padding: 100px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 16px;
    letter-spacing: -0.5px;
}

.section-desc {
    font-size: 1.1rem;
    color: var(--text-body);
    max-width: 600px;
    margin: 0 auto;
}

/* ========================================
   Features 特色卡片
   ======================================== */

.features-section {
    background: var(--card-bg);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.feature-card {
    padding: 36px 28px;
    background: var(--card-bg-alt);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    transition: var(--transition);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-start);
}

.feature-icon {
    width: 64px;
    height: 64px;
    border-radius: var(--radius-md);
    background: var(--primary-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 1.5rem;
    color: var(--text-white);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.feature-card h3 {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 10px;
}

.feature-card p {
    font-size: 0.9rem;
    color: var(--text-body);
    line-height: 1.7;
}

/* ========================================
   Resources 资源类型
   ======================================== */

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

.resources-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.resource-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 32px 24px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.resource-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-start);
}

.resource-icon {
    width: 72px;
    height: 72px;
    border-radius: 50%;
    background: var(--primary-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    color: var(--text-white);
    margin-bottom: 20px;
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.3);
}

.resource-card h3 {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 16px;
}

.resource-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    justify-content: center;
    margin-bottom: 20px;
}

.resource-tags span {
    padding: 4px 12px;
    background: rgba(102, 126, 234, 0.08);
    color: var(--primary-start);
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* ========================================
   Functions 功能体系
   ======================================== */

.functions-section {
    background: var(--bg-dark);
    position: relative;
    overflow: hidden;
}

.functions-section::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 30% 30%, rgba(102, 126, 234, 0.15) 0%, transparent 60%),
        radial-gradient(ellipse at 70% 70%, rgba(118, 75, 162, 0.15) 0%, transparent 60%);
}

.functions-section .section-title {
    color: var(--text-white);
}

.functions-section .section-desc {
    color: rgba(255, 255, 255, 0.6);
}

.functions-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    position: relative;
    z-index: 1;
}

.function-card {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    padding: 28px 20px;
    text-align: center;
    transition: var(--transition);
    backdrop-filter: blur(5px);
}

.function-card:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(102, 126, 234, 0.5);
    transform: translateY(-4px);
    box-shadow: 0 8px 30px rgba(102, 126, 234, 0.2);
}

.function-icon {
    width: 52px;
    height: 52px;
    border-radius: var(--radius-sm);
    background: var(--primary-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    color: var(--text-white);
    margin: 0 auto 16px;
}

.function-card h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-white);
    margin-bottom: 8px;
}

.function-card p {
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.5);
    line-height: 1.7;
}

/* ========================================
   Membership 会员特权
   ======================================== */

.membership-section {
    background: var(--card-bg);
}

.membership-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
    max-width: 800px;
    margin: 0 auto;
}

.membership-card {
    background: var(--card-bg-alt);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    border: 2px solid var(--border-color);
    transition: var(--transition);
    position: relative;
    text-align: center;
}

.membership-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.membership-card.recommended {
    border-color: var(--primary-start);
    background: var(--card-bg);
    box-shadow: var(--shadow-glow);
}

.membership-badge {
    display: inline-block;
    padding: 4px 16px;
    background: var(--border-color);
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-body);
    margin-bottom: 16px;
}

.membership-card.recommended .membership-badge {
    background: var(--primary-gradient);
    color: var(--text-white);
}

.membership-card h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 12px;
}

.membership-price {
    margin-bottom: 28px;
}

.membership-price .price {
    font-size: 2.5rem;
    font-weight: 900;
    color: var(--text-dark);
}

.membership-card.recommended .membership-price .price {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.membership-price .period {
    font-size: 0.9rem;
    color: var(--text-body);
}

.membership-features {
    text-align: left;
    margin-bottom: 28px;
}

.membership-features li {
    padding: 8px 0;
    font-size: 0.95rem;
    color: var(--text-dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.membership-features li i {
    font-size: 0.85rem;
    color: #48bb78;
    width: 18px;
    text-align: center;
}

.membership-features li.disabled {
    color: var(--text-light);
}

.membership-features li.disabled i {
    color: var(--text-light);
}

/* ========================================
   Security 安全保障
   ======================================== */

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

.security-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.security-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 36px 24px;
    text-align: center;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.security-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-start);
}

.security-icon {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin: 0 auto 16px;
    color: var(--primary-start);
}

.security-card h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 8px;
}

.security-card p {
    font-size: 0.9rem;
    color: var(--text-body);
}

/* ========================================
   News 最新资讯
   ======================================== */

.news-section {
    background: var(--card-bg);
}

.news-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.news-card {
    background: var(--card-bg-alt);
    border-radius: var(--radius-lg);
    padding: 28px 24px;
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.news-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-start);
}

.news-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 14px;
}

.news-date {
    font-size: 0.8rem;
    color: var(--text-light);
    display: flex;
    align-items: center;
    gap: 6px;
}

.news-tag {
    font-size: 0.75rem;
    padding: 2px 10px;
    background: rgba(102, 126, 234, 0.1);
    color: var(--primary-start);
    border-radius: 50px;
    font-weight: 500;
}

.news-card h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 10px;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-card p {
    font-size: 0.9rem;
    color: var(--text-body);
    margin-bottom: 16px;
    line-height: 1.7;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-link {
    font-size: 0.9rem;
    color: var(--primary-start);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.news-link:hover {
    color: var(--primary-end);
    gap: 10px;
}

/* ========================================
   FAQ 常见问题
   ======================================== */

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

.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 12px;
    overflow: hidden;
    transition: var(--transition);
}

.faq-item:hover {
    border-color: var(--primary-start);
}

.faq-item.active {
    border-color: var(--primary-start);
    box-shadow: var(--shadow-md);
}

.faq-question {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-dark);
    font-size: 1rem;
    user-select: none;
}

.faq-question i {
    font-size: 0.85rem;
    color: var(--text-body);
    transition: var(--transition);
    flex-shrink: 0;
    margin-left: 16px;
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
    color: var(--primary-start);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s cubic-bezier(0.4, 0, 0.2, 1), padding 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    padding: 0 24px;
}

.faq-item.active .faq-answer {
    max-height: 300px;
    padding: 0 24px 20px;
}

.faq-answer p {
    font-size: 0.95rem;
    color: var(--text-body);
    line-height: 1.8;
}

/* ========================================
   CTA 行动横幅
   ======================================== */

.cta-section {
    background: var(--bg-dark);
    padding: 80px 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.cta-section::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 50% 50%, rgba(102, 126, 234, 0.2) 0%, transparent 70%);
}

.cta-section .container {
    position: relative;
    z-index: 1;
}

.cta-section h2 {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 16px;
}

.cta-section p {
    font-size: 1.1rem;
    color: rgba(255, 255, 255, 0.6);
    margin-bottom: 32px;
}

/* ========================================
   Footer 底部
   ======================================== */

.footer {
    background: var(--bg-dark-alt);
    padding: 60px 0 0;
    color: rgba(255, 255, 255, 0.6);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand p {
    font-size: 0.9rem;
    line-height: 1.7;
    margin-top: 16px;
    color: rgba(255, 255, 255, 0.5);
}

.footer-social {
    display: flex;
    gap: 12px;
    margin-top: 20px;
}

.footer-social a {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.08);
    display: flex;
    align-items: center;
    justify-content: center;
    color: rgba(255, 255, 255, 0.6);
    font-size: 1rem;
    transition: var(--transition);
}

.footer-social a:hover {
    background: var(--primary-gradient);
    color: var(--text-white);
    transform: translateY(-2px);
}

.footer-links h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-white);
    margin-bottom: 20px;
}

.footer-links a {
    display: block;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.5);
    padding: 6px 0;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--text-white);
    padding-left: 4px;
}

.footer-bottom {
    text-align: center;
    padding: 24px 0;
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.3);
}

/* ========================================
   返回顶部按钮
   ======================================== */

.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary-gradient);
    color: var(--text-white);
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
    transition: var(--transition);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.5);
}

/* ========================================
   按钮点击反馈
   ======================================== */

.btn:active {
    transform: scale(0.97);
}

.btn-primary:active,
.btn-nav:active,
.btn-sm:active {
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.3);
}

/* ========================================
   响应式布局
   ======================================== */

@media (max-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

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

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

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

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

@media (max-width: 768px) {
    :root {
        --header-height: 64px;
    }

    .nav {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background: rgba(12, 12, 29, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        align-items: stretch;
        padding: 90px 24px 40px;
        gap: 4px;
        transition: right 0.3s ease;
        z-index: 1000;
    }

    .nav.active {
        right: 0;
    }

    .nav-link {
        padding: 14px 16px;
        font-size: 1rem;
        border-radius: var(--radius-sm);
    }

    .btn-nav {
        display: none;
    }

    .menu-toggle {
        display: flex;
    }

    .hero {
        padding: calc(var(--header-height) + 32px) 0 40px;
    }

    .hero-stats {
        grid-template-columns: repeat(2, 1fr);
        padding: 18px 16px;
        gap: 12px;
    }

    .stat-number {
        font-size: 1.1rem;
    }

    .section {
        padding: 70px 0;
    }

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

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

    .functions-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }

    .membership-grid {
        grid-template-columns: 1fr;
        max-width: 400px;
    }

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

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

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .cta-section {
        padding: 60px 0;
    }
}

@media (max-width: 480px) {
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .hero-buttons .btn {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }

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

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

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

/* ========================================
   子页面通用样式
   ======================================== */

.page-hero {
    background: var(--bg-dark);
    position: relative;
    overflow: hidden;
    padding: calc(var(--header-height) + 48px) 0 48px;
    text-align: center;
}

.page-hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 30% 50%, rgba(102, 126, 234, 0.25) 0%, transparent 55%),
        radial-gradient(ellipse at 70% 30%, rgba(118, 75, 162, 0.2) 0%, transparent 55%);
    pointer-events: none;
}

.page-hero .container {
    position: relative;
    z-index: 1;
}

.page-hero h1 {
    font-size: clamp(1.8rem, 4vw, 2.4rem);
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 10px;
    background: linear-gradient(135deg, #fff 0%, #e0e7ff 50%, #c7d2fe 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-hero p {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.6);
    max-width: 520px;
    margin: 0 auto;
}

.page-breadcrumb {
    margin-bottom: 16px;
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.4);
}

.page-breadcrumb a {
    color: rgba(255, 255, 255, 0.6);
}

.page-breadcrumb a:hover {
    color: var(--text-white);
}

.page-breadcrumb span {
    margin: 0 8px;
}

.page-content {
    padding: 64px 0 80px;
    background: var(--bg-light);
}

.page-content .container {
    max-width: 880px;
}

.content-block {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 40px;
    margin-bottom: 24px;
}

.content-block h2 {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.content-block h2 i {
    font-size: 1.1rem;
    color: var(--primary-start);
}

.content-block h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-dark);
    margin: 20px 0 8px;
}

.content-block p {
    font-size: 0.95rem;
    color: var(--text-body);
    line-height: 1.8;
    margin-bottom: 12px;
}

.content-block p:last-child {
    margin-bottom: 0;
}

.content-block ul,
.content-block ol {
    padding-left: 20px;
    margin-bottom: 12px;
}

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

.content-block ul li {
    position: relative;
    padding: 6px 0 6px 24px;
    font-size: 0.95rem;
    color: var(--text-body);
    line-height: 1.7;
}

.content-block ul li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 14px;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--primary-gradient);
}

.content-block ol li {
    padding: 6px 0;
    font-size: 0.95rem;
    color: var(--text-body);
    line-height: 1.7;
}

.content-block .highlight-box {
    background: rgba(102, 126, 234, 0.06);
    border-left: 4px solid var(--primary-start);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    padding: 16px 20px;
    margin: 16px 0;
}

.content-block .highlight-box p {
    margin-bottom: 0;
    color: var(--text-dark);
    font-weight: 500;
}

.page-updated {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-light);
    margin-top: 32px;
}

@media (max-width: 768px) {
    .content-block {
        padding: 24px 20px;
    }

    .page-content {
        padding: 40px 0 60px;
    }
}