/* 基础变量 (Nordic Minimalist) */
:root {
    --bg-color: #F9FAFB;
    --bg-alt: #FFFFFF;
    --text-color: #111827;
    --text-muted: #4B5563;
    --primary-color: #059669;
    --primary-hover: #047857;
    --card-bg: #FFFFFF;
    --border-color: #E5E7EB;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --spring: cubic-bezier(0.175, 0.885, 0.32, 1.275);
    --nav-height: 72px;
}

[data-theme="dark"] {
    --bg-color: #111827;
    --bg-alt: #1F2937;
    --text-color: #F9FAFB;
    --text-muted: #9CA3AF;
    --primary-color: #10B981;
    --primary-hover: #34D399;
    --card-bg: #1F2937;
    --border-color: #374151;
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
}

/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color var(--transition), color var(--transition);
}

a {
    text-decoration: none;
    color: inherit;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 96px 0;
}

.bg-alt {
    background-color: var(--bg-alt);
}

.section-title {
    text-align: center;
    font-size: 2.25rem;
    margin-bottom: 16px;
    font-weight: 700;
    color: var(--text-color);
    letter-spacing: -0.02em;
}

.section-desc {
    text-align: center;
    color: var(--text-muted);
    margin-bottom: 56px;
    font-size: 1.125rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* 网格系统 */
.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

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

/* 卡片 */
.card {
    background-color: var(--card-bg);
    border-radius: 16px;
    padding: 32px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: transform var(--transition), box-shadow var(--transition);
}

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

/* 按钮 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: transform 0.2s var(--spring), background-color 0.2s, color 0.2s, border-color 0.2s;
    border: 1px solid transparent;
    min-height: 48px;
}

.btn:active {
    transform: scale(0.96);
}

.btn-primary {
    background-color: var(--text-color);
    color: var(--bg-color);
}

.btn-primary:hover {
    background-color: var(--text-muted);
}

.btn-outline {
    background-color: transparent;
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-outline:hover {
    border-color: var(--text-muted);
}

.btn-block {
    width: 100%;
}

/* 导航栏 */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--nav-height);
    background-color: rgba(var(--bg-color), 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
}

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

.nav-left, .nav-right {
    display: flex;
    align-items: center;
    gap: 24px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-color);
    letter-spacing: -0.02em;
}

.uptime-pill {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 4px 12px;
    border-radius: 99px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

.status-dot {
    width: 8px;
    height: 8px;
    background-color: var(--primary-color);
    border-radius: 50%;
}

.nav-links {
    display: flex;
    gap: 24px;
}

.nav-links a {
    font-size: 0.9375rem;
    color: var(--text-muted);
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover, .nav-links a.active {
    color: var(--text-color);
}

.nav-highlight {
    color: var(--primary-color) !important;
}

.theme-toggle {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-muted);
    transition: var(--transition);
}

.theme-toggle:hover {
    color: var(--text-color);
    border-color: var(--text-muted);
}

html[data-theme="dark"] .sun-icon { display: block; }
html[data-theme="dark"] .moon-icon { display: none; }
html[data-theme="light"] .sun-icon { display: none; }
html[data-theme="light"] .moon-icon { display: block; }

.nav-login {
    min-height: 40px;
    padding: 8px 16px;
    font-size: 0.9375rem;
}

/* 英雄区 */
.hero {
    padding-top: calc(var(--nav-height) + 80px);
    padding-bottom: 80px;
    text-align: center;
}

.hero-content {
    max-width: 800px;
}

.headline {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 24px;
    line-height: 1.1;
    color: var(--text-color);
    letter-spacing: -0.03em;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-bottom: 64px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* 容量计算器滑块 */
.calculator-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 40px;
    box-shadow: var(--shadow-md);
    max-width: 640px;
    margin: 0 auto;
    text-align: left;
}

.calc-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 32px;
}

.calc-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
}

.calc-badge {
    background-color: rgba(5, 150, 105, 0.1);
    color: var(--primary-color);
    padding: 4px 12px;
    border-radius: 99px;
    font-size: 0.875rem;
    font-weight: 600;
}

.calc-slider-wrapper {
    margin-bottom: 32px;
}

.range-slider {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    background: var(--border-color);
    border-radius: 3px;
    outline: none;
    margin-bottom: 12px;
}

.range-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--text-color);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: transform 0.1s;
}

.range-slider::-webkit-slider-thumb:active {
    transform: scale(1.1);
}

.slider-labels {
    display: flex;
    justify-content: space-between;
    color: var(--text-muted);
    font-size: 0.875rem;
    font-weight: 500;
}

.calc-results {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin-bottom: 32px;
    background-color: var(--bg-color);
    padding: 24px;
    border-radius: 12px;
}

.result-item {
    display: flex;
    flex-direction: column;
}

.res-label {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 4px;
}

.res-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
}

.res-value span {
    font-weight: 800;
}

/* 特性与支持 */
.feature-card, .ai-card {
    text-align: left;
}

.card-icon {
    color: var(--text-color);
    margin-bottom: 24px;
}

.feature-card h3, .ai-card h3 {
    font-size: 1.25rem;
    margin-bottom: 12px;
    font-weight: 600;
}

.feature-card p, .ai-card p {
    color: var(--text-muted);
    font-size: 1rem;
}

/* 流媒体 */
.media-card {
    text-align: center;
    padding: 24px;
}
.media-card h3 {
    font-size: 1.25rem;
    margin-bottom: 4px;
    font-weight: 700;
}
.card-meta {
    font-size: 0.875rem;
    color: var(--primary-color);
    font-weight: 500;
}

/* 教程选项卡 */
.tutorial-wrapper {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.tabs {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-color);
}

.tab-btn {
    flex: 1;
    background: transparent;
    border: none;
    padding: 16px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-muted);
    cursor: pointer;
    transition: color 0.2s, background-color 0.2s;
    border-bottom: 2px solid transparent;
}

.tab-btn:hover {
    color: var(--text-color);
    background-color: rgba(0,0,0,0.02);
}

.tab-btn.active {
    color: var(--text-color);
    border-bottom-color: var(--text-color);
    background-color: var(--card-bg);
}

.tab-content {
    display: none;
    padding: 40px;
}
.tab-content.active {
    display: block;
    animation: fadeIn 0.4s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.step-guide {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.step {
    position: relative;
    padding-left: 48px;
}

.step-num {
    position: absolute;
    left: 0;
    top: 0;
    width: 32px;
    height: 32px;
    background-color: var(--text-color);
    color: var(--bg-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.9rem;
}

.step h4 {
    font-size: 1.125rem;
    margin-bottom: 8px;
}

.step p {
    color: var(--text-muted);
    margin-bottom: 16px;
}

.action-group {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

/* 价格卡片 */
.pricing-card {
    display: flex;
    flex-direction: column;
    position: relative;
}

.pricing-card.featured {
    border: 2px solid var(--text-color);
    transform: scale(1.02);
}

.pricing-card.featured:hover {
    transform: scale(1.02) translateY(-4px);
}

.plan-name {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-muted);
}
.pricing-card.featured .plan-name {
    color: var(--text-color);
}

.badge {
    position: absolute;
    top: -14px;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--text-color);
    color: var(--bg-color);
    padding: 4px 16px;
    border-radius: 99px;
    font-size: 0.875rem;
    font-weight: 600;
}

.price {
    font-size: 3rem;
    font-weight: 800;
    margin: 24px 0;
    color: var(--text-color);
    letter-spacing: -0.05em;
}

.period {
    font-size: 1rem;
    color: var(--text-muted);
    font-weight: 500;
    letter-spacing: normal;
}

.pricing-features {
    list-style: none;
    margin-bottom: 40px;
    flex-grow: 1;
}

.pricing-features li {
    padding: 12px 0;
    color: var(--text-color);
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 12px;
    border-bottom: 1px solid var(--border-color);
}
.pricing-features li:last-child {
    border-bottom: none;
}

.check {
    width: 20px;
    height: 20px;
    stroke: var(--primary-color);
    fill: none;
    stroke-width: 3;
    stroke-linecap: round;
    stroke-linejoin: round;
}

/* 评论 */
.review-card {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}
.review-text {
    font-size: 1rem;
    color: var(--text-color);
    margin-bottom: 24px;
    line-height: 1.7;
}
.reviewer {
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.9rem;
}

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

.faq-item {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    margin-bottom: 16px;
    overflow: hidden;
}

.faq-item summary {
    padding: 24px;
    font-weight: 600;
    cursor: pointer;
    list-style: none;
    position: relative;
    user-select: none;
    font-size: 1.125rem;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: '+';
    position: absolute;
    right: 24px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.5rem;
    color: var(--text-muted);
    transition: transform 0.3s;
}

.faq-item[open] summary::after {
    transform: translateY(-50%) rotate(45deg);
}

.faq-content {
    padding: 0 24px 24px;
    color: var(--text-muted);
    line-height: 1.7;
}

/* Footer */
.footer {
    background-color: var(--bg-alt);
    padding: 64px 0 40px;
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-links {
    margin-bottom: 32px;
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--text-muted);
    font-weight: 500;
    transition: color 0.2s;
}

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

.footer-copyright {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* 模态框 */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.4);
    backdrop-filter: blur(4px);
    align-items: center;
    justify-content: center;
}
.modal.show {
    display: flex;
}
.modal-content {
    background-color: var(--card-bg);
    padding: 32px;
    border-radius: 20px;
    text-align: center;
    position: relative;
    box-shadow: 0 20px 25px -5px rgba(0,0,0,0.1);
    border: 1px solid var(--border-color);
    max-width: 90%;
    width: 320px;
    animation: fadeIn 0.3s ease;
}
.close-btn {
    position: absolute;
    top: 16px;
    right: 20px;
    font-size: 24px;
    font-weight: bold;
    color: var(--text-muted);
    cursor: pointer;
}
.close-btn:hover {
    color: var(--text-color);
}
.modal-header {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 24px;
}
.qr-placeholder {
    color: var(--text-muted);
    margin-bottom: 16px;
}

/* 响应式 */
@media (max-width: 992px) {
    .nav-links {
        display: none; /* 移动端精简导航 */
    }
    .grid-3, .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
    .pricing-card.featured {
        transform: scale(1);
    }
    .pricing-card.featured:hover {
        transform: scale(1) translateY(-4px);
    }
    .headline {
        font-size: 2.5rem;
    }
    .nav-left .uptime-pill {
        display: none;
    }
}

@media (max-width: 640px) {
    .grid-3, .grid-4 {
        grid-template-columns: 1fr;
    }
    .calc-results {
        grid-template-columns: 1fr;
        gap: 16px;
    }
    .action-group .btn {
        width: 100%;
    }
    .section {
        padding: 64px 0;
    }
}