/* ==================== */
/* CSS 变量定义         */
/* ==================== */
:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --dark-bg: #0f172a;
    --darker-bg: #020617;
    --text-light: #f1f5f9;
    --text-gray: #94a3b8;
    --card-bg: #1e293b;
    --gradient-start: #3b82f6;
    --gradient-end: #8b5cf6;
}

/* ==================== */
/* 基础重置和 body      */
/* ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', 'PingFang SC', sans-serif;
    background: var(--darker-bg);
    line-height: 1.6;
    overflow-x: hidden;
}

nav, section, footer, .pricing-hero, .pricing-section, .faq-section {
    color: var(--text-light);
}

/* ==================== */
/* 导航栏               */
/* ==================== */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(2, 6, 23, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 1000;
    padding: 0;
    border-bottom: 1px solid rgba(59, 130, 246, 0.1);
    transition: all 0.3s ease;
}

nav.scrolled {
    background: rgba(2, 6, 23, 0.95);
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.5);
    border-bottom-color: rgba(59, 130, 246, 0.2);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1.2rem 3rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-wrapper {
    display: flex;
    align-items: center;
    gap: 1rem;
    text-decoration: none;
    transition: transform 0.3s ease;
}

.logo-wrapper:hover {
    transform: translateY(-2px);
}

.logo-icon {
    width: 45px;
    height: 45px;
    position: relative;
}

.logo-icon svg {
    width: 100%;
    height: 100%;
    filter: drop-shadow(0 4px 12px rgba(59, 130, 246, 0.3));
}

.logo {
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
}

.logo-main {
    font-size: 1.4rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #60a5fa 0%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.2;
}

.logo-sub {
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-gray);
    letter-spacing: 0.05em;
}

.nav-links {
    display: flex;
    gap: 0;
    list-style: none;
    align-items: center;
}

.nav-links li {
    position: relative;
}

/* 导航链接 - 默认状态：明确透明背景，无背景变化 */
.nav-links a {
    color: var(--text-gray);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.8rem 1.5rem;
    display: block;
    position: relative;
    transition: color 0.3s ease;
    background-color: transparent;
    border-radius: 0;
}

/* 导航链接 - hover：只变色 + 下划线，不加背景 */
.nav-links a:hover {
    color: var(--text-light);
    background-color: transparent;
}

/* 下划线效果用 ::after，从中间展开 */
.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 6px;
    left: 50%;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--gradient-start), var(--gradient-end));
    transition: width 0.3s ease, left 0.3s ease;
    border-radius: 2px;
}

.nav-links a:hover::after {
    width: 50%;
    left: 25%;
}

/* 当前页面高亮 */
.nav-links a.active {
    color: var(--text-light);
}

.nav-links a.active::after {
    width: 50%;
    left: 25%;
}

/* 登录/注册按钮区域 */
.nav-cta {
    padding-left: 0.5rem;
}

/* 登录按钮 - 透明背景 + 边框 */
.nav-cta .btn-secondary {
    padding: 0.5rem 1.2rem;
    font-size: 0.9rem;
    background-color: transparent;
    color: var(--text-light);
    border: 1.5px solid var(--accent-color);
    border-radius: 50px;
    transition: all 0.3s ease;
}

.nav-cta .btn-secondary:hover {
    border-color: var(--text-light);
    color: var(--text-light);
    background-color: transparent;
    transform: none;
}

/* 注册按钮 - 渐变背景 */
.nav-cta .btn-primary {
    padding: 0.5rem 1.2rem;
    font-size: 0.9rem;
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    color: white;
    border: none;
    border-radius: 50px;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
    transition: box-shadow 0.3s ease;
    position: relative;
    overflow: hidden;
}

.nav-cta .btn-primary:hover {
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.5);
    transform: none;
}

/* 按钮扫光效果 */
.nav-cta .btn-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.5s;
}

.nav-cta .btn-primary:hover::before {
    left: 100%;
}

/* 导航栏用户下拉菜单 */
.nav-user {
    position: relative;
    display: flex;
    align-items: center;
    padding: 0.5rem 0 0.5rem 1.2rem;
}

.nav-username {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 16px;
    background: rgba(96, 165, 250, 0.1);
    border: 1px solid rgba(96, 165, 250, 0.25);
    border-radius: 20px;
    color: #60a5fa;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

.nav-username::after {
    content: '';
    display: inline-block;
    width: 0;
    height: 0;
    border-left: 4px solid transparent;
    border-right: 4px solid transparent;
    border-top: 4px solid #60a5fa;
    margin-left: 2px;
    transition: transform 0.2s;
}

.nav-user:hover .nav-username {
    background: rgba(96, 165, 250, 0.18);
    border-color: rgba(96, 165, 250, 0.4);
    color: #93bbfc;
}

.nav-user:hover .nav-username::after {
    transform: rotate(180deg);
    border-top-color: #93bbfc;
}

.nav-dropdown {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    min-width: 140px;
    background: #1e293b;
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 10px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
    padding: 6px 0;
    z-index: 1000;
    animation: dropFadeIn 0.15s ease;
}

@keyframes dropFadeIn {
    from { opacity: 0; transform: translateY(-6px); }
    to { opacity: 1; transform: translateY(0); }
}

.nav-user:hover .nav-dropdown {
    display: block;
}

.nav-dropdown a {
    display: block;
    padding: 10px 18px;
    color: var(--text-gray);
    font-size: 0.85rem;
    text-decoration: none;
    transition: all 0.15s;
}

.nav-dropdown a:hover {
    color: var(--text-light);
    background: rgba(255, 255, 255, 0.05);
}

/* ==================== */
/* 按钮样式             */
/* ==================== */
.btn {
    padding: 1rem 2.5rem;
    border: none;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    color: white;
    box-shadow: 0 10px 30px rgba(59, 130, 246, 0.4);
    position: relative;
    overflow: hidden;
}

.btn-primary::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.5s;
}

.btn-primary:hover::before {
    left: 100%;
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 40px rgba(59, 130, 246, 0.5);
}

.btn-secondary {
    background: transparent;
    color: var(--text-light);
    border: 2px solid var(--accent-color);
}

.btn-secondary:hover {
    background: var(--accent-color);
    transform: translateY(-3px);
}

/* ==================== */
/* 通用 section 标题    */
/* ==================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
}

.section-title {
    text-align: center;
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    text-align: center;
    color: var(--text-gray);
    font-size: 1.2rem;
    margin-bottom: 4rem;
}

/* ==================== */
/* 页脚样式             */
/* ==================== */
footer {
    background: var(--darker-bg);
    padding: 3rem 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    text-align: center;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--text-gray);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.copyright {
    color: var(--text-gray);
    font-size: 0.9rem;
}

/* ==================== */
/* 响应式基础           */
/* ==================== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .section-title {
        font-size: 2rem;
    }
}