/* ============================================================
   Flat SaaS Design System — 现代商务扁平
   白底 · 海军蓝/蓝/绿 · Poppins + Open Sans · 圆角卡片 · 无阴影渐变
   ============================================================ */

:root {
    --bg: #f8fafc;
    --card: #ffffff;
    --card-soft: #f1f5f9;
    --ink: #0f172a;
    --ink-2: #475569;
    --ink-3: #94a3b8;
    --line: #e2e8f0;
    --line-strong: #cbd5e1;
    --navy: #1e3a5f;
    --navy-deep: #142c4a;
    --navy-soft: #e8eef5;
    --blue: #2563eb;
    --blue-soft: #eff6ff;
    --green: #059669;
    --green-deep: #047857;
    --green-soft: #ecfdf5;
    --amber: #d97706;
    --amber-soft: #fffbeb;
    --white: #ffffff;

    --font-display: 'Poppins', 'Noto Sans SC', -apple-system, "PingFang SC", sans-serif;
    --font-body: 'Open Sans', 'Noto Sans SC', -apple-system, "PingFang SC", sans-serif;

    --radius: 14px;
    --radius-sm: 9px;
    --ease: cubic-bezier(0.4, 0, 0.2, 1);
    --t-fast: 0.16s var(--ease);
    --t-med: 0.28s var(--ease);

    --nav-height: 72px;
    --container-max: 1160px;
    --container-wide: 1340px;
    --space-sec: clamp(64px, 8vw, 112px);
}

/* ========== Reset ========== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.75;
    color: var(--ink);
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
strong { font-weight: 700; }

::selection { background: var(--navy); color: #fff; }

/* ========== 版心与章节 ========== */
.container { max-width: var(--container-max); margin: 0 auto; padding: 0 24px; }
.container-wide { max-width: var(--container-wide); margin: 0 auto; padding: 0 24px; }
main { padding-top: var(--nav-height); }

section { position: relative; }
.sec { padding: var(--space-sec) 0; }

/* 章节头：编号徽章 + 标签 + 标题 + 导语 */
.sec-head { margin-bottom: 48px; }
.sec-kicker {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 18px;
}
.sec-index {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 12px;
    color: var(--blue);
    background: var(--blue-soft);
    border: 1px solid #dbeafe;
    border-radius: var(--radius-sm);
    padding: 3px 10px;
    letter-spacing: 0.04em;
}
.sec-label {
    font-size: 12.5px;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--ink-2);
}
.sec-rule { flex: 1; height: 1px; background: var(--line); }
.sec-title {
    font-family: var(--font-display);
    font-weight: 700;
    letter-spacing: -0.015em;
    line-height: 1.22;
    font-size: clamp(26px, 3.2vw, 38px);
    color: var(--ink);
    text-wrap: balance;
}
.sec-title em { font-style: normal; color: var(--navy); }
.sec-lead {
    margin-top: 14px;
    font-size: 16px;
    line-height: 1.8;
    color: var(--ink-2);
    max-width: 640px;
}

/* ========== 导航 — 白底圆角胶囊 ========== */
.main-nav {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 1000;
    height: var(--nav-height);
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--line);
    transition: background var(--t-med), border-color var(--t-med);
}
.nav-container {
    max-width: var(--container-wide);
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px;
}
.logo { display: flex; align-items: center; }
.logo-image { display: flex; align-items: center; gap: 10px; }
.logo img { height: 30px; width: auto; }
.logo-brand {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 19px;
    letter-spacing: -0.01em;
    color: var(--navy);
}

.nav-links { display: flex; align-items: center; gap: 6px; }
.nav-links a {
    position: relative;
    font-size: 14.5px;
    font-weight: 600;
    color: var(--ink-2);
    padding: 9px 16px;
    border-radius: 999px;
    transition: all var(--t-fast);
}
.nav-links a:hover { color: var(--navy); background: var(--navy-soft); }
.nav-links a.active { color: #fff; background: var(--navy); }

.nav-right { display: flex; align-items: center; }
.language-switch { position: relative; }
.language-switch::after {
    content: ""; position: absolute;
    top: 100%; left: 0; right: 0; height: 12px;
}
.dropdown-trigger {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13.5px;
    font-weight: 600;
    color: var(--ink-2);
    padding: 8px 13px;
    border: 1px solid var(--line-strong);
    border-radius: 999px;
    background: var(--card);
    transition: all var(--t-fast);
}
.dropdown-trigger:hover { border-color: var(--blue); color: var(--blue); }
.dropdown-content {
    opacity: 0;
    visibility: hidden;
    position: absolute;
    top: calc(100% + 8px); right: 0;
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    min-width: 160px;
    box-shadow: 0 14px 34px rgba(15, 23, 42, 0.1);
    transform: translateY(-6px);
    transition: all 0.25s var(--ease);
    z-index: 10;
}
.language-switch:hover .dropdown-content,
.language-switch.show .dropdown-content {
    opacity: 1; visibility: visible; transform: translateY(0);
}
.dropdown-content a {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 11px 16px;
    font-size: 14px;
    font-weight: 600;
    color: var(--ink-2);
    border-bottom: 1px solid var(--line);
    transition: all var(--t-fast);
}
.dropdown-content a:last-child { border-bottom: none; }
.dropdown-content a:hover { background: var(--bg); color: var(--ink); }
.dropdown-content a.active { color: var(--blue); background: var(--blue-soft); }
.lang-code { font-size: 11px; opacity: 0.55; letter-spacing: 0.06em; }

/* ========== 页脚 — 浅底 + 深色底栏 ========== */
footer {
    background: var(--card);
    border-top: 1px solid var(--line);
    margin-top: auto;
}
.footer-container { max-width: var(--container-wide); margin: 0 auto; padding: 64px 24px 0; }
.footer-main {
    display: grid;
    grid-template-columns: 1.8fr 1fr 1fr 1.2fr;
    gap: 48px;
    padding-bottom: 48px;
    border-bottom: 1px solid var(--line);
}
.footer-brand { display: flex; flex-direction: column; gap: 16px; }
.footer-logo { display: flex; align-items: center; gap: 10px; }
.footer-logo img { height: 28px; width: auto; }
.footer-logo-text {
    font-family: var(--font-display);
    font-size: 18px;
    font-weight: 600;
    color: var(--navy);
}
.footer-description {
    font-size: 13.5px;
    line-height: 1.9;
    color: var(--ink-2);
    max-width: 340px;
}
.footer-group { display: flex; flex-direction: column; gap: 14px; }
.footer-group-title {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--ink-3);
    padding-bottom: 8px;
    border-bottom: 1px solid var(--line);
}
.footer-links-list { display: flex; flex-direction: column; gap: 9px; }
.footer-links-list li a {
    font-size: 14px;
    color: var(--ink-2);
    transition: all var(--t-fast);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}
.footer-links-list li a:hover { color: var(--blue); transform: translateX(3px); }
.footer-links-list li a::before {
    content: "";
    width: 14px; height: 1px;
    background: var(--blue);
    opacity: 0;
    transition: opacity var(--t-fast);
}
.footer-links-list li a:hover::before { opacity: 1; }
.footer-contact-item {
    font-size: 13.5px;
    line-height: 1.9;
    color: var(--ink-2);
}
.footer-contact-item strong {
    display: block;
    color: var(--ink);
    font-weight: 600;
    letter-spacing: 0.02em;
}
.footer-contact-item strong::after { content: ":"; }
.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    margin: 0 -24px;
    padding: 20px 24px;
    background: var(--navy);
    color: #cbd5e1;
}
.footer-copyright { font-size: 12.5px; }
.footer-copyright p { color: #cbd5e1; }
.footer-social { display: flex; gap: 10px; }
.footer-social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 38px;
    height: 38px;
    border: 1px solid rgba(203, 213, 225, 0.35);
    border-radius: 999px;
    color: #cbd5e1;
    font-size: 14px;
    transition: all var(--t-fast);
}
.footer-social-link:hover { border-color: #fff; color: #fff; background: rgba(255, 255, 255, 0.08); }

/* ========== 按钮 — 扁平圆角 ========== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 9px;
    height: 48px;
    padding: 0 28px;
    font-size: 15px;
    font-weight: 600;
    letter-spacing: 0.01em;
    border-radius: 999px;
    cursor: pointer;
    white-space: nowrap;
    transition: all var(--t-med);
    border: 1px solid transparent;
}
.btn i { font-size: 13px; transition: transform var(--t-fast); }
.btn:hover i { transform: translateX(4px); }
.btn-primary { background: var(--navy); color: #fff; }
.btn-primary:hover { background: var(--navy-deep); }
.btn-secondary {
    background: var(--card);
    color: var(--ink);
    border-color: var(--line-strong);
}
.btn-secondary:hover { border-color: var(--navy); color: var(--navy); background: var(--navy-soft); }
.btn-on-dark { background: #fff; color: var(--navy); }
.btn-on-dark:hover { background: #e2e8f0; }
.btn-outline-ink {
    background: transparent;
    color: #fff;
    border-color: rgba(255, 255, 255, 0.45);
}
.btn-outline-ink:hover { border-color: #fff; background: rgba(255, 255, 255, 0.08); }
.btn-green { background: var(--green); color: #fff; }
.btn-green:hover { background: var(--green-deep); }
.btn-lg { height: 54px; padding: 0 34px; font-size: 16px; }

/* ========== 通用小组件 ========== */
.chip {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    font-size: 12.5px;
    font-weight: 600;
    color: var(--ink-2);
    background: var(--card);
    border: 1px solid var(--line-strong);
    border-radius: 999px;
    padding: 5px 13px;
    white-space: nowrap;
}
.chip i { font-size: 11px; color: var(--green); }
.chip--blue i { color: var(--blue); }
.chip--amber i { color: var(--amber); }
.chip--soft { background: var(--green-soft); border-color: #a7f3d0; color: var(--green-deep); }

.status-dot { display: inline-block; width: 8px; height: 8px; border-radius: 50%; }
.dot-live { background: var(--green); box-shadow: 0 0 0 3px rgba(5, 150, 105, 0.14); }
.dot-beta { background: var(--amber); box-shadow: 0 0 0 3px rgba(217, 119, 6, 0.14); }

/* 卡片通用 */
.card {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    transition: border-color var(--t-fast), transform var(--t-fast);
}
.card:hover { border-color: var(--line-strong); }

/* ========== 响应式 ========== */
.mobile-menu-toggle { display: none; }

@media (max-width: 1024px) {
    :root { --nav-height: 64px; }
    .footer-main { grid-template-columns: 1fr 1fr; gap: 36px; }
    .container, .container-wide { padding: 0 20px; }
    .nav-container { padding: 0 20px; }
}

@media (max-width: 768px) {
    :root { --nav-height: 60px; }
    .nav-links {
        display: none;
        position: fixed;
        top: var(--nav-height);
        left: 0; right: 0;
        background: var(--card);
        border-bottom: 1px solid var(--line);
        padding: 12px 14px;
        flex-direction: column;
        align-items: stretch;
        gap: 4px;
    }
    .nav-links.active { display: flex; }
    .nav-links a { padding: 12px 16px; border-radius: var(--radius-sm); }
    .nav-links a.active { background: var(--navy); }
    .mobile-menu-toggle {
        display: flex;
        width: 44px; height: 44px;
        align-items: center; justify-content: center;
        margin-right: 4px;
    }
    .mobile-menu-toggle span {
        display: block;
        width: 20px; height: 2px;
        background: var(--ink);
        margin: 4px auto;
        border-radius: 2px;
        transition: all 0.3s;
    }
    .mobile-menu-toggle.active span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
    .mobile-menu-toggle.active span:nth-child(2) { opacity: 0; }
    .mobile-menu-toggle.active span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }
    .footer-container { padding: 48px 20px 0; }
    .footer-main { grid-template-columns: 1fr; gap: 30px; padding-bottom: 36px; }
    .footer-bottom { flex-direction: column; text-align: center; margin: 0 -20px; padding: 18px 20px; }
    .btn { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}