:root {
    --bg: #f4f7fb;
    --surface: #ffffff;
    --surface-soft: #f8fbfd;
    --text: #1f2d3d;
    --text-soft: #627386;
    --border: rgba(54, 74, 96, 0.14);
    --accent: #1d73e8;
    --accent-strong: #165fc2;
    --accent-soft: rgba(29, 115, 232, 0.08);
    --teal: #0f9b8e;
    --amber: #b87512;
    --shadow: 0 14px 32px rgba(42, 59, 78, 0.08);
}

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

html {
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    padding-top: 84px;
    overflow-x: hidden;
    color: var(--text);
    background: var(--bg);
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;
    font-size: 15px;
    line-height: 1.72;
}

img {
    display: block;
    max-width: 100%;
}

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

button,
input,
textarea,
select {
    font: inherit;
}

button {
    border: 0;
    background: none;
    cursor: pointer;
}

ul,
ol {
    list-style: none;
}

.shell {
    width: min(1160px, calc(100% - 40px));
    margin: 0 auto;
}

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1000;
    width: 100%;
    border-bottom: 1px solid transparent;
    background: rgba(255, 255, 255, 0.90);
    backdrop-filter: blur(18px);
    transition: box-shadow 0.2s ease, background 0.2s ease;
}

.site-header.is-scrolled {
    background: rgba(255, 255, 255, 0.96);
    box-shadow: 0 8px 22px rgba(42, 59, 78, 0.06);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    height: 84px;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    min-width: 0;
}

.brand img {
    width: 38px;
    height: 38px;
    border-radius: 8px;
    box-shadow: 0 8px 18px rgba(29, 115, 232, 0.12);
}

.brand-copy {
    min-width: 0;
}

.brand-copy strong {
    display: block;
    color: var(--text);
    font-size: 17px;
    font-weight: 700;
    line-height: 1.2;
}

.brand-copy span {
    display: block;
    margin-top: 3px;
    color: var(--text-soft);
    font-size: 12px;
    font-weight: 600;
    line-height: 1.2;
}

.site-nav {
    display: flex;
    align-items: center;
    gap: 6px;
}

.site-nav a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 40px;
    padding: 0 14px;
    border-radius: 999px;
    color: var(--text-soft);
    font-size: 14px;
    font-weight: 600;
    transition: color 0.18s ease, background 0.18s ease, transform 0.18s ease;
}

.site-nav a:hover,
.site-nav a.active {
    color: var(--accent-strong);
    background: var(--accent-soft);
}

.site-nav .nav-download {
    color: #fff;
    background: var(--accent);
    box-shadow: 0 10px 20px rgba(29, 115, 232, 0.18);
}

.site-nav .nav-download:hover {
    color: #fff;
    background: var(--accent-strong);
    transform: translateY(-1px);
}

.nav-toggle {
    display: none;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 5px;
    width: 44px;
    height: 44px;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: #fff;
}

.nav-toggle span {
    width: 18px;
    height: 2px;
    border-radius: 999px;
    background: var(--text);
    transition: transform 0.2s ease, opacity 0.2s ease;
}

body.nav-open .nav-toggle span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

body.nav-open .nav-toggle span:nth-child(2) {
    opacity: 0;
}

body.nav-open .nav-toggle span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

.button-row {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 46px;
    padding: 0 18px;
    border-radius: 999px;
    font-size: 14px;
    font-weight: 700;
    transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

.button:hover {
    transform: translateY(-1px);
}

.button.primary {
    color: #fff;
    background: var(--accent);
    box-shadow: 0 12px 24px rgba(29, 115, 232, 0.18);
}

.button.primary:hover {
    background: var(--accent-strong);
}

.button.secondary {
    color: var(--text);
    border: 1px solid var(--border);
    background: #fff;
}

.button.secondary:hover {
    box-shadow: 0 10px 20px rgba(42, 59, 78, 0.08);
}

.eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 10px;
    color: var(--accent-strong);
    font-size: 12px;
    font-weight: 800;
    letter-spacing: 0.08em;
}

.eyebrow::before {
    content: "";
    width: 20px;
    height: 1px;
    background: currentColor;
}

.page-intro {
    display: grid;
    gap: 10px;
    margin-bottom: 28px;
}

.page-intro h1 {
    color: var(--text);
    font-size: clamp(24px, 3vw, 34px);
    line-height: 1.18;
    font-weight: 800;
}

.page-intro p {
    max-width: 66ch;
    color: var(--text-soft);
    font-size: 15px;
}

.tag-row {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.tag {
    display: inline-flex;
    align-items: center;
    min-height: 30px;
    padding: 0 11px;
    border-radius: 999px;
    border: 1px solid rgba(54, 74, 96, 0.12);
    background: rgba(255, 255, 255, 0.72);
    color: var(--text-soft);
    font-size: 12px;
    font-weight: 600;
}

.site-footer {
    margin-top: 32px;
    padding: 46px 0 26px;
    color: var(--text-soft);
    background: #eaf0f6;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.35fr repeat(3, minmax(0, 1fr));
    gap: 28px;
    align-items: start;
}

.footer-brand {
    display: grid;
    gap: 16px;
}

.footer-brand p,
.footer-section li,
.footer-section a,
.footer-bottom {
    color: var(--text-soft);
    font-size: 14px;
}

.footer-section {
    display: grid;
    gap: 12px;
}

.footer-section h4 {
    color: var(--text);
    font-size: 14px;
    font-weight: 800;
}

.footer-section ul {
    display: grid;
    gap: 8px;
}

.footer-section a:hover,
.footer-bottom a:hover {
    color: var(--accent-strong);
}

.footer-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    margin-top: 28px;
    padding-top: 22px;
    border-top: 1px solid rgba(54, 74, 96, 0.12);
}

.footer-bottom a {
    color: var(--text-soft);
}

.site-nav a:focus-visible,
.nav-toggle:focus-visible,
.button:focus-visible,
.brand:focus-visible,
.footer-section a:focus-visible {
    outline: 2px solid rgba(29, 115, 232, 0.35);
    outline-offset: 3px;
}

@media (max-width: 960px) {
    body {
        padding-top: 76px;
    }

    .header-inner {
        height: 76px;
    }

    .nav-toggle {
        display: inline-flex;
    }

    .site-nav {
        position: absolute;
        top: calc(100% + 10px);
        right: 20px;
        width: min(280px, calc(100% - 40px));
        flex-direction: column;
        align-items: stretch;
        padding: 14px;
        border-radius: 8px;
        border: 1px solid var(--border);
        background: rgba(255, 255, 255, 0.98);
        box-shadow: var(--shadow);
        opacity: 0;
        pointer-events: none;
        transform: translateY(-8px);
        transition: opacity 0.2s ease, transform 0.2s ease;
    }

    body.nav-open .site-nav {
        opacity: 1;
        pointer-events: auto;
        transform: translateY(0);
    }

    .site-nav a {
        width: 100%;
    }

    .site-nav .nav-download {
        width: fit-content;
        align-self: center;
        padding: 0 30px;
        margin-top: 4px;
    }

    .footer-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .footer-brand {
        grid-column: span 3;
    }
}

@media (max-width: 720px) {
    .shell {
        width: calc(100% - 28px);
    }

    .button-row {
        flex-direction: column;
        align-items: stretch;
    }

    .button {
        width: 100%;
    }

    .footer-bottom {
        flex-direction: column;
        align-items: flex-start;
    }
}

@media (max-width: 520px) {
    .brand-copy span {
        display: none;
    }

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

    .footer-brand {
        grid-column: auto;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation: none !important;
        transition: none !important;
    }
}