/* ============================================================
   纷享互联 — 全站共享样式
   设计语言：Precision Editorial × Industrial Tech
   配色：墨黑 × 暖白 × 灼热橙
   字体：思源宋体 × Instrument Serif × Manrope × JetBrains Mono
   ============================================================ */

:root {
    /* 配色 */
    --ink: #0a0a0a;
    --ink-2: #131313;
    --ink-3: #1c1c1c;
    --line: #262626;
    --line-2: #343434;
    --paper: #fafaf9;
    --bone: #f3efe7;
    --bone-2: #e8e3d8;
    --soot: #161616;
    --hot: #ff4d17;
    --hot-deep: #d63d0c;
    --mute: #707070;
    --mute-2: #a0a0a0;
    --mute-3: #c8c4bd;

    /* 字体 */
    --f-serif-cn: "Noto Serif SC", "Songti SC", "STSong", serif;
    --f-sans-cn: "Noto Sans SC", -apple-system, "PingFang SC", sans-serif;
    --f-serif-en: "Instrument Serif", "Times New Roman", serif;
    --f-sans-en: "Manrope", -apple-system, sans-serif;
    --f-mono: "JetBrains Mono", "SF Mono", "Consolas", monospace;

    /* 缓动 */
    --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ============ 基础 ============ */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: var(--f-sans-cn), var(--f-sans-en);
    background: var(--ink);
    color: var(--paper);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 噪声纹理覆盖层 */
body::before {
    content: "";
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 100;
    opacity: 0.04;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3' /%3E%3C/filter%3E%3Crect width='200' height='200' filter='url(%23n)' /%3E%3C/svg%3E");
    mix-blend-mode: overlay;
}

::selection { background: var(--hot); color: var(--paper); }

a { color: inherit; text-decoration: none; transition: color .3s var(--ease); }
a:hover { color: var(--hot); }

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

/* skip-link */
.skip-link {
    position: absolute;
    top: -60px;
    left: 0;
    background: var(--hot);
    color: var(--paper);
    padding: .6rem 1.2rem;
    z-index: 200;
    font-family: var(--f-sans-en);
    font-size: .85rem;
    font-weight: 600;
    transition: top .2s var(--ease);
}
.skip-link:focus { top: 0; }

/* ============ 导航 ============ */
.nav-bar {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 50;
    padding: 1.1rem 0;
    background: rgba(10,10,10,0.6);
    backdrop-filter: blur(24px) saturate(1.4);
    -webkit-backdrop-filter: blur(24px) saturate(1.4);
    border-bottom: 1px solid var(--line);
}
.nav-inner {
    max-width: 1440px;
    margin: 0 auto;
    padding: 0 2.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.nav-logo {
    display: flex;
    align-items: center;
    gap: .7rem;
    font-family: var(--f-serif-cn);
    font-weight: 700;
    font-size: 1.35rem;
    letter-spacing: -0.01em;
    color: var(--paper);
}
.nav-logo-mark {
    width: 32px; height: 32px;
    display: grid; place-items: center;
    background: var(--hot);
    border-radius: 6px;
    font-family: var(--f-serif-en);
    font-style: italic;
    color: var(--ink);
    font-size: 1.1rem;
    font-weight: 600;
    transform: rotate(-4deg);
    transition: transform .4s var(--ease);
}
.nav-logo:hover .nav-logo-mark { transform: rotate(4deg) scale(1.05); }

.nav-links {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    list-style: none;
}
.nav-links a {
    display: inline-block;
    padding: 0.5rem 0.95rem;
    font-size: 0.86rem;
    font-weight: 500;
    color: var(--mute-3);
    border-radius: 999px;
    transition: all .3s var(--ease);
}
.nav-links a:hover { color: var(--paper); background: var(--ink-3); }
.nav-links a.active {
    color: var(--paper);
    border-bottom: 2px solid var(--hot);
    padding-bottom: calc(0.5rem - 2px);
}

.nav-cta {
    font-family: var(--f-sans-en);
    display: inline-flex;
    align-items: center;
    gap: .5rem;
    padding: .65rem 1.3rem;
    background: var(--paper);
    color: var(--ink);
    border-radius: 999px;
    font-size: 0.86rem;
    font-weight: 600;
    transition: all .3s var(--ease);
}
.nav-cta:hover { background: var(--hot); color: var(--paper); transform: translateY(-1px); }
.nav-cta .dot {
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--hot);
    animation: sf-pulse 2s var(--ease) infinite;
}
@keyframes sf-pulse {
    0%, 100% { transform: scale(1); opacity: 1; }
    50% { transform: scale(1.6); opacity: .5; }
}

.nav-toggle { display: none; background: none; border: 0; color: var(--paper); font-size: 1.5rem; cursor: pointer; }
.nav-mobile {
    display: none;
    flex-direction: column;
    gap: .3rem;
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--line);
    background: var(--ink-2);
}
.nav-mobile a { padding: .7rem .5rem; color: var(--mute-3); font-size: .95rem; border-bottom: 1px solid var(--line); }
.nav-mobile a.active, .nav-mobile a[aria-current="page"] { color: var(--hot); }

/* ============ 按钮 ============ */
.btn-primary-x {
    display: inline-flex;
    align-items: center;
    gap: .8rem;
    padding: 1.05rem 1.8rem;
    background: var(--hot);
    color: var(--paper);
    border-radius: 999px;
    font-family: var(--f-sans-en);
    font-weight: 600;
    font-size: 0.95rem;
    transition: all .35s var(--ease);
    box-shadow: 0 8px 32px rgba(255,77,23,0.25);
    border: 0;
    cursor: pointer;
}
.btn-primary-x:hover {
    transform: translateY(-2px);
    background: var(--hot-deep);
    color: var(--paper);
    box-shadow: 0 12px 40px rgba(255,77,23,0.4);
}
.btn-primary-x .arrow { transition: transform .35s var(--ease); }
.btn-primary-x:hover .arrow { transform: translateX(4px); }

.btn-ghost-x {
    display: inline-flex;
    align-items: center;
    gap: .6rem;
    padding: 1.05rem 1.5rem;
    color: var(--paper);
    font-family: var(--f-sans-en);
    font-weight: 500;
    font-size: 0.95rem;
    border: 1px solid var(--line-2);
    border-radius: 999px;
    transition: all .3s var(--ease);
    background: transparent;
    cursor: pointer;
}
.btn-ghost-x:hover { border-color: var(--hot); color: var(--hot); }

/* ============ 章节通用 ============ */
section { position: relative; }
.sec { padding: 8rem 2.5rem; }
.sec-inner { max-width: 1440px; margin: 0 auto; }

.sec-head {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 3rem;
    align-items: start;
    margin-bottom: 5rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--line);
}
.sec-num {
    font-family: var(--f-mono);
    font-size: 0.8rem;
    color: var(--hot);
    letter-spacing: 0.2em;
    display: flex;
    align-items: center;
    gap: .8rem;
    padding-top: .8rem;
    white-space: nowrap;
}
.sec-num::before {
    content: "";
    width: 24px; height: 1px;
    background: var(--hot);
}
.sec-title {
    font-family: var(--f-serif-cn);
    font-weight: 700;
    font-size: clamp(2.2rem, 4.5vw, 3.6rem);
    line-height: 1.1;
    letter-spacing: -0.02em;
    color: var(--paper);
}
.sec-title em {
    font-family: var(--f-serif-en);
    font-style: italic;
    font-weight: 400;
    color: var(--hot);
}
.sec-subtitle {
    margin-top: 1.2rem;
    font-size: 1rem;
    color: var(--mute-2);
    max-width: 50ch;
    line-height: 1.7;
}

/* ============ Footer ============ */
.footer {
    background: var(--ink-2);
    padding: 5rem 2.5rem 2rem;
    border-top: 1px solid var(--line);
}
.footer-inner { max-width: 1440px; margin: 0 auto; }
.footer-top {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1.2fr;
    gap: 3rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid var(--line);
}
.footer-brand { display: flex; flex-direction: column; gap: 1.2rem; }
.footer-logo {
    display: flex;
    align-items: center;
    gap: .8rem;
    font-family: var(--f-serif-cn);
    font-weight: 700;
    font-size: 1.3rem;
}
.footer-tagline {
    color: var(--mute-2);
    font-size: 0.92rem;
    line-height: 1.7;
    max-width: 30ch;
}
.footer-col h4 {
    font-family: var(--f-mono);
    font-size: 0.72rem;
    color: var(--mute);
    text-transform: uppercase;
    letter-spacing: 0.2em;
    margin-bottom: 1.5rem;
    font-weight: 500;
}
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: .8rem; }
.footer-col a { color: var(--mute-3); font-size: 0.92rem; }
.footer-col a:hover { color: var(--hot); }
.footer-contact li {
    display: flex;
    align-items: flex-start;
    gap: .8rem;
    color: var(--mute-3);
    font-size: 0.9rem;
    line-height: 1.6;
}
.footer-contact .ico { color: var(--hot); margin-top: .2rem; flex-shrink: 0; }
.footer-bottom {
    padding-top: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    font-family: var(--f-mono);
    font-size: 0.76rem;
    color: var(--mute);
    letter-spacing: 0.05em;
}
.footer-bottom .icp a { color: var(--mute); }
.footer-bottom .icp a:hover { color: var(--hot); }

/* ============ Reveal 动画 ============ */
.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity .9s var(--ease), transform .9s var(--ease);
}
.reveal.in { opacity: 1; transform: translateY(0); }
.reveal.d1 { transition-delay: 0.1s; }
.reveal.d2 { transition-delay: 0.2s; }
.reveal.d3 { transition-delay: 0.3s; }
.reveal.d4 { transition-delay: 0.4s; }

/* ============ 响应式 ============ */
@media (max-width: 1024px) {
    .sec-head { grid-template-columns: 1fr; gap: 1.5rem; }
    .footer-top { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 720px) {
    .nav-links, .nav-cta { display: none; }
    .nav-toggle { display: block; }
    .nav-mobile { display: none; }
    .nav-mobile.open { display: flex; }
    .nav-mobile.closed { display: none; }
    .sec { padding: 5rem 1.5rem; }
    .footer-top { grid-template-columns: 1fr; }
    .footer { padding: 4rem 1.5rem 2rem; }
}

/* prefers-reduced-motion */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { animation: none !important; transition: none !important; }
    .reveal { opacity: 1; transform: none; }
}