/* ============================================================
   宇宙深潜 — 设计系统 Design Tokens
   冷青主题 / 零外链 / 中文系统字体栈
   ------------------------------------------------------------
   说明：本文件只定义变量、重置、排版、基础组件。
   页面级样式在 css/site.css。
   ============================================================ */

/* ---------- 1. Tokens ---------- */
:root {
    /* 底色：深空黑，带一点冷蓝倾向 */
    --ink-0: #04060b;
    --ink-1: #070a12;
    --ink-2: #0b0f1a;
    --ink-3: #101725;

    /* 面板 / 描边 / 分隔线（全部半透明，叠在深空底上才有层次） */
    --panel: rgba(140, 210, 240, .035);
    --panel-hi: rgba(140, 210, 240, .075);
    --line: rgba(120, 190, 220, .13);
    --line-soft: rgba(120, 190, 220, .07);
    --line-strong: rgba(120, 225, 255, .34);

    /* 文字层级 */
    --fg: #e7f2f8;
    --fg-dim: #a9bdc9;
    --fg-faint: #6f8494;

    /* 强调色：电光青 */
    --accent: #4de2ff;
    --accent-soft: rgba(77, 226, 255, .16);
    --accent-dim: #1b8ba6;
    --accent-ink: #04141a;

    /* 光效 */
    --glow-sm: 0 0 16px rgba(77, 226, 255, .22);
    --glow-md: 0 0 40px rgba(77, 226, 255, .26);
    --glow-inset: inset 0 1px 0 rgba(255, 255, 255, .06);

    /* 结构 */
    --radius-sm: 8px;
    --radius: 14px;
    --radius-lg: 20px;
    --maxw: 1180px;
    --pad: 32px;
    --nav-h: 64px;

    /* 字号梯度（用 clamp 做流体排版，少写媒体查询） */
    --fs-mono: clamp(.68rem, .62rem + .18vw, .76rem);
    --fs-body: clamp(.94rem, .9rem + .16vw, 1.02rem);
    --fs-lead: clamp(1.05rem, 1rem + .35vw, 1.2rem);
    --fs-h3: clamp(1.12rem, 1.05rem + .4vw, 1.3rem);
    --fs-h2: clamp(1.7rem, 1.35rem + 1.5vw, 2.6rem);
    --fs-h1: clamp(2.6rem, 1.8rem + 4vw, 5rem);

    /* 字体：中文系统栈优先，数字/代码走等宽 */
    --font-sans: "HarmonyOS Sans SC", "PingFang SC", "Microsoft YaHei UI",
                 "Microsoft YaHei", "Segoe UI", system-ui, -apple-system, sans-serif;
    --font-mono: "JetBrains Mono", "Cascadia Mono", "SF Mono", Consolas,
                 ui-monospace, "DejaVu Sans Mono", monospace;

    /* 动效 */
    --ease: cubic-bezier(.22, .61, .36, 1);
    --ease-out: cubic-bezier(.16, 1, .3, 1);
}

/* ---------- 2. Reset ---------- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    background-color: var(--ink-0);
    color: var(--fg);
    font-family: var(--font-sans);
    font-size: var(--fs-body);
    line-height: 1.75;
    letter-spacing: .01em;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
    overflow-x: hidden;
    min-height: 100vh;
}

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

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

button,
input {
    font: inherit;
    color: inherit;
}

::selection {
    background: var(--accent);
    color: var(--accent-ink);
}

/* 滚动条：细、暗、只在深色里露一点青 */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: var(--ink-0);
}

::-webkit-scrollbar-thumb {
    background: rgba(120, 190, 220, .18);
    border-radius: 99px;
    border: 2px solid var(--ink-0);
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(77, 226, 255, .4);
}

/* ---------- 3. 全场背景层 ---------- */
/* 细网格：科技感的地基，用两层渐变画线，比图省流量 */
.bg-grid {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    background-image:
        linear-gradient(to right, rgba(120, 190, 220, .055) 1px, transparent 1px),
        linear-gradient(to bottom, rgba(120, 190, 220, .055) 1px, transparent 1px);
    background-size: 88px 88px;
    mask-image: radial-gradient(120% 90% at 50% 0%, #000 0%, rgba(0, 0, 0, .55) 45%, transparent 82%);
    -webkit-mask-image: radial-gradient(120% 90% at 50% 0%, #000 0%, rgba(0, 0, 0, .55) 45%, transparent 82%);
}

/* 顶部冷光晕，避免整屏死黑 */
.bg-glow {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    background:
        radial-gradient(60% 45% at 50% -8%, rgba(77, 226, 255, .10) 0%, transparent 70%),
        radial-gradient(45% 40% at 88% 18%, rgba(52, 120, 255, .07) 0%, transparent 70%);
}

/* 颗粒感：一层极淡噪点，让深色不"塑料" */
.bg-grain {
    position: fixed;
    inset: 0;
    z-index: 1;
    pointer-events: none;
    opacity: .32;
    mix-blend-mode: overlay;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='140' height='140' filter='url(%23n)' opacity='.42'/%3E%3C/svg%3E");
}

/* ---------- 4. 布局 ---------- */
.wrap {
    width: 100%;
    max-width: var(--maxw);
    margin-inline: auto;
    padding-inline: var(--pad);
    position: relative;
    z-index: 2;
}

main {
    position: relative;
    z-index: 2;
}

.section {
    padding-block: clamp(72px, 9vw, 132px);
    position: relative;
}

.section--tight {
    padding-block: clamp(48px, 6vw, 88px);
}

/* 区块之间的发丝分隔线 */
.hr {
    height: 1px;
    border: 0;
    background: linear-gradient(to right, transparent, var(--line), transparent);
}

/* ---------- 5. 排版 ---------- */
.eyebrow {
    display: inline-flex;
    align-items: center;
    gap: .6em;
    font-family: var(--font-mono);
    font-size: var(--fs-mono);
    letter-spacing: .22em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 1.1em;
}

.eyebrow::before {
    content: "";
    width: 22px;
    height: 1px;
    background: var(--accent);
    box-shadow: var(--glow-sm);
}

.display {
    font-size: var(--fs-h1);
    font-weight: 300;
    line-height: 1.06;
    letter-spacing: -.02em;
}

.display strong {
    font-weight: 600;
    background: linear-gradient(100deg, #ffffff 0%, #bff2ff 42%, var(--accent) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2.title {
    font-size: var(--fs-h2);
    font-weight: 400;
    line-height: 1.24;
    letter-spacing: -.015em;
    color: #f2f9fc;
}

h3 {
    font-size: var(--fs-h3);
    font-weight: 500;
    line-height: 1.4;
}

.lead {
    font-size: var(--fs-lead);
    color: var(--fg-dim);
    line-height: 1.8;
    max-width: 68ch;
}

.prose {
    max-width: 68ch;
    color: var(--fg-dim);
}

.prose p + p {
    margin-top: 1em;
}

.prose strong,
.lead strong {
    color: var(--fg);
    font-weight: 600;
}

.accent {
    color: var(--accent);
}

.mono {
    font-family: var(--font-mono);
    font-variant-numeric: tabular-nums;
    letter-spacing: .02em;
}

/* 区块标题组：编号 + 标题 + 一句话说明 */
.sec-head {
    display: flex;
    align-items: flex-start;
    gap: clamp(16px, 2.4vw, 34px);
    margin-bottom: clamp(32px, 4vw, 56px);
}

.sec-head__idx {
    font-family: var(--font-mono);
    font-size: var(--fs-mono);
    letter-spacing: .18em;
    color: var(--accent);
    padding-top: .75em;
    white-space: nowrap;
    opacity: .85;
}

.sec-head__body {
    flex: 1;
    border-top: 1px solid var(--line);
    padding-top: clamp(12px, 1.6vw, 20px);
}

.sec-head__body .lead {
    margin-top: .7em;
}

/* ---------- 6. 顶部导航 ---------- */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-h);
    z-index: 100;
    display: flex;
    align-items: center;
    background: rgba(4, 6, 11, .72);
    -webkit-backdrop-filter: blur(14px) saturate(140%);
    backdrop-filter: blur(14px) saturate(140%);
    border-bottom: 1px solid var(--line-soft);
    transition: background .4s var(--ease), border-color .4s var(--ease);
}

.nav__inner {
    width: 100%;
    max-width: var(--maxw);
    margin-inline: auto;
    padding-inline: var(--pad);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-size: .98rem;
    letter-spacing: .06em;
    color: #f1f9fd;
}

.brand svg {
    width: 22px;
    height: 22px;
    color: var(--accent);
    filter: drop-shadow(0 0 8px rgba(77, 226, 255, .55));
}

.brand b {
    font-weight: 500;
}

.nav__links {
    display: flex;
    align-items: center;
    gap: clamp(14px, 2.2vw, 30px);
    list-style: none;
}

.nav__links a {
    font-family: var(--font-mono);
    font-size: var(--fs-mono);
    letter-spacing: .12em;
    color: var(--fg-dim);
    padding-block: 6px;
    position: relative;
    transition: color .3s var(--ease);
}

.nav__links a::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 1px;
    background: var(--accent);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform .35s var(--ease-out);
    box-shadow: var(--glow-sm);
}

.nav__links a:hover,
.nav__links a[aria-current="page"] {
    color: var(--fg);
}

.nav__links a:hover::after,
.nav__links a[aria-current="page"]::after {
    transform: scaleX(1);
}

/* 顶部滚动进度线 */
.scroll-progress {
    position: fixed;
    top: 0;
    left: 0;
    height: 2px;
    width: 100%;
    transform-origin: left;
    transform: scaleX(0);
    background: linear-gradient(to right, var(--accent-dim), var(--accent));
    box-shadow: 0 0 12px rgba(77, 226, 255, .6);
    z-index: 101;
    pointer-events: none;
}

/* ---------- 7. 卡片基础 ---------- */
.card {
    position: relative;
    background: linear-gradient(180deg, var(--panel-hi), var(--panel));
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: clamp(22px, 2.6vw, 32px);
    overflow: hidden;
    transition: border-color .45s var(--ease), transform .45s var(--ease-out),
                box-shadow .45s var(--ease);
}

/* 卡片顶部一道极细高光，模拟玻璃边缘 */
.card::before {
    content: "";
    position: absolute;
    inset: 0 0 auto 0;
    height: 1px;
    background: linear-gradient(to right, transparent, rgba(255, 255, 255, .18), transparent);
    opacity: .7;
}

.card:hover {
    border-color: var(--line-strong);
    box-shadow: 0 0 0 1px rgba(77, 226, 255, .06), 0 18px 60px -28px rgba(77, 226, 255, .5);
}

/* 四角刻度（科技仪表感） */
.card__ticks {
    position: absolute;
    inset: 8px;
    pointer-events: none;
    opacity: 0;
    transition: opacity .45s var(--ease);
}

.card:hover .card__ticks {
    opacity: 1;
}

.card__ticks span {
    position: absolute;
    width: 10px;
    height: 10px;
    border-color: var(--accent);
    border-style: solid;
    border-width: 0;
}

.card__ticks span:nth-child(1) { top: 0; left: 0; border-top-width: 1px; border-left-width: 1px; }
.card__ticks span:nth-child(2) { top: 0; right: 0; border-top-width: 1px; border-right-width: 1px; }
.card__ticks span:nth-child(3) { bottom: 0; left: 0; border-bottom-width: 1px; border-left-width: 1px; }
.card__ticks span:nth-child(4) { bottom: 0; right: 0; border-bottom-width: 1px; border-right-width: 1px; }

/* 图标槽：线性图标统一尺寸与描边 */
.icon {
    width: 34px;
    height: 34px;
    stroke: currentColor;
    fill: none;
    stroke-width: 1.4;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.icon-slot {
    width: 46px;
    height: 46px;
    display: grid;
    place-items: center;
    border: 1px solid var(--line);
    border-radius: 12px;
    color: var(--accent);
    background: rgba(77, 226, 255, .06);
    transition: color .4s var(--ease), border-color .4s var(--ease),
                background .4s var(--ease), box-shadow .4s var(--ease);
}

/* 标签 chip */
.chip-row {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.chip {
    font-family: var(--font-mono);
    font-size: .7rem;
    letter-spacing: .1em;
    color: var(--fg-faint);
    border: 1px solid var(--line);
    border-radius: 99px;
    padding: 3px 10px;
    transition: color .3s var(--ease), border-color .3s var(--ease);
}

/* ---------- 8. 按钮 ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: .7em;
    padding: 12px 22px;
    border-radius: 99px;
    border: 1px solid var(--line-strong);
    color: var(--accent);
    font-family: var(--font-mono);
    font-size: var(--fs-mono);
    letter-spacing: .14em;
    text-transform: uppercase;
    background: rgba(77, 226, 255, .05);
    transition: background .35s var(--ease), color .35s var(--ease),
                box-shadow .35s var(--ease), transform .35s var(--ease-out);
}

.btn:hover {
    background: var(--accent);
    color: var(--accent-ink);
    box-shadow: var(--glow-md);
}

.btn--ghost {
    border-color: var(--line);
    color: var(--fg-dim);
    background: transparent;
}

.btn--ghost:hover {
    color: var(--fg);
    border-color: var(--line-strong);
    background: rgba(77, 226, 255, .06);
    box-shadow: none;
}

.btn__arrow {
    transition: transform .35s var(--ease-out);
}

.btn:hover .btn__arrow {
    transform: translateX(4px);
}

/* ---------- 9. 页脚 ---------- */
.footer {
    position: relative;
    z-index: 2;
    border-top: 1px solid var(--line);
    padding-block: clamp(40px, 5vw, 64px) 40px;
    background: linear-gradient(180deg, transparent, rgba(77, 226, 255, .025));
}

.footer__row {
    display: flex;
    flex-wrap: wrap;
    gap: 20px 40px;
    justify-content: space-between;
    align-items: flex-end;
}

.footer__brand {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--fg-dim);
    font-size: .92rem;
}

.footer__brand svg {
    width: 18px;
    height: 18px;
    color: var(--accent-dim);
}

.footer__refs {
    font-family: var(--font-mono);
    font-size: .72rem;
    line-height: 1.9;
    letter-spacing: .04em;
    color: var(--fg-faint);
    max-width: 58ch;
    text-align: right;
}

.footer__meta {
    margin-top: 28px;
    padding-top: 20px;
    border-top: 1px solid var(--line-soft);
    display: flex;
    flex-wrap: wrap;
    gap: 8px 24px;
    justify-content: space-between;
    font-family: var(--font-mono);
    font-size: .7rem;
    letter-spacing: .1em;
    color: var(--fg-faint);
}

/* ---------- 10. 入场动效 ---------- */
/* 关键取舍：只有在 JS 运行时才隐藏内容（html.js），
   否则禁用 JS / 无 JS 环境下内容必须是可见的。 */
.js .reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity .9s var(--ease-out), transform .9s var(--ease-out);
    will-change: opacity, transform;
}

.js .reveal.is-in {
    opacity: 1;
    transform: none;
}

.js .reveal[data-delay="1"] { transition-delay: .09s; }
.js .reveal[data-delay="2"] { transition-delay: .18s; }
.js .reveal[data-delay="3"] { transition-delay: .27s; }
.js .reveal[data-delay="4"] { transition-delay: .36s; }

/* 尊重系统"减少动态效果" */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: .001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: .001ms !important;
    }

    .js .reveal {
        opacity: 1;
        transform: none;
    }
}

/* ---------- 11. 响应式 ---------- */
@media (max-width: 900px) {
    :root {
        --pad: 22px;
    }

    .sec-head {
        flex-direction: column;
        gap: 14px;
    }

    .sec-head__idx {
        padding-top: 0;
    }

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

    .footer__refs {
        text-align: left;
    }
}

@media (max-width: 640px) {
    :root {
        --pad: 18px;
        --nav-h: 58px;
    }

    body {
        line-height: 1.72;
    }

    .nav__links {
        gap: 12px;
    }

    .nav__links a {
        letter-spacing: .06em;
    }

    .nav__links li:not(:last-child) {
        display: none;
    }
}