/* ============================================================
   deltaview 落地页 — 深色主题
   设计语言取自产品本体:窗口底色 #171b24、蓝 #56c4ff、紫 #b78cff、
   diff 绿 #4ec9b0 / 红 #f14c4c(与 gui/ui styles.css 对齐)。
   ============================================================ */

:root {
  --bg: #0c0f15;          /* 页面底 */
  --bg-raise: #10141c;    /* 交替 section */
  --paper: #171b24;       /* 产品窗口本色:卡片 / 终端 / 截图框 */
  --paper-2: #1e2430;     /* 悬停浮起 */
  --ink: #e8ebf2;
  --muted: #a6b0c3;
  --faint: #78829a;
  --line: #262d3b;        /* 产品 mock-line 同源 */
  --line-strong: #333c4e;
  --accent: #56c4ff;
  --accent-strong: #7dd2ff;
  --accent-ink: #052033;  /* 主按钮上的深字 */
  --accent-soft: rgba(86, 196, 255, 0.12);
  --accent-2: #b78cff;
  --ins: #4ec9b0;
  --del: #f14c4c;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 24px 64px -24px rgba(0, 0, 0, 0.75);
  --max: 1140px;
  --nav-h: 64px;
  --mono: ui-monospace, "Cascadia Mono", "JetBrains Mono", Consolas, monospace;
  color-scheme: dark;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  /* hero 光晕伪元素带负向外扩,窄屏防横向滚动 */
  overflow-x: clip;
  color: var(--ink);
  font-family: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.7;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  background:
    radial-gradient(1100px 480px at 50% -160px, rgba(86, 196, 255, 0.14), transparent 65%),
    radial-gradient(900px 420px at 88% 2%, rgba(183, 140, 255, 0.07), transparent 60%),
    var(--bg);
  background-repeat: no-repeat;
}

h1,
h2,
h3,
p,
figure,
blockquote {
  margin: 0;
}

p,
li,
h2 {
  text-wrap: pretty;
}

ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--accent-strong);
}

button,
input {
  font: inherit;
}

code {
  font-family: var(--mono);
  font-size: 0.92em;
  color: var(--ink);
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

::selection {
  background: rgba(86, 196, 255, 0.32);
  color: var(--ink);
}

.skip {
  position: absolute;
  left: 16px;
  top: -48px;
  z-index: 80;
  background: var(--paper);
  color: var(--ink);
  padding: 8px 12px;
  border-radius: 8px;
}

.skip:focus {
  top: 12px;
}

.wrap {
  width: min(var(--max), calc(100% - 48px));
  margin-inline: auto;
}

.icon {
  width: 20px;
  height: 20px;
  display: block;
  flex: none;
}

.kicker {
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.14em;
}

.lede {
  color: var(--muted);
  font-size: 17px;
}

/* ── 按钮 ─────────────────────────────────── */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  border-radius: 9px;
  border: 1px solid transparent;
  padding: 10px 18px;
  font-weight: 600;
  font-size: 15px;
  line-height: 1.3;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease, transform 0.15s ease;
}

.btn .icon {
  width: 18px;
  height: 18px;
}

.btn-primary {
  background: var(--accent);
  color: var(--accent-ink);
}

.btn-primary:hover {
  background: var(--accent-strong);
  color: var(--accent-ink);
  transform: translateY(-1px);
}

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

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent-strong);
  background: var(--accent-soft);
}

.btn-lg {
  padding: 13px 24px;
  font-size: 16px;
}

.btn-sm {
  padding: 7px 14px;
  font-size: 14px;
}

/* ── 导航 ─────────────────────────────────── */

.nav {
  position: sticky;
  top: 0;
  z-index: 60;
  height: var(--nav-h);
  border-bottom: 1px solid transparent;
  transition: background-color 0.2s ease, border-color 0.2s ease;
}

.nav.is-stuck {
  background: rgba(12, 15, 21, 0.86);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-bottom-color: var(--line);
}

.nav-inner {
  height: 100%;
  display: flex;
  align-items: center;
  gap: 28px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  color: var(--ink);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: 0.01em;
  text-decoration: none;
}

.brand .icon {
  width: 22px;
  height: 22px;
  color: var(--accent);
}

.nav-links {
  margin-left: 8px;
  display: flex;
  gap: 4px;
}

.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14.5px;
  padding: 7px 12px;
  border-radius: 8px;
  transition: color 0.15s ease, background-color 0.15s ease;
}

.nav-links a:hover {
  color: var(--ink);
  background: var(--paper-2);
}

.nav-end {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 10px;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  color: var(--muted);
  transition: color 0.15s ease, background-color 0.15s ease;
}

.icon-btn:hover {
  color: var(--ink);
  background: var(--paper-2);
}

.nav-toggle {
  display: none;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 8px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
}

.nav-toggle .i-close {
  display: none;
}

.nav.is-open .nav-toggle .i-open {
  display: none;
}

.nav.is-open .nav-toggle .i-close {
  display: block;
}

/* ── Hero ─────────────────────────────────── */

.hero {
  padding: 88px 0 24px;
  text-align: center;
}

.hero .kicker {
  margin-bottom: 18px;
}

.hero h1 {
  font-size: clamp(2.3rem, 5.2vw, 3.7rem);
  line-height: 1.18;
  font-weight: 800;
  letter-spacing: 0.01em;
}

.hero h1 em {
  font-style: normal;
  color: var(--accent);
}

.hero .lede {
  max-width: 44em;
  margin: 22px auto 0;
}

.hero-actions {
  margin-top: 32px;
  display: flex;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
}

.hero-meta {
  margin-top: 18px;
  color: var(--faint);
  font-size: 13.5px;
  letter-spacing: 0.02em;
}

.hero-shot {
  margin: 60px auto 0;
  width: min(1060px, 100%);
  position: relative;
}

.hero-shot::before {
  content: "";
  position: absolute;
  inset: -9% -14%;
  background: radial-gradient(closest-side, rgba(86, 196, 255, 0.16), transparent 72%);
  pointer-events: none;
}

.hero-shot img,
.fig-shot img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
  background: var(--paper);
}

.hero-shot img {
  border: 1px solid var(--line-strong);
  box-shadow: var(--shadow);
}

/* ── 原则 band ────────────────────────────── */

.band-paper {
  margin-top: 72px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--bg-raise);
}

.principles {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  padding: 44px 0;
}

.principle h3 {
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 6px;
}

.principle p {
  color: var(--muted);
  font-size: 13.5px;
  line-height: 1.65;
}

/* ── section 骨架 ─────────────────────────── */

.section {
  padding: 104px 0 0;
}

.section-alt {
  background: var(--bg-raise);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  margin-top: 104px;
  padding-top: 96px;
}

.section-head {
  text-align: center;
  max-width: 46em;
  margin: 0 auto 20px;
}

.section-head h2 {
  font-size: clamp(1.6rem, 3vw, 2.15rem);
  font-weight: 800;
  line-height: 1.3;
  margin-top: 10px;
}

.section-head p:not(.kicker) {
  color: var(--muted);
  margin-top: 14px;
  font-size: 16px;
}

/* ── 看它工作:图文三联 ────────────────────── */

.fig {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: 56px;
  align-items: center;
  margin-top: 72px;
}

.fig-flip .fig-copy {
  order: 2;
}

.fig-no {
  display: block;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0.12em;
  margin-bottom: 10px;
}

.fig-no::before {
  content: "— ";
  color: var(--faint);
}

.fig-copy h3 {
  font-size: 22px;
  font-weight: 700;
  line-height: 1.35;
}

.fig-copy p {
  margin-top: 14px;
  color: var(--muted);
  font-size: 15.5px;
}

.fig-shot {
  min-width: 0;
}

.fig-shot img {
  border: 1px solid var(--line-strong);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.35), 0 18px 48px -20px rgba(0, 0, 0, 0.65);
  transition: border-color 0.2s ease;
}

.fig-shot:hover img {
  border-color: color-mix(in srgb, var(--accent) 45%, var(--line-strong));
}

.fig-shot figcaption {
  margin-top: 12px;
  color: var(--faint);
  font-size: 13px;
  text-align: center;
}

/* ── 能力卡 ───────────────────────────────── */

.caps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: 44px;
  padding-bottom: 96px;
}

.cap {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px 22px 24px;
  transition: border-color 0.18s ease, transform 0.18s ease, background-color 0.18s ease;
}

.cap:hover {
  border-color: var(--line-strong);
  background: var(--paper-2);
  transform: translateY(-2px);
}

.cap-title {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 15.5px;
  font-weight: 700;
}

.cap-title .icon {
  width: 20px;
  height: 20px;
  color: var(--accent);
}

.cap p {
  margin-top: 10px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

/* ── 时间 band + 终端卡 ───────────────────── */

.band {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--bg-raise);
}

.band-grid {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: 56px;
  align-items: center;
  padding: 96px 0;
}

.band-grid h2 {
  font-size: clamp(1.6rem, 3vw, 2.15rem);
  font-weight: 800;
  line-height: 1.3;
  margin-top: 10px;
}

.band-grid .lede {
  margin-top: 14px;
  font-size: 15.5px;
}

.term {
  background: var(--paper);
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.term-bar {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 11px 14px;
  border-bottom: 1px solid var(--line);
  background: var(--paper-2);
}

.term-bar i {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--line-strong);
}

.term-bar i:nth-child(1) { background: var(--del); }
.term-bar i:nth-child(2) { background: #e0b34c; }
.term-bar i:nth-child(3) { background: var(--ins); }

.term-bar span {
  margin-left: 6px;
  color: var(--faint);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.06em;
}

.cmds {
  padding: 18px 20px 8px;
}

.cmds li {
  padding: 10px 0 14px;
}

.cmds li + li {
  border-top: 1px solid var(--line);
}

.cmds code {
  display: block;
  font-size: 13.5px;
  line-height: 1.6;
  color: var(--muted);
  word-break: break-all;
}

.cmds code::before {
  content: "❯ ";
  color: var(--ins);
}

.cmds code span {
  color: var(--accent-2);
}

.cmds p {
  margin-top: 6px;
  color: var(--faint);
  font-size: 13px;
}

/* ── 三步 ─────────────────────────────────── */

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: 44px;
}

.step {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px;
  background: transparent;
}

.step-no {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0.12em;
}

.step h3 {
  margin-top: 10px;
  font-size: 17px;
  font-weight: 700;
}

.step p {
  margin-top: 8px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

/* ── 下载 ─────────────────────────────────── */

.download {
  display: grid;
  grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
  gap: 56px;
  align-items: center;
  padding: 80px 0 96px;
}

.download h2 {
  font-size: clamp(1.6rem, 3vw, 2.15rem);
  font-weight: 800;
  margin-top: 10px;
}

.ver-label {
  margin-top: 10px;
  color: var(--muted);
  font-size: 14.5px;
}

.ticks {
  margin-top: 20px;
  display: grid;
  gap: 10px;
}

.ticks li {
  position: relative;
  padding-left: 28px;
  color: var(--muted);
  font-size: 14.5px;
}

.ticks li::before {
  content: "✓";
  position: absolute;
  left: 0;
  top: 0;
  color: var(--ins);
  font-weight: 700;
}

.download-side {
  background: var(--paper);
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  padding: 30px 30px 26px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 14px;
}

.download-side .btn {
  align-self: stretch;
  justify-content: center;
}

.file-name {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--faint);
}

.download-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 14px;
}

.fine {
  color: var(--faint);
  font-size: 12.5px;
  line-height: 1.65;
  border-top: 1px solid var(--line);
  padding-top: 14px;
  width: 100%;
}

/* ── 问答 ─────────────────────────────────── */

.faq {
  max-width: 780px;
  margin: 40px auto 96px;
  display: grid;
  gap: 10px;
}

.faq details {
  border: 1px solid var(--line);
  border-radius: 11px;
  background: var(--paper);
  transition: border-color 0.18s ease;
}

.faq details[open] {
  border-color: var(--line-strong);
}

.faq summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  cursor: pointer;
  list-style: none;
  border-radius: 11px;
}

.faq summary::-webkit-details-marker {
  display: none;
}

.faq summary h3 {
  font-size: 15.5px;
  font-weight: 600;
  flex: 1;
  min-width: 0;
}

.faq summary .icon {
  width: 18px;
  height: 18px;
  color: var(--faint);
  transition: transform 0.2s ease;
}

.faq details[open] summary .icon {
  transform: rotate(180deg);
  color: var(--accent);
}

.faq details p {
  padding: 0 20px 18px;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.75;
}

/* ── footer ───────────────────────────────── */

.footer {
  border-top: 1px solid var(--line);
  background: var(--bg-raise);
  padding: 56px 0 32px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
}

.footer-brand p {
  margin-top: 12px;
  color: var(--faint);
  font-size: 13.5px;
  max-width: 30em;
}

.footer h2 {
  font-size: 13px;
  font-weight: 700;
  color: var(--faint);
  letter-spacing: 0.1em;
  margin-bottom: 12px;
}

.footer li + li {
  margin-top: 8px;
}

.footer li a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
}

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

.footer-base {
  margin-top: 48px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  color: var(--faint);
  font-size: 13px;
}

/* ── 入场动画(site.js 加 .js 与 .is-in)───── */

html.js .reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ── 响应式 ───────────────────────────────── */

@media (max-width: 1024px) {
  .caps {
    grid-template-columns: repeat(2, 1fr);
  }

  .fig,
  .band-grid {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .fig-flip .fig-copy {
    order: 0;
  }

  .download {
    grid-template-columns: 1fr;
    gap: 36px;
  }
}

@media (max-width: 800px) {
  .nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    margin: 0;
    flex-direction: column;
    gap: 2px;
    padding: 10px 24px 16px;
    background: rgba(12, 15, 21, 0.96);
    -webkit-backdrop-filter: blur(12px);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--line);
  }

  .nav.is-open .nav-links {
    display: flex;
  }

  .nav-links a {
    padding: 11px 12px;
    font-size: 15.5px;
  }

  .principles {
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
  }

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

  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
  }

  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 560px) {
  .caps {
    grid-template-columns: 1fr;
  }

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

  .hero {
    padding-top: 64px;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }
}

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

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

  .btn,
  .cap,
  .fig-shot img {
    transition: none;
  }
}