/*
 * Kelumen 站点视觉。
 * 只使用一种强调色（海军蓝）和中性纸色，不用渐变、圆角卡片和图标栅格。
 * 英文正文用系统无衬线字体，不加载外链字体。
 */

:root {
  --bg: #f7f7f5;
  --bg-2: #ffffff;
  --ink: #141619;
  --muted: #3a404a;
  --soft: #4e5864;
  --line: #e3e3de;
  --line-strong: #c9c9c2;
  --navy: #0f2f4c;
  --navy-2: #163e62;
  --on-navy: #f4f6f8;
  --on-navy-soft: #c5d0da;
  --sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  --wrap: 1080px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1.0625rem;
  line-height: 1.6;
  text-rendering: optimizeLegibility;
}

::selection { background: #d5e0ea; }

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

h1, h2, h3, p { text-wrap: pretty; }

h1, h2, h3 {
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.01em;
}

p { margin: 0; }

a { color: var(--navy); }

.wrap {
  width: min(var(--wrap), calc(100% - 3rem));
  margin-inline: auto;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 30;
  background: var(--ink);
  color: var(--bg);
  padding: 0.45rem 0.75rem;
  text-decoration: none;
}

.skip:focus { top: 0.6rem; }

/* 顶栏保持实色。粘住是为了长页导航，不做成玻璃拟态。 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--bg);
  border-top: 3px solid var(--navy);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 4.25rem;
  gap: 1.5rem;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 600;
  font-size: 1.2rem;
  letter-spacing: 0.01em;
  line-height: 1;
}

/* 专有词不要在汉字中间断开，例如「上线责任」被拆成行尾一个「上」。 */
.keep { white-space: nowrap; }

.mark { color: var(--navy); flex: none; }

.nav {
  display: flex;
  align-items: center;
  gap: 1.6rem;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.98rem;
  padding: 0.35rem 0;
}

.nav a[aria-current="page"] {
  color: var(--ink);
  box-shadow: inset 0 -1px 0 var(--ink);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.5rem;
  min-height: 2.75rem;
  padding: 0 0.15rem;
  border: 0;
  background: transparent;
  color: var(--ink);
  font: inherit;
  cursor: pointer;
}

.nav-toggle-bars,
.nav-toggle-bars::before,
.nav-toggle-bars::after {
  display: block;
  width: 1.05rem;
  height: 1px;
  background: currentColor;
  content: "";
}

.nav-toggle-bars { position: relative; }

.nav-toggle-bars::before,
.nav-toggle-bars::after {
  position: absolute;
  left: 0;
}

.nav-toggle-bars::before { top: -5px; }
.nav-toggle-bars::after { top: 5px; }

.kicker {
  margin: 0;
  color: var(--navy);
  font-size: 0.92rem;
  font-weight: 600;
}

.lede {
  color: var(--muted);
  max-width: 40rem;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(16rem, 0.78fr);
  gap: 4rem;
  align-items: center;
  padding: 4.4rem 0 2.6rem;
}

.hero h1 {
  margin: 0.7rem 0 1rem;
  font-size: clamp(2.05rem, 3.5vw, 2.85rem);
  line-height: 1.15;
}

.hero .lede { margin-bottom: 1.6rem; }

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.85rem;
  padding: 0.45rem 1.15rem;
  background: var(--navy);
  color: var(--on-navy);
  text-decoration: none;
  font-size: 0.98rem;
}

.button:hover { background: var(--navy-2); }

.button-ghost {
  background: transparent;
  color: var(--navy);
  box-shadow: inset 0 0 0 1px var(--navy);
}

.button-ghost:hover { background: rgba(15, 47, 76, 0.05); }

/* 范围备忘是说明，不是成绩单。白底细框，避免卡片阴影。 */
.dossier {
  border: 1px solid var(--line-strong);
  background: var(--bg-2);
  padding: 1.15rem 1.25rem 0.35rem;
}

.dossier-kicker {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 0 0 0.35rem;
  color: var(--soft);
  font-size: 0.82rem;
}

.dossier dl { margin: 0; }

.dossier dl > div {
  display: grid;
  grid-template-columns: 6.75rem 1fr;
  gap: 0.85rem;
  padding: 0.8rem 0;
  border-top: 1px solid var(--line);
}

.dossier dt { color: var(--soft); }
.dossier dd { margin: 0; }

.meta-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin: 0;
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}

.meta-row > div { padding: 1.15rem 1.5rem 1.15rem 0; }

.meta-row > div + div {
  padding-left: 1.5rem;
  border-left: 1px solid var(--line);
}

.meta-row dt {
  color: var(--soft);
  font-size: 0.86rem;
}

.meta-row dd {
  margin: 0.15rem 0 0;
  font-weight: 600;
}

.principles {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding-top: 0.25rem;
  padding-bottom: 0.5rem;
}

.principles article { padding: 2rem 1.75rem 1.5rem 0; }

.principles article + article {
  padding-left: 1.75rem;
  border-left: 1px solid var(--line);
}

.idx {
  margin: 0 0 0.7rem;
  color: var(--navy);
  font-size: 0.92rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.08em;
}

.principles h3 {
  margin: 0 0 0.4rem;
  font-size: 1.15rem;
}

.principles p:last-child { color: var(--muted); }

.section { padding-top: 3.4rem; }

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 0.35rem;
}

.section-head h2 {
  margin: 0;
  font-size: 1.35rem;
}

.text-link {
  color: var(--navy);
  text-underline-offset: 0.18em;
}

.teasers {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr 1fr;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-strong);
}

.teasers li {
  padding: 1.35rem 2rem 1.35rem 0;
  border-bottom: 1px solid var(--line);
}

.teasers li:nth-child(odd) {
  padding-right: 2.25rem;
  border-right: 1px solid var(--line);
}

.teasers li:nth-child(even) { padding-left: 2.25rem; }

.teasers h3 {
  margin: 0 0 0.3rem;
  font-size: 1.05rem;
}

.teasers p { color: var(--muted); }

.band {
  margin-top: 3.8rem;
  background: var(--navy);
  color: var(--on-navy);
}

.band-inner { padding: 4.2rem 0; }

.band h2 {
  margin: 0 0 0.9rem;
  max-width: 16em;
  font-size: clamp(1.7rem, 3vw, 2.4rem);
  line-height: 1.32;
  letter-spacing: 0;
}

.band p {
  max-width: 36rem;
  color: var(--on-navy-soft);
}

.cta {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 2rem;
  padding: 3rem 0 0.5rem;
}

.cta h2 {
  margin: 0 0 0.45rem;
  font-size: clamp(1.45rem, 2.4vw, 1.85rem);
  max-width: 16em;
}

.cta p { color: var(--muted); max-width: 32rem; }

.page-head { padding: 3.6rem 0 1.4rem; }

.page-head h1 {
  margin: 0.55rem 0 0.9rem;
  max-width: 18em;
  font-size: clamp(1.85rem, 3.2vw, 2.55rem);
  line-height: 1.2;
}

.work-list {
  list-style: none;
  counter-reset: step;
  margin: 0.5rem 0 0;
  padding: 0;
}

.work-list > li {
  counter-increment: step;
  display: grid;
  grid-template-columns: 4.25rem 1fr;
  gap: 0.5rem 1rem;
  padding: 1.7rem 0;
  border-top: 1px solid var(--line);
}

.work-list > li::before {
  content: counter(step, decimal-leading-zero);
  color: var(--navy);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.06em;
  padding-top: 0.2rem;
}

.work-list h2 {
  margin: 0 0 0.35rem;
  font-size: 1.22rem;
}

.work-list p { color: var(--muted); max-width: 42rem; }

.refuse {
  margin: 1rem 0 0;
  padding-top: 0.4rem;
}

.refuse h2 { margin: 1.2rem 0 0.7rem; font-size: 1.22rem; }

.refuse ul, .split ul, .checklist {
  margin: 0;
  padding-left: 1.15rem;
  color: var(--muted);
}

.refuse li + li,
.split li + li,
.checklist li + li { margin-top: 0.35rem; }

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  margin-top: 2.4rem;
  padding-bottom: 0.5rem;
}

.split section {
  background: var(--bg-2);
  border: 1px solid var(--line-strong);
  padding: 1.35rem 1.4rem 1.2rem;
}

.split h2 {
  margin: 0 0 0.75rem;
  font-size: 1.12rem;
}

/* 宽度限制放在段落上，不能放在带 .wrap 的 section 上，否则整块会在页面里居中，和标题左边错开。 */
.about-body > p,
.facts,
.next-step h2,
.next-step p { max-width: 40rem; }

.about-body > p + p { margin-top: 1rem; }

.facts { margin: 2rem 0 0; }

.facts > div {
  display: grid;
  grid-template-columns: 8.25rem 1fr;
  gap: 1rem;
  padding: 0.9rem 0;
  border-top: 1px solid var(--line);
}

.facts dt { color: var(--soft); }
.facts dd { margin: 0; }

.next-step {
  margin-top: 2.6rem;
  padding-top: 1.8rem;
  border-top: 1px solid var(--line-strong);
}

.next-step h2 { margin: 0 0 0.45rem; font-size: 1.3rem; }
.next-step p { color: var(--muted); margin-bottom: 1.15rem; }

.contact-block { padding-bottom: 1rem; }

.contact-label {
  margin: 0 0 0.35rem;
  color: var(--soft);
  font-size: 0.92rem;
}

.email-link {
  display: inline-block;
  margin-bottom: 1.5rem;
  color: var(--ink);
  font-size: clamp(1.7rem, 3.4vw, 2.5rem);
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.25;
  text-decoration: none;
  border-bottom: 1px solid var(--line-strong);
}

.email-link:hover { border-bottom-color: var(--ink); }

.checklist { margin-bottom: 1.5rem; }

.site-footer {
  margin-top: 4rem;
  border-top: 1px solid var(--line-strong);
  padding: 2rem 0 2.4rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 0.7fr 1fr;
  gap: 2rem;
}

.footer-name {
  margin: 0 0 0.35rem;
  font-weight: 600;
}

.footer-tag,
.legal,
.footer-label { color: var(--soft); }

.footer-label { margin: 0 0 0.25rem; font-size: 0.86rem; }

.footer-nav {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.25rem;
}

.footer-nav a,
.footer-mail {
  color: var(--ink);
  text-decoration: none;
}

.footer-nav a:hover,
.footer-mail:hover { text-decoration: underline; text-underline-offset: 0.18em; }

.legal {
  margin: 1.8rem auto 0;
  font-size: 0.9rem;
}

@media (max-width: 860px) {
  .nav-toggle { display: inline-flex; }

  .header-inner { position: relative; }

  .nav {
    display: none;
    position: absolute;
    left: calc(50% - 50vw);
    right: calc(50% - 50vw);
    top: calc(100% + 1px);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0.25rem 1.5rem 0.8rem;
    background: var(--bg);
    border-bottom: 1px solid var(--line-strong);
  }

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

  .nav a {
    padding: 0.8rem 0;
    border-top: 1px solid var(--line);
  }

  .hero,
  .principles,
  .split,
  .footer-grid,
  .meta-row,
  .teasers {
    grid-template-columns: 1fr;
  }

  .principles article,
  .principles article + article,
  .meta-row > div,
  .meta-row > div + div,
  .teasers li,
  .teasers li:nth-child(odd),
  .teasers li:nth-child(even) {
    padding-left: 0;
    padding-right: 0;
    border-left: 0;
    border-right: 0;
  }

  .principles article + article,
  .meta-row > div + div { border-top: 1px solid var(--line); }

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

@media (max-width: 640px) {
  .wrap { width: min(var(--wrap), calc(100% - 2rem)); }

  .hero { padding-top: 2.6rem; gap: 2rem; }

  .work-list > li,
  .facts > div,
  .dossier dl > div { grid-template-columns: 1fr; gap: 0.2rem; }

  .page-head { padding-top: 2.4rem; }
}

@media print {
  .site-header, .nav-toggle, .skip, .actions, .button { display: none !important; }
  .site-header { position: static; }
  body { background: #fff; }
  a { color: inherit; text-decoration: none; }
}