/* ============================================================
   EXTRACUT — knowledge.css
   「Solutions & How-To」应用知识库专用样式（唯一来源）
   依赖 industrial.css 的设计令牌（--ink-* / --accent-* / --space-* / --ease-*）
   ============================================================ */

.kn-page {
  --kn-anchor: 148px;   /* navbar 76 + rail 62 + 10 */
  --kn-col: 1120px;
  background: var(--bg-primary);
}

/* ---------- HERO ---------- */
.kn-hero {
  position: relative;
  overflow: hidden;
  background: var(--ink-900);
  color: #fff;
  padding: 72px 0 0;
}
.kn-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.035) 1px, transparent 1px);
  background-size: 64px 64px;
  -webkit-mask-image: radial-gradient(120% 90% at 20% 0%, #000 0%, transparent 72%);
  mask-image: radial-gradient(120% 90% at 20% 0%, #000 0%, transparent 72%);
  pointer-events: none;
}
.kn-hero::after {
  content: "";
  position: absolute;
  top: -120px;
  right: -140px;
  width: 520px;
  height: 520px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(230, 57, 70, 0.20) 0%, transparent 68%);
  pointer-events: none;
}
.kn-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(0, 0.85fr);
  gap: 56px;
  align-items: center;
  padding-bottom: 56px;
}
.kn-crumbs {
  font: 500 12px/1 var(--font-body);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.5);
  margin-bottom: 22px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.kn-crumbs a { color: rgba(255, 255, 255, 0.72); text-decoration: none; transition: color var(--d-fast) var(--ease-out); }
.kn-crumbs a:hover { color: #fff; }
.kn-crumbs span { color: rgba(255, 255, 255, 0.28); }
.kn-crumbs em { font-style: normal; color: var(--accent-red-light); }

.kn-hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font: 700 11px/1 var(--font-body);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-red-light);
  margin-bottom: 18px;
}
.kn-hero-eyebrow::before {
  content: "";
  width: 26px;
  height: 2px;
  background: var(--accent-red);
  display: block;
}
.kn-hero-num {
  position: absolute;
  top: 14px;
  right: 0;
  font: 800 132px/1 var(--font-mono);
  letter-spacing: -0.05em;
  color: rgba(255, 255, 255, 0.055);
  pointer-events: none;
  user-select: none;
}
.kn-hero-title {
  font: 800 clamp(34px, 4.4vw, 58px) / 1.06 var(--font-display);
  letter-spacing: -0.035em;
  margin: 0 0 20px;
  max-width: 15ch;
}
.kn-hero-title em { font-style: normal; color: var(--accent-red-light); }
.kn-hero-sub {
  font: 400 17px/1.65 var(--font-body);
  color: rgba(255, 255, 255, 0.68);
  max-width: 62ch;
  margin: 0;
}

/* hero 关键指标条 */
.kn-stats {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 1px solid rgba(255, 255, 255, 0.12);
}
.kn-stat {
  padding: 24px 26px 28px;
  border-right: 1px solid rgba(255, 255, 255, 0.10);
}
.kn-stat:last-child { border-right: 0; }
.kn-stat-num {
  font: 700 21px/1.1 var(--font-mono);
  letter-spacing: -0.02em;
  color: #fff;
  margin-bottom: 8px;
}
.kn-stat-num em { font-style: normal; color: var(--accent-red-light); }
.kn-stat-label {
  font: 600 11px/1.35 var(--font-body);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.46);
}

/* hero 右侧技术图号块 */
.kn-hero-fig {
  position: relative;
  z-index: 1;
  justify-self: end;
  width: 100%;
  max-width: 300px;
  aspect-ratio: 1 / 1;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: var(--r-xl);
  background:
    linear-gradient(150deg, rgba(255, 255, 255, 0.045) 0%, rgba(255, 255, 255, 0) 62%),
    rgba(255, 255, 255, 0.02);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 34px;
}
.kn-hero-fig svg { width: 100%; height: auto; color: rgba(255, 255, 255, 0.9); }
.kn-hero-fig-cap {
  position: absolute;
  left: 20px;
  bottom: 16px;
  font: 700 10px/1 var(--font-mono);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.38);
}
.kn-hero-fig-cap em { font-style: normal; color: var(--accent-red-light); }

/* ---------- STICKY PAGE NAV ---------- */
.kn-rail {
  position: sticky;
  top: 76px;
  z-index: 40;
  background: rgba(255, 255, 255, 0.94);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--ink-100);
}
.kn-rail-inner {
  display: flex;
  align-items: center;
  gap: 4px;
  height: 62px;
  overflow-x: auto;
  scrollbar-width: none;
}
.kn-rail-inner::-webkit-scrollbar { display: none; }
.kn-rail-label {
  font: 700 10.5px/1 var(--font-body);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-400);
  padding-right: 16px;
  margin-right: 12px;
  border-right: 1px solid var(--ink-100);
  flex: 0 0 auto;
}
.kn-rail a {
  flex: 0 0 auto;
  font: 600 13px/1 var(--font-body);
  color: var(--ink-500);
  text-decoration: none;
  padding: 9px 14px;
  border-radius: var(--r-pill);
  white-space: nowrap;
  transition: all var(--d-fast) var(--ease-out);
}
.kn-rail a:hover { background: var(--ink-50); color: var(--ink-900); }
.kn-rail a.is-active { background: var(--ink-900); color: #fff; }

/* ---------- SECTION ---------- */
.kn-section {
  padding: 76px 0;
  border-bottom: 1px solid var(--ink-100);
  scroll-margin-top: var(--kn-anchor);
}
.kn-section:nth-child(even) { background: var(--bg-secondary); }
.kn-section:last-of-type { border-bottom: 0; }
.kn-sec-head { margin-bottom: 34px; max-width: 78ch; }
.kn-sec-eyebrow {
  display: flex;
  align-items: center;
  gap: 10px;
  font: 700 11px/1 var(--font-mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-red);
  margin-bottom: 14px;
}
.kn-sec-eyebrow::after {
  content: "";
  flex: 1 1 auto;
  max-width: 60px;
  height: 1px;
  background: var(--ink-200);
}
.kn-sec-title {
  font: 800 clamp(24px, 2.6vw, 34px) / 1.14 var(--font-display);
  letter-spacing: -0.028em;
  color: var(--ink-900);
  margin: 0 0 12px;
}
.kn-sec-desc {
  font: 400 16px/1.7 var(--font-body);
  color: var(--ink-500);
  margin: 0;
}

/* ---------- QUICK ANSWER CARDS ---------- */
.kn-quick { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; }
.kn-quick-card {
  background: #fff;
  border: 1px solid var(--ink-100);
  border-radius: var(--r-lg);
  padding: 28px 26px 26px;
  position: relative;
  transition: all var(--d-base) var(--ease-out);
}
.kn-quick-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}
.kn-quick-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--r-md);
  background: var(--ink-50);
  color: var(--accent-red);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
}
.kn-quick-title {
  font: 700 17px/1.3 var(--font-display);
  letter-spacing: -0.015em;
  color: var(--ink-900);
  margin: 0 0 10px;
}
.kn-quick-text {
  font: 400 14.5px/1.68 var(--font-body);
  color: var(--ink-500);
  margin: 0;
}
.kn-quick-text strong { color: var(--ink-900); font-weight: 600; }

/* ---------- TABLE ---------- */
.kn-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--ink-100);
  border-radius: var(--r-lg);
  background: #fff;
}
.kn-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 720px;
}
.kn-table caption {
  caption-side: top;
  text-align: left;
  padding: 20px 24px 4px;
  font: 700 12px/1.4 var(--font-body);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-400);
}
.kn-table th {
  background: var(--ink-50);
  text-align: left;
  padding: 13px 20px;
  font: 700 11px/1.3 var(--font-body);
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-500);
  border-bottom: 1px solid var(--ink-100);
  white-space: nowrap;
}
.kn-table td {
  padding: 14px 20px;
  font: 400 14px/1.55 var(--font-body);
  color: var(--ink-600);
  border-bottom: 1px solid var(--ink-50);
  vertical-align: top;
}
.kn-table tbody tr:last-child td { border-bottom: 0; }
.kn-table tbody tr:hover td { background: rgba(244, 246, 250, 0.7); }
.kn-table td:first-child { color: var(--ink-900); font-weight: 600; }
.kn-table .kn-num {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: -0.01em;
  color: var(--ink-900);
  white-space: nowrap;
}
.kn-table .kn-key { color: var(--accent-red); font-weight: 700; }
.kn-table .kn-tag {
  display: inline-block;
  padding: 3px 9px;
  border-radius: var(--r-pill);
  background: var(--ink-50);
  font: 600 11px/1.5 var(--font-body);
  color: var(--ink-600);
  white-space: nowrap;
}
.kn-table .kn-tag-red { background: rgba(230, 57, 70, 0.10); color: var(--accent-red-dark); }
.kn-table .kn-tag-amber { background: rgba(245, 158, 11, 0.14); color: #92610a; }
.kn-table .kn-tag-blue { background: rgba(29, 78, 216, 0.10); color: var(--accent-blue); }
.kn-table .kn-tag-green { background: rgba(16, 137, 90, 0.12); color: #0b6b46; }

.kn-note {
  display: flex;
  gap: 12px;
  margin-top: 18px;
  padding: 16px 20px;
  border-left: 3px solid var(--accent-red);
  background: var(--bg-tertiary);
  border-radius: 0 var(--r-md) var(--r-md) 0;
  font: 400 14px/1.65 var(--font-body);
  color: var(--ink-600);
}
.kn-note strong { color: var(--ink-900); font-weight: 700; }

/* ---------- STEPS ---------- */
.kn-steps { display: grid; gap: 0; counter-reset: knstep; }
.kn-step {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: 22px;
  padding: 26px 0;
  border-top: 1px solid var(--ink-100);
}
.kn-step:first-child { border-top: 0; padding-top: 6px; }
.kn-step-num {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  border: 1.5px solid var(--ink-200);
  display: flex;
  align-items: center;
  justify-content: center;
  font: 700 13px/1 var(--font-mono);
  color: var(--ink-900);
  background: #fff;
  transition: all var(--d-base) var(--ease-out);
}
.kn-step:hover .kn-step-num {
  background: var(--accent-red);
  border-color: var(--accent-red);
  color: #fff;
  transform: scale(1.06);
}
.kn-step-title {
  font: 700 16.5px/1.35 var(--font-display);
  letter-spacing: -0.012em;
  color: var(--ink-900);
  margin: 10px 0 8px;
}
.kn-step-text {
  font: 400 14.5px/1.72 var(--font-body);
  color: var(--ink-500);
  margin: 0;
  max-width: 82ch;
}
.kn-step-text strong { color: var(--ink-900); font-weight: 600; }
.kn-step-text code {
  font-family: var(--font-mono);
  font-size: 12.5px;
  background: var(--ink-50);
  padding: 2px 6px;
  border-radius: var(--r-sm);
  color: var(--accent-red-dark);
}

/* ---------- TOOLS ---------- */
.kn-tools {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}
.kn-tool {
  display: flex;
  flex-direction: column;
  background: #fff;
  border: 1px solid var(--ink-100);
  border-radius: var(--r-lg);
  overflow: hidden;
  text-decoration: none;
  transition: all var(--d-base) var(--ease-out);
}
.kn-tool:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}
.kn-tool-img {
  aspect-ratio: 4 / 3;
  background: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 14px;
  border-bottom: 1px solid var(--ink-50);
}
.kn-tool-img img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  transition: transform var(--d-slow) var(--ease-out);
}
.kn-tool:hover .kn-tool-img img { transform: scale(1.06); }
.kn-tool-body { padding: 16px 18px 18px; }
.kn-tool-name {
  font: 700 14.5px/1.35 var(--font-display);
  letter-spacing: -0.01em;
  color: var(--ink-900);
  margin: 0 0 6px;
}
.kn-tool-desc {
  font: 400 12.5px/1.55 var(--font-body);
  color: var(--ink-400);
  margin: 0;
}
.kn-tool-cta {
  margin-top: 12px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font: 600 11.5px/1 var(--font-body);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-red);
}

/* ---------- SAFETY ---------- */
.kn-safety {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 32px;
}
.kn-safety-item {
  display: flex;
  gap: 13px;
  align-items: flex-start;
  font: 400 14.5px/1.65 var(--font-body);
  color: var(--ink-600);
  padding: 14px 0;
  border-bottom: 1px solid var(--ink-100);
}
.kn-safety-item svg { flex: 0 0 auto; margin-top: 3px; color: var(--accent-red); }
.kn-safety-item strong { color: var(--ink-900); font-weight: 700; }

/* ---------- FAQ (native details) ---------- */
.kn-faq { border-top: 1px solid var(--ink-100); }
.kn-faq-item { border-bottom: 1px solid var(--ink-100); }
.kn-faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 22px 4px;
  cursor: pointer;
  list-style: none;
  font: 600 16.5px/1.4 var(--font-display);
  letter-spacing: -0.012em;
  color: var(--ink-900);
  transition: color var(--d-fast) var(--ease-out);
}
.kn-faq-item summary::-webkit-details-marker { display: none; }
.kn-faq-item summary:hover { color: var(--accent-red); }
.kn-faq-item summary::after {
  content: "";
  flex: 0 0 auto;
  width: 11px;
  height: 11px;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: rotate(45deg) translate(-2px, -2px);
  transition: transform var(--d-base) var(--ease-out);
}
.kn-faq-item[open] summary::after { transform: rotate(-135deg) translate(-4px, -2px); }
.kn-faq-body {
  font: 400 14.5px/1.75 var(--font-body);
  color: var(--ink-500);
  padding: 0 40px 24px 4px;
  max-width: 88ch;
}
.kn-faq-body strong { color: var(--ink-900); font-weight: 600; }

/* ---------- RELATED ---------- */
.kn-related {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}
.kn-related a {
  display: block;
  padding: 20px 22px;
  border: 1px solid var(--ink-100);
  border-radius: var(--r-md);
  background: #fff;
  text-decoration: none;
  transition: all var(--d-base) var(--ease-out);
}
.kn-related a:hover {
  border-color: var(--ink-900);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.kn-related-num {
  font: 700 11px/1 var(--font-mono);
  letter-spacing: 0.1em;
  color: var(--accent-red);
  display: block;
  margin-bottom: 10px;
}
.kn-related-name {
  font: 700 14.5px/1.35 var(--font-display);
  color: var(--ink-900);
}

/* ---------- CTA ---------- */
.kn-cta {
  background: var(--ink-900);
  color: #fff;
  padding: 68px 0;
  position: relative;
  overflow: hidden;
}
.kn-cta::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.035) 1px, transparent 1px);
  background-size: 56px 56px;
  -webkit-mask-image: radial-gradient(80% 100% at 80% 100%, #000 0%, transparent 70%);
  mask-image: radial-gradient(80% 100% at 80% 100%, #000 0%, transparent 70%);
}
.kn-cta-inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
  flex-wrap: wrap;
}
.kn-cta-title {
  font: 800 clamp(24px, 2.8vw, 36px) / 1.12 var(--font-display);
  letter-spacing: -0.03em;
  margin: 0 0 12px;
  max-width: 22ch;
}
.kn-cta-title em { font-style: normal; color: var(--accent-red-light); }
.kn-cta-desc {
  font: 400 16px/1.65 var(--font-body);
  color: rgba(255, 255, 255, 0.66);
  margin: 0;
  max-width: 56ch;
}
.kn-cta-actions { display: flex; gap: 12px; flex-wrap: wrap; }

/* ---------- OVERVIEW PAGE ---------- */
.kn-cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px;
}
.kn-card {
  display: flex;
  flex-direction: column;
  background: #fff;
  border: 1px solid var(--ink-100);
  border-radius: var(--r-xl);
  overflow: hidden;
  text-decoration: none;
  transition: all var(--d-base) var(--ease-out);
}
.kn-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-xl);
  border-color: transparent;
}
.kn-card-media {
  position: relative;
  aspect-ratio: 16 / 9;
  background: var(--ink-900);
  overflow: hidden;
}
.kn-card-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform var(--d-slow) var(--ease-out);
}
.kn-card:hover .kn-card-media img { transform: scale(1.05); }
.kn-card-body { padding: 26px 28px; display: flex; flex-direction: column; }
.kn-card-num {
  font: 700 11px/1 var(--font-mono);
  letter-spacing: 0.12em;
  color: var(--accent-red);
  margin-bottom: 12px;
}
.kn-card-title {
  font: 800 21px/1.2 var(--font-display);
  letter-spacing: -0.022em;
  color: var(--ink-900);
  margin: 0 0 10px;
}
.kn-card-desc {
  font: 400 14px/1.65 var(--font-body);
  color: var(--ink-500);
  margin: 0 0 16px;
  flex: 1 1 auto;
}
.kn-card-chips { display: flex; flex-wrap: wrap; gap: 7px; }
.kn-card-chip {
  font: 600 11px/1.5 var(--font-body);
  padding: 4px 10px;
  border-radius: var(--r-pill);
  background: var(--ink-50);
  color: var(--ink-500);
}
.kn-card-go {
  margin-top: 18px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font: 600 11.5px/1 var(--font-body);
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-900);
}
.kn-card:hover .kn-card-go { color: var(--accent-red); }

/* 知识库引导条 */
.kn-howto {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}
.kn-howto-item {
  padding: 24px 24px 26px;
  border: 1px solid var(--ink-100);
  border-radius: var(--r-lg);
  background: #fff;
}
.kn-howto-step {
  font: 700 11px/1 var(--font-mono);
  letter-spacing: 0.12em;
  color: var(--accent-red);
  margin-bottom: 14px;
  display: block;
}
.kn-howto-title {
  font: 700 16px/1.35 var(--font-display);
  color: var(--ink-900);
  margin: 0 0 8px;
}
.kn-howto-text { font: 400 14px/1.65 var(--font-body); color: var(--ink-500); margin: 0; }

/* ---------- RESPONSIVE ---------- */
@media (max-width: 1180px) {
  .kn-tools { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .kn-related { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .kn-cards { grid-template-columns: 1fr; }
}
@media (max-width: 1024px) {
  .kn-page { --kn-anchor: 138px; }
  .kn-hero { padding-top: 52px; }
  .kn-hero-grid { grid-template-columns: 1fr; gap: 36px; padding-bottom: 44px; }
  .kn-hero-num { font-size: 96px; top: 6px; }
  .kn-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .kn-stat:nth-child(2) { border-right: 0; }
  .kn-stat:nth-child(-n + 2) { border-bottom: 1px solid rgba(255, 255, 255, 0.10); }
  .kn-section { padding: 58px 0; }
  .kn-quick { grid-template-columns: 1fr; }
  .kn-safety { grid-template-columns: 1fr; }
  .kn-howto { grid-template-columns: 1fr; }
  .kn-tools { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .kn-rail { top: 68px; }
  .kn-rail-inner { height: 56px; }
  .kn-rail-label { display: none; }
}
@media (max-width: 767px) {
  .kn-page { --kn-anchor: 126px; }
  .kn-hero-title { max-width: none; }
  .kn-hero-sub { font-size: 15.5px; }
  .kn-stat { padding: 18px 18px 22px; }
  .kn-stat-num { font-size: 18px; }
  .kn-stats { grid-template-columns: 1fr 1fr; }
  .kn-section { padding: 46px 0; }
  .kn-step { grid-template-columns: 40px minmax(0, 1fr); gap: 16px; }
  .kn-step-num { width: 34px; height: 34px; font-size: 12px; }
  .kn-tools, .kn-related { grid-template-columns: 1fr 1fr; }
  .kn-card { grid-template-columns: 1fr; }
  .kn-card-media { aspect-ratio: 16 / 9; }
  .kn-card-body { padding: 22px 22px 24px; }
  .kn-faq-body { padding-right: 4px; }
  .kn-cta { padding: 52px 0; }
}
@media (max-width: 560px) {
  .kn-related { grid-template-columns: 1fr; }
  .kn-stats { grid-template-columns: 1fr; }
  .kn-stat { border-right: 0; border-bottom: 1px solid rgba(255, 255, 255, 0.10); }
  .kn-stat:last-child { border-bottom: 0; }
}
@media (prefers-reduced-motion: reduce) {
  .kn-page * { transition: none !important; }
}