:root {
  --bg: #111315;
  --surface: #1a1d20;
  --surface-2: #22262a;
  --line: #353b40;
  --text: #f7f7f5;
  --muted: #aeb4b8;
  --accent: #ff5a1f;
  --accent-2: #5fc49a;
  --max: 1120px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Pretendard, "Apple SD Gothic Neo", "Noto Sans KR", sans-serif;
  line-height: 1.75;
  word-break: keep-all;
  overflow-wrap: break-word;
}

a { color: inherit; }
img { max-width: 100%; }

.kb-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--line);
  background: rgba(17, 19, 21, .96);
  backdrop-filter: blur(10px);
}

.kb-nav__inner {
  width: min(var(--max), calc(100% - 32px));
  height: 62px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
}

.kb-brand {
  color: #fff;
  font-size: 17px;
  font-weight: 900;
  text-decoration: none;
  white-space: nowrap;
}

.kb-brand span { color: var(--accent); }

.kb-nav__links {
  display: flex;
  align-items: center;
  gap: 20px;
  color: #d4d7d9;
  font-size: 13px;
}

.kb-nav__links a { text-decoration: none; }
.kb-nav__links a:hover,
.kb-nav__links a:focus-visible { color: #fff; }

.kb-phone {
  padding: 8px 12px;
  border-radius: 6px;
  background: var(--accent);
  color: #fff !important;
  font-weight: 800;
}

.kb-hero {
  min-height: 460px;
  padding: 88px 20px 72px;
  border-bottom: 1px solid var(--line);
  background:
    linear-gradient(90deg, rgba(11, 12, 13, .96) 0%, rgba(11, 12, 13, .84) 42%, rgba(11, 12, 13, .38) 100%),
    url("battery-knowledge-master.png") center / cover no-repeat;
  display: flex;
  align-items: center;
}

.kb-hero__inner {
  width: min(var(--max), 100%);
  margin: 0 auto;
}

.kb-eyebrow {
  margin: 0 0 14px;
  color: var(--accent-2);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: .08em;
}

.kb-hero h1 {
  max-width: 700px;
  margin: 0;
  font-size: clamp(38px, 7vw, 68px);
  line-height: 1.12;
  letter-spacing: 0;
}

.kb-hero h1 span { color: var(--accent); }

.kb-hero p:last-child {
  max-width: 650px;
  margin: 22px 0 0;
  color: #d3d6d8;
  font-size: 17px;
}

.kb-hero__inner > p:not(.kb-eyebrow) {
  max-width: 650px;
  margin: 22px 0 0;
  color: #d3d6d8;
  font-size: 17px;
}

.kb-hero__stats {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 28px;
}

.kb-hero__stats span,
.kb-hero__stats a {
  padding: 9px 12px;
  border: 1px solid #4a4f53;
  border-radius: 6px;
  background: rgba(14, 16, 17, .78);
  color: #e4e7e9;
  font-size: 13px;
  text-decoration: none;
}

.kb-hero__stats strong { color: var(--accent-2); }

.kb-section {
  width: min(var(--max), calc(100% - 32px));
  margin: 0 auto;
  padding: 64px 0;
}

.kb-section--light {
  width: 100%;
  padding-inline: max(16px, calc((100% - var(--max)) / 2));
  border-top: 1px solid var(--line);
  background: #111314;
}

.kb-section__head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 28px;
}

.kb-section__head h2 { margin: 0; font-size: 30px; }
.kb-section__head > p { margin: 0; color: var(--muted); font-size: 13px; }

.kb-category-hero {
  padding: 72px 16px 54px;
  border-bottom: 1px solid var(--line);
  background: #111314;
}

.kb-category-hero > div { width: min(var(--max), 100%); margin: 0 auto; }
.kb-category-hero h1 { margin: 8px 0 12px; font-size: 44px; letter-spacing: 0; }
.kb-category-hero p:last-child { margin: 0; color: var(--muted); }

.kb-main,
.kb-article-wrap {
  width: min(var(--max), calc(100% - 32px));
  margin: 0 auto;
  padding: 64px 0 100px;
}

.kb-breadcrumb {
  margin: 0 0 30px;
  color: #92989c;
  font-size: 13px;
}

.kb-breadcrumb a { text-decoration: none; }
.kb-breadcrumb a:hover { color: var(--accent); }
.kb-breadcrumb span { margin: 0 8px; }

.kb-section-head {
  margin-bottom: 26px;
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
}

.kb-section-head h2 {
  margin: 0;
  font-size: 30px;
  line-height: 1.3;
}

.kb-section-head p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

.kb-cluster-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 72px;
}

.kb-cluster-card {
  min-height: 148px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  display: flex;
  flex-direction: column;
  text-decoration: none;
  transition: border-color .2s ease, transform .2s ease;
}

.kb-cluster-card:hover,
.kb-cluster-card:focus-visible {
  border-color: var(--accent);
  transform: translateY(-2px);
  outline: none;
}

.kb-cluster-card span { color: var(--accent-2); font-size: 12px; font-weight: 800; }
.kb-cluster-card strong { margin-top: 16px; font-size: 18px; }
.kb-cluster-card small { margin-top: auto; padding-top: 12px; color: var(--muted); }

.kb-cluster {
  min-height: 170px;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  text-decoration: none;
  transition: border-color .2s ease, transform .2s ease;
}

.kb-cluster:hover,
.kb-cluster:focus-visible {
  border-color: var(--accent);
  transform: translateY(-2px);
  outline: none;
}

.kb-cluster__number {
  color: var(--accent-2);
  font-size: 12px;
  font-weight: 900;
}

.kb-cluster h3 {
  margin: 18px 0 8px;
  font-size: 20px;
  line-height: 1.4;
}

.kb-cluster p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

.kb-post-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.kb-post-card {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.kb-post-card > a { display: block; height: 100%; text-decoration: none; }
.kb-post-card img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  transition: transform .3s ease;
}
.kb-post-card:hover img { transform: scale(1.02); }
.kb-post-card__body { padding: 18px; }
.kb-post-card__body p { margin: 0; color: var(--accent-2); font-size: 11px; font-weight: 800; }
.kb-post-card__body h2 { margin: 10px 0 16px; font-size: 17px; line-height: 1.48; }
.kb-post-card__body time { color: var(--muted); font-size: 11px; }

.kb-post-card[hidden] { display: none; }

.kb-pagination {
  min-height: 44px;
  margin-top: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
}

.kb-pagination button {
  min-width: 40px;
  height: 40px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  color: var(--text);
  font: inherit;
  font-size: 13px;
  font-weight: 800;
  cursor: pointer;
}

.kb-pagination button:hover:not(:disabled),
.kb-pagination button:focus-visible {
  border-color: var(--accent);
  outline: none;
}

.kb-pagination button.is-active {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
}

.kb-pagination button:disabled {
  color: #747a7e;
  cursor: not-allowed;
}

.kb-card {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.kb-card__image {
  display: block;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: #24282b;
}

.kb-card img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform .35s ease;
}

.kb-card:hover img { transform: scale(1.02); }

.kb-card__body { padding: 18px; }

.kb-card__meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  color: #9ba1a5;
  font-size: 11px;
}

.kb-card__category { color: var(--accent-2); font-weight: 800; }

.kb-card h3 {
  margin: 12px 0 9px;
  font-size: 17px;
  line-height: 1.48;
}

.kb-card h3 a { text-decoration: none; }
.kb-card h3 a:hover { color: var(--accent); }

.kb-card p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.65;
}

.kb-empty {
  padding: 40px;
  border: 1px dashed #4a4f53;
  border-radius: 8px;
  color: var(--muted);
  text-align: center;
}

.kb-article-wrap { max-width: 860px; }

.kb-article-header { margin-bottom: 34px; }

.kb-article-header h1 {
  margin: 12px 0 18px;
  font-size: clamp(34px, 6vw, 54px);
  line-height: 1.22;
  letter-spacing: 0;
}

.kb-article-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  color: #9ea4a8;
  font-size: 13px;
}

.kb-publish-notice {
  margin: 22px 0;
  padding: 14px 16px;
  border-left: 3px solid #eab308;
  background: #292515;
  color: #f6e39a;
  font-size: 13px;
}

.kb-article-hero {
  width: 100%;
  height: auto;
  margin: 0 0 34px;
  border: 1px solid var(--line);
  border-radius: 8px;
  display: block;
}

.kb-answer {
  margin: 0 0 26px;
  padding: 22px;
  border-left: 4px solid var(--accent);
  background: #1c1f21;
  color: #e7e8e8;
  font-size: 17px;
}

.kb-summary {
  margin: 0 0 42px;
  padding: 22px;
  border: 1px solid #3e554b;
  border-radius: 8px;
  background: #18251f;
}

.kb-summary strong { color: #8de0ba; }
.kb-summary ol { margin: 12px 0 0; padding-left: 22px; }

.kb-article h2 {
  margin: 56px 0 16px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 28px;
  line-height: 1.38;
}

.kb-article h3 {
  margin: 30px 0 10px;
  font-size: 20px;
  line-height: 1.45;
}

.kb-article p { color: #d3d6d7; }
.kb-article strong { color: #fff; }

.kb-article table {
  width: 100%;
  margin: 24px 0;
  border-collapse: collapse;
  background: var(--surface);
  font-size: 14px;
}

.kb-article th,
.kb-article td {
  padding: 13px 14px;
  border: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.kb-article th { background: #252a2e; color: #fff; }
.kb-article td { color: #c7cbcd; }

.kb-checklist,
.kb-steps {
  padding: 22px 22px 22px 42px;
  border-radius: 8px;
  background: var(--surface);
}

.kb-checklist li,
.kb-steps li { margin: 8px 0; color: #d1d4d6; }

.kb-faq details {
  border-bottom: 1px solid var(--line);
  padding: 18px 0;
}

.kb-faq summary {
  cursor: pointer;
  color: #fff;
  font-weight: 800;
}

.kb-faq details p { margin: 12px 0 0; }

.kb-sources {
  margin-top: 54px;
  padding: 22px;
  border-radius: 8px;
  background: #17191b;
}

.kb-sources h2 { margin-top: 0; border-top: 0; padding-top: 0; }
.kb-sources li { margin: 10px 0; color: #bac0c3; font-size: 13px; }
.kb-sources a { color: #9ed9c0; }

.kb-related {
  margin-top: 40px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.kb-related a {
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  text-decoration: none;
  font-size: 13px;
}

.kb-related a:hover { border-color: var(--accent); }

.kb-footer {
  padding: 38px 20px 110px;
  border-top: 1px solid var(--line);
  background: #0d0f10;
  color: #969ca0;
  text-align: center;
  font-size: 12px;
}

.kb-footer a { color: #d4d6d7; }

@media (max-width: 900px) {
  .kb-cluster-grid,
  .kb-post-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .kb-nav__links a:not(.kb-phone) { display: none; }
}

@media (max-width: 620px) {
  .kb-nav__inner { width: min(100% - 24px, var(--max)); }
  .kb-brand { font-size: 15px; }
  .kb-phone { font-size: 12px; padding: 7px 9px; }
  .kb-hero { min-height: 400px; padding: 72px 16px 58px; background-position: 63% center; }
  .kb-hero h1 { font-size: 40px; }
  .kb-hero p:last-child { font-size: 15px; }
  .kb-hero__inner > p:not(.kb-eyebrow) { font-size: 15px; }
  .kb-main,
  .kb-article-wrap { width: min(100% - 24px, var(--max)); padding-top: 44px; }
  .kb-cluster-grid,
  .kb-post-grid,
  .kb-related { grid-template-columns: 1fr; }
  .kb-section-head { align-items: start; flex-direction: column; }
  .kb-section__head { align-items: start; flex-direction: column; }
  .kb-category-hero h1 { font-size: 34px; }
  .kb-article-header h1 { font-size: 34px; }
  .kb-article h2 { font-size: 24px; }
  .kb-article table { display: block; overflow-x: auto; white-space: normal; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; }
}