@font-face {
  font-family: "Gowun Dodum";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("fonts/GowunDodum-Regular.woff2") format("woff2");
}

@font-face {
  font-family: "Source Code Pro";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("fonts/source-code-pro-400.woff2") format("woff2");
}

:root {
  --bg: #f4f6f8;
  --surface: #ffffff;
  --ink: #1a2332;
  --muted: #4a5568;
  --line: #d5dce6;
  --accent: #c45c26;
  --accent-ink: #9a3f12;
  --accent-soft: #fff3ea;
  --warn-bg: #fff1eb;
  --warn-ink: #8a2e0c;
  --note-bg: #eef3f8;
  --note-ink: #1e3a5f;
  --code-bg: #eef1f5;
  --shadow: none;
  --radius: 10px;
  --nav-h: 64px;
  --font: "Gowun Dodum", "Apple SD Gothic Neo", "Noto Sans KR", sans-serif;
  --mono: "Source Code Pro", ui-monospace, Menlo, Consolas, monospace;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 1rem);
}

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

  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }
}

body {
  margin: 0;
  min-height: 100dvh;
  color: var(--ink);
  background: var(--bg);
  font-family: var(--font);
  font-size: 1.05rem;
  font-weight: 400;
  font-synthesis: none;
  line-height: 1.7;
  word-break: keep-all;
  overflow-wrap: break-word;
  line-break: strict;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection {
  background: rgba(196, 92, 38, 0.22);
  color: var(--ink);
}

a {
  color: var(--accent-ink);
  text-underline-offset: 0.18em;
}

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

a:focus-visible,
button:focus-visible,
.toc a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

code,
pre {
  font-family: var(--mono);
  font-size: 0.9em;
  word-break: break-all;
  overflow-wrap: anywhere;
  line-break: auto;
}

code {
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.1em 0.35em;
}

pre {
  overflow-x: auto;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  line-height: 1.5;
}

pre code {
  background: none;
  border: 0;
  padding: 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  border-bottom: 1px solid var(--line);
  background: rgba(244, 246, 248, 0.92);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.site-header__inner {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 0.55rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 400;
  letter-spacing: -0.03em;
  font-size: 1.15rem;
}

.brand span {
  color: var(--muted);
  font-weight: 400;
  font-size: 0.85rem;
  letter-spacing: 0;
}

.nav {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  flex-wrap: nowrap;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 400;
  font-size: 0.92rem;
  padding: 0.45rem 0.7rem;
  border-radius: 8px;
  white-space: nowrap;
}

.nav a:hover {
  color: var(--ink);
  background: rgba(26, 35, 50, 0.05);
}

.nav a[aria-current="page"] {
  color: var(--accent-ink);
  background: var(--accent-soft);
}

.nav a.nav-external {
  color: var(--ink);
  border: 1px solid var(--line);
  background: var(--surface);
}

.nav a.nav-external:hover {
  border-color: var(--accent);
}

.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;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  margin-left: 0.25rem;
}

.lang-switch select {
  appearance: none;
  -webkit-appearance: none;
  min-height: 2.2rem;
  padding: 0.35rem 1.75rem 0.35rem 0.65rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background-color: var(--surface);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath fill='%235a6577' d='M1 1l5 5 5-5'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.55rem center;
  color: var(--ink);
  font: inherit;
  font-size: 0.88rem;
  cursor: pointer;
}

.lang-switch select:hover,
.lang-switch select:focus-visible {
  border-color: var(--accent);
}

.lang-switch select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.layout {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.75rem 0 4rem;
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 2.5rem;
  align-items: start;
}

.layout--solo {
  grid-template-columns: minmax(0, 1fr);
}

.toc {
  position: sticky;
  top: calc(var(--nav-h) + 1rem);
  max-height: calc(100dvh - var(--nav-h) - 2rem);
  overflow: auto;
  padding: 0.25rem 0;
}

.toc h2 {
  margin: 0 0 0.75rem;
  font-size: 0.78rem;
  font-weight: 400;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
  border: 0;
}

.toc ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

.toc a {
  display: block;
  padding: 0.4rem 0.65rem;
  margin: 0.1rem 0;
  border-radius: 8px;
  color: var(--muted);
  text-decoration: none;
  font-size: 0.92rem;
  line-height: 1.35;
  border-left: 2px solid transparent;
}

.toc a:hover {
  color: var(--ink);
  background: rgba(26, 35, 50, 0.04);
}

.toc a.is-active {
  color: var(--accent-ink);
  background: var(--accent-soft);
  border-left-color: var(--accent);
  font-weight: 400;
}

.content {
  min-width: 0;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
  gap: 1.75rem;
  align-items: center;
  margin-bottom: 1.75rem;
  padding-bottom: 1.75rem;
  border-bottom: 1px solid var(--line);
}

.hero__copy h1 {
  margin: 0 0 0.85rem;
  font-size: clamp(1.85rem, 3.2vw, 2.55rem);
  line-height: 1.15;
  letter-spacing: -0.035em;
  font-weight: 400;
  border: 0;
  color: var(--ink);
}

.hero__copy p {
  margin: 0 0 1rem;
  color: var(--muted);
  font-size: 1.05rem;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 0.35rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  min-height: 2.6rem;
  padding: 0.55rem 1rem;
  border-radius: 8px;
  border: 1px solid transparent;
  font: inherit;
  font-weight: 400;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease;
}

.btn:active {
  transform: translateY(1px);
}

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

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

.btn-secondary {
  background: var(--surface);
  color: var(--ink);
  border-color: var(--line);
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent-ink);
}

.hero__media {
  margin: 0;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.hero__media img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.hero__media figcaption {
  padding: 0.65rem 0.9rem;
  font-size: 0.85rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
  background: #fbfcfd;
}

.content > h2 {
  margin: 2.4rem 0 0.85rem;
  padding-top: 0.4rem;
  font-size: 1.45rem;
  letter-spacing: -0.02em;
  line-height: 1.25;
  border-bottom: 1px solid var(--line);
  padding-bottom: 0.45rem;
}

.content > h2:first-of-type {
  margin-top: 0.5rem;
}

.content p {
  margin: 0 0 1rem;
}

.content ul,
.content ol {
  margin: 0 0 1.15rem;
  padding-left: 1.25rem;
}

.content li {
  margin: 0.35rem 0;
}

.content li::marker {
  color: var(--accent);
}

.figure {
  margin: 1.25rem 0 1.5rem;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.figure img {
  width: 100%;
}

.figure-pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.85rem;
  margin: 1.25rem 0 1.5rem;
}

.figure-pair .figure {
  margin: 0;
}

.figure figcaption {
  padding: 0.65rem 0.9rem;
  font-size: 0.88rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
  background: #fbfcfd;
}

.callout {
  margin: 1.1rem 0 1.35rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--line);
}

.callout p {
  margin: 0;
}

.callout strong {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 0.85rem;
  letter-spacing: 0.02em;
}

.callout-warn {
  background: var(--warn-bg);
  border-color: rgba(196, 92, 38, 0.35);
  color: var(--warn-ink);
}

.callout-note {
  background: var(--note-bg);
  border-color: rgba(30, 58, 95, 0.2);
  color: var(--note-ink);
}

.table-wrap {
  margin: 1rem 0 1.75rem;
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 0.15rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

th,
td {
  padding: 0.7rem 0.85rem;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

th {
  background: #f0f3f7;
  font-weight: 400;
  color: var(--ink);
  white-space: nowrap;
}

.table-parts td:nth-child(3),
.table-parts th:nth-child(3) {
  text-align: right;
  font-variant-numeric: tabular-nums;
  font-family: var(--mono);
  font-size: 0.88em;
}

.hero--solo {
  grid-template-columns: 1fr;
}

tbody tr:last-child td {
  border-bottom: 0;
}

tbody tr:hover td {
  background: rgba(196, 92, 38, 0.04);
}

.page-intro {
  margin: 0 0 1rem;
  color: var(--muted);
}

.hero .page-intro {
  margin-bottom: 0;
}

.site-footer {
  border-top: 1px solid var(--line);
  background: #eef1f5;
  padding: 1.5rem 0 2rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.site-footer__inner {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.5rem;
  justify-content: space-between;
}

.site-footer a {
  color: var(--ink);
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .toc {
    position: static;
    max-height: none;
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.35rem;
    padding: 0.85rem;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
  }

  .toc ol {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.15rem;
  }

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

  .figure-pair {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  :root {
    --nav-h: 56px;
  }

  body {
    font-size: 1rem;
  }

  .site-header__inner {
    width: calc(100% - 1.25rem);
  }

  .brand span {
    display: none;
  }

  .nav a {
    padding: 0.4rem 0.5rem;
    font-size: 0.85rem;
  }

  .nav a.nav-external {
    display: none;
  }

  .lang-switch select {
    font-size: 0.8rem;
    padding-left: 0.45rem;
    padding-right: 1.5rem;
  }

  .layout {
    width: calc(100% - 1.25rem);
    padding-top: 1.1rem;
  }

  .toc ol {
    grid-template-columns: 1fr;
  }

  .hero__copy h1 {
    font-size: 1.7rem;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header {
    background: var(--bg);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12171f;
    --surface: #1a2230;
    --ink: #e8edf4;
    --muted: #a3aebf;
    --line: #2c3648;
    --accent: #e07a45;
    --accent-ink: #f0a078;
    --accent-soft: rgba(224, 122, 69, 0.14);
    --warn-bg: rgba(224, 122, 69, 0.12);
    --warn-ink: #f3c2a4;
    --note-bg: rgba(120, 160, 210, 0.12);
    --note-ink: #c5d7ef;
    --code-bg: #141b26;
    --shadow: none;
  }

  body {
    background: var(--bg);
  }

  .site-header {
    background: rgba(18, 23, 31, 0.92);
  }

  .hero__media figcaption,
  .figure figcaption,
  th {
    background: #151c28;
  }

  .site-footer {
    background: #0e131a;
  }

  .btn-primary {
    color: #1a120e;
  }

  .btn-primary:hover {
    color: #1a120e;
  }
}