@font-face {
  font-family: "Pretendard";
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
  src: local("Pretendard Variable"),
       url("./fonts/PretendardVariable.woff2") format("woff2-variations");
}

:root {
  color-scheme: dark;
  --bg: #0b0e15;
  --bg-2: #10141f;
  --surface: #131824;
  --surface-2: #171d2c;
  --border: rgba(255, 255, 255, 0.1);
  --border-soft: rgba(255, 255, 255, 0.06);
  --text: #eef1f8;
  --text-dim: #aab3c6;
  --text-faint: #858fa4;
  --accent: #3ddbb4;
  --accent-deep: #14b98c;
  --accent-soft: rgba(61, 219, 180, 0.1);
  --link: #9db1ff;
  --warn: #ffc078;
  --warn-soft: rgba(255, 192, 120, 0.09);
  --font: "Pretendard", system-ui, -apple-system, "Segoe UI", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
}

html[data-theme="light"] {
  color-scheme: light;
  --bg: #f5f7fb;
  --bg-2: #edf2f8;
  --surface: #ffffff;
  --surface-2: #f3f6fa;
  --border: rgba(29, 44, 67, 0.15);
  --border-soft: rgba(29, 44, 67, 0.08);
  --text: #172033;
  --text-dim: #4f5d73;
  --text-faint: #69758a;
  --accent: #087f66;
  --accent-deep: #056b56;
  --accent-soft: rgba(8, 127, 102, 0.08);
  --link: #365bb4;
  --warn: #9a5f17;
  --warn-soft: rgba(154, 95, 23, 0.08);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(1050px 600px at 82% -8%, rgba(61, 219, 180, 0.14), transparent 62%),
    radial-gradient(900px 520px at -8% 8%, rgba(107, 138, 253, 0.13), transparent 62%),
    linear-gradient(180deg, var(--bg-2), var(--bg) 34rem);
  font-family: var(--font);
  line-height: 1.5;
  letter-spacing: -0.01em;
  -webkit-font-smoothing: antialiased;
}

body::before {
  position: fixed;
  z-index: -1;
  inset: 0;
  background-image:
    linear-gradient(rgba(154, 183, 255, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(154, 183, 255, 0.04) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: linear-gradient(#000, transparent 42rem);
  content: "";
  pointer-events: none;
}

body[data-i18n-loading] [data-i18n],
body[data-i18n-loading] [data-i18n-html] {
  visibility: hidden;
}

a { color: inherit; }

.principles-topbar {
  position: sticky;
  z-index: 50;
  top: 0;
  border-bottom: 1px solid var(--border-soft);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  -webkit-backdrop-filter: blur(16px) saturate(1.3);
  backdrop-filter: blur(16px) saturate(1.3);
}

.principles-topbar__inner {
  display: flex;
  width: min(calc(100% - 2rem), 70rem);
  min-height: 3.75rem;
  margin-inline: auto;
  align-items: center;
  gap: 1rem;
}

.principles-back {
  display: inline-flex;
  min-height: 2.75rem;
  align-items: center;
  gap: 0.55rem;
  color: var(--text-dim);
  font-size: 0.875rem;
  font-weight: 700;
  text-decoration: none;
}

.principles-back:hover { color: var(--text); }

.principles-wordmark {
  margin-right: auto;
  color: var(--text-faint);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.lang-toggle {
  display: flex;
  padding: 0.2rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
}

.lang-toggle button,
.theme-toggle {
  border: 0;
  color: var(--text-dim);
  background: transparent;
  font: 800 0.72rem/1 var(--font);
  cursor: pointer;
}

.lang-toggle button {
  min-width: 2.25rem;
  min-height: 2rem;
  border-radius: 999px;
}

.lang-toggle button.active {
  color: var(--text);
  background: var(--surface-2);
}

.theme-toggle {
  display: grid;
  width: 2.4rem;
  height: 2.4rem;
  border: 1px solid var(--border);
  border-radius: 50%;
  place-items: center;
  font-size: 1rem;
}

:where(.principles-back, .lang-toggle button, .theme-toggle, .principles-toc a, .source-list a):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.principles-page {
  padding-block: clamp(3.5rem, 8vw, 6.5rem) 5rem;
}

.principles-hero {
  padding-bottom: clamp(2.5rem, 5vw, 4rem);
  border-bottom: 1px solid var(--border);
}

.principles-kicker {
  display: flex;
  margin: 0 0 1rem;
  align-items: center;
  gap: 0.65rem;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.principles-kicker::before {
  width: 1.75rem;
  height: 1px;
  background: var(--accent);
  content: "";
}

.principles-hero h1 {
  max-width: 13em;
  margin: 0 0 1.25rem;
  font-size: clamp(2.25rem, 5vw, 4.35rem);
  line-height: 1.06;
  letter-spacing: -0.045em;
}

.principles-hero .content-lead { color: var(--text-dim); }

.principles-meta {
  display: flex;
  margin: 1.5rem 0 0;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  color: var(--text-faint);
  font-size: 0.84rem;
}

.principles-intro {
  margin-block: 2rem clamp(2.5rem, 5vw, 4rem);
  padding: 0.1rem 0 0.1rem 1.1rem;
  border-left: 2px solid var(--accent);
  color: var(--text-dim);
  font-size: 1rem;
  line-height: 1.78;
}

.principles-intro strong { color: var(--text); }

.principles-toc {
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

.principles-toc__title {
  display: block;
  margin-bottom: 0.75rem;
  color: var(--text-faint);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.principles-toc ol {
  display: grid;
  margin: 0;
  padding: 0;
  gap: 0.2rem;
  list-style: none;
}

.principles-toc a {
  display: grid;
  min-height: 2.4rem;
  padding: 0.5rem 0;
  grid-template-columns: 2rem minmax(0, 1fr);
  align-items: center;
  color: var(--text-dim);
  font-size: 0.88rem;
  font-weight: 700;
  line-height: 1.35;
  text-decoration: none;
}

.principles-toc a span {
  color: var(--text-faint);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
}

.principles-toc a:hover,
.principles-toc a.is-current {
  color: var(--text);
}

.principles-toc a:hover { text-decoration: underline; text-underline-offset: 0.22em; }
.principles-toc a.is-current { color: var(--accent); }
.principles-toc a.is-current span { color: currentColor; }

.principle-section {
  scroll-margin-top: 5.5rem;
  margin-top: 0;
  padding-block: clamp(3rem, 6vw, 5rem);
  border-top: 1px solid var(--border);
}

.principle-section:first-child { border-top: 0; }

.principle-section .content-section__header {
  align-items: baseline;
  gap: 0.85rem;
}

.section-number {
  flex: 0 0 auto;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 850;
  letter-spacing: 0.09em;
}

.principle-section h2 {
  font-size: clamp(1.55rem, 3vw, 2.15rem);
  line-height: 1.25;
  letter-spacing: -0.025em;
}

.principle-answer {
  margin: 0 0 1.35rem;
  color: var(--text);
  font-size: clamp(1.08rem, 1rem + 0.35vw, 1.28rem);
  font-weight: 760;
  line-height: 1.62;
}

.principle-section p { color: var(--text-dim); }

.principle-section > h3 {
  margin: 2.5rem 0 0.75rem;
  color: var(--text);
  font-size: 1.15rem;
  line-height: 1.45;
  letter-spacing: -0.015em;
}

.practice-rule {
  margin-block: 1.75rem;
  padding: 0;
}

.practice-rule__label {
  display: block;
  margin: 0 0 0.45rem;
  color: var(--text);
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.5;
}

.practice-rule p {
  margin: 0;
  color: var(--text-dim);
  font-size: 1rem;
  line-height: 1.78;
}

.principle-caution {
  margin-block: 1.75rem;
  padding: 0.05rem 0 0.05rem 1rem;
  border-left: 2px solid var(--warn);
  color: var(--text-dim);
  font-size: 1rem;
  line-height: 1.78;
}

.principle-caution strong { color: var(--warn); }

.principle-matrix {
  width: 100%;
  margin-block: 1.75rem;
  border-collapse: collapse;
  font-size: 0.94rem;
}

.principle-matrix th,
.principle-matrix td {
  padding: 0.9rem 0.85rem;
  border-bottom: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}

.principle-matrix th {
  color: var(--text-faint);
  font-size: 0.75rem;
  font-weight: 850;
  letter-spacing: 0.05em;
}

.principle-matrix td { color: var(--text-dim); }
.principle-matrix td:first-child { color: var(--text); font-weight: 750; }

.source-block {
  margin-top: 2rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--border);
}

.source-block h3 {
  margin: 0 0 0.85rem;
  color: var(--text-faint);
  font-size: 0.76rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.source-list {
  display: grid;
  margin: 0;
  padding: 0;
  gap: 0.85rem;
  list-style: none;
}

.source-list li {
  color: var(--text-faint);
  font-size: 0.84rem;
  line-height: 1.58;
}

.source-list a {
  color: var(--link);
  font-weight: 720;
  text-decoration-line: underline;
  text-decoration-color: color-mix(in srgb, var(--link) 40%, transparent);
  text-underline-offset: 0.2em;
}

.source-list a:hover { text-decoration-color: var(--link); }

.principles-method {
  margin-top: 1rem;
  padding-block: clamp(3rem, 6vw, 4.5rem);
  border-top: 1px solid var(--border);
}

.principles-method h2 {
  margin: 0 0 1rem;
  font-size: clamp(1.35rem, 2.5vw, 1.8rem);
}

.principles-method p {
  margin: 0 0 1em;
  color: var(--text-dim);
}

.principles-footer {
  padding-block: 2rem 3rem;
  border-top: 1px solid var(--border);
  color: var(--text-faint);
  font-size: 0.8rem;
}

@media (max-width: 62.5rem) {
  .principles-intro { margin-bottom: 1.5rem; }

  .principles-toc {
    margin-bottom: 1rem;
  }

  .principles-toc ol {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 48rem) {
  .principles-wordmark { display: none; }
  .principles-back { margin-right: auto; }
  .principles-page { padding-top: 2.75rem; }
  .principles-hero h1 { font-size: clamp(2.15rem, 11vw, 3.1rem); }
  .principles-toc ol { grid-template-columns: 1fr; }

  .principle-section .content-section__header {
    flex-direction: row;
    gap: 0.7rem;
  }

  .principle-matrix,
  .principle-matrix tbody,
  .principle-matrix tr,
  .principle-matrix td {
    display: block;
    width: 100%;
  }

  .principle-matrix thead { display: none; }

  .principle-matrix tr {
    padding-block: 0.9rem;
    border-bottom: 1px solid var(--border);
  }

  .principle-matrix td {
    display: grid;
    padding: 0.25rem 0;
    border: 0;
    grid-template-columns: 5.5rem minmax(0, 1fr);
    gap: 0.75rem;
  }

  .principle-matrix td::before {
    color: var(--text-faint);
    content: attr(data-label-ko);
    font-size: 0.75rem;
    font-weight: 800;
  }

  html:lang(en) .principle-matrix td::before {
    content: attr(data-label-en);
  }
}

@media (max-width: 24rem) {
  .principles-topbar__inner { width: min(calc(100% - 1rem), 70rem); gap: 0.45rem; }
  .principles-back { font-size: 0.8rem; }
  .principles-meta { display: grid; }
  .principle-section .content-section__header { align-items: flex-start; }
  .principle-section h2 { font-size: 1.45rem; }
}

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

@media (forced-colors: active) {
  .theme-toggle,
  .lang-toggle { border-color: CanvasText; }
}