:root {
  color-scheme: light dark;
  --font-heading: "Space Grotesk", "Trebuchet MS", "Segoe UI", sans-serif;
  --font-body: "Source Sans 3", "Segoe UI", "Tahoma", sans-serif;
  --radius-sm: 12px;
  --radius-md: 18px;
  --radius-lg: 28px;
  --shadow-sm: 0 10px 26px -18px rgba(4, 28, 56, 0.5);
  --shadow-md: 0 24px 70px -40px rgba(2, 16, 41, 0.55);
  --bg: #f3f8ff;
  --bg-accent: radial-gradient(circle at 15% 20%, rgba(81, 161, 255, 0.22), transparent 38%),
    radial-gradient(circle at 85% 2%, rgba(35, 190, 198, 0.22), transparent 34%),
    linear-gradient(165deg, #f9fcff 0%, #e8f3ff 52%, #f6fbff 100%);
  --surface: #ffffff;
  --surface-alt: #edf5ff;
  --surface-soft: #f8fbff;
  --text: #17263d;
  --text-soft: #4a5f7d;
  --accent: #1975d2;
  --accent-strong: #0f57a3;
  --border: #cddcf0;
  --success: #146a4f;
  --danger: #a33040;
  --ring: rgba(25, 117, 210, 0.28);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0b1522;
  --bg-accent: radial-gradient(circle at 10% 15%, rgba(67, 133, 197, 0.28), transparent 34%),
    radial-gradient(circle at 95% 2%, rgba(40, 172, 165, 0.22), transparent 30%),
    linear-gradient(165deg, #09121f 0%, #0c1c30 48%, #091727 100%);
  --surface: #122438;
  --surface-alt: #1a3049;
  --surface-soft: #182d45;
  --text: #ecf4ff;
  --text-soft: #b4c6de;
  --accent: #66b4ff;
  --accent-strong: #91cbff;
  --border: #2f4c69;
  --success: #7ad8b7;
  --danger: #ff9ca8;
  --ring: rgba(102, 180, 255, 0.34);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: var(--font-body);
  background: var(--bg-accent);
  color: var(--text);
  line-height: 1.6;
}

img,
svg {
  max-width: 100%;
}

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

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

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--surface);
  color: var(--text);
  padding: 0.5rem 0.8rem;
  border-radius: var(--radius-sm);
  z-index: 999;
}

.skip-link:focus-visible {
  left: 1rem;
  top: 1rem;
}

.site-shell {
  width: min(1120px, calc(100% - 2.2rem));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(10px);
  background: color-mix(in srgb, var(--surface) 80%, transparent);
  border-bottom: 1px solid color-mix(in srgb, var(--border) 75%, transparent);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  text-decoration: none;
  color: inherit;
  font-family: var(--font-heading);
  font-weight: 700;
}

.brand__logo {
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 50%;
  object-fit: cover;
  box-shadow: var(--shadow-sm);
}

.brand__badge {
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(145deg, var(--accent), #2ba2d4);
  color: #fff;
  font-size: 1rem;
  box-shadow: var(--shadow-sm);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
}

.site-nav a {
  text-decoration: none;
  font-weight: 600;
  color: var(--text-soft);
  font-size: 0.96rem;
  padding: 0.45rem 0.7rem;
  border-radius: 999px;
}

.site-nav a:hover,
.site-nav a:focus-visible,
.site-nav a[aria-current="page"] {
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 14%, transparent);
}

.nav-group {
  position: relative;
}

.nav-group__toggle {
  border: 0;
  background: transparent;
  color: var(--text-soft);
  font: inherit;
  font-weight: 600;
  padding: 0.45rem 0.7rem;
  border-radius: 999px;
  cursor: pointer;
}

.nav-group__toggle:hover,
.nav-group__toggle:focus-visible {
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 14%, transparent);
}

.nav-group__menu {
  position: absolute;
  top: calc(100% + 0.45rem);
  right: 0;
  display: none;
  min-width: 170px;
  padding: 0.35rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-md);
}

.nav-group.is-open .nav-group__menu {
  display: grid;
}

.nav-group__menu a {
  border-radius: 8px;
}

.nav-menu-toggle {
  display: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface-alt);
  color: var(--text);
  padding: 0.5rem 0.75rem;
  font-weight: 700;
  cursor: pointer;
}

.theme-toggle {
  width: 44px;
  height: 44px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface-alt);
  color: var(--text);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.theme-toggle:hover {
  transform: translateY(-1px);
  border-color: var(--accent);
}

.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  width: 20px;
  height: 20px;
}

:root[data-theme="light"] .theme-toggle .icon-moon,
:root[data-theme="dark"] .theme-toggle .icon-sun {
  display: none;
}

main {
  padding: 2.4rem 0 3rem;
}

.hero {
  background: linear-gradient(140deg, color-mix(in srgb, var(--surface) 88%, transparent), color-mix(in srgb, var(--surface-alt) 88%, transparent));
  border: 1px solid color-mix(in srgb, var(--border) 78%, transparent);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: clamp(1.2rem, 2.6vw, 2.2rem);
}

.hero h1 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: clamp(1.7rem, 2.8vw, 2.45rem);
  line-height: 1.2;
}

.hero p {
  margin: 0.75rem 0 0;
  color: var(--text-soft);
  max-width: 70ch;
}

.converter-grid {
  margin-top: 1.25rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
  box-shadow: var(--shadow-sm);
}

.card h2 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 1.25rem;
}

.card p {
  margin: 0.35rem 0 0.9rem;
  color: var(--text-soft);
}

.field {
  display: grid;
  gap: 0.45rem;
}

.field label {
  font-weight: 700;
}

.field input,
.field textarea {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-soft);
  color: var(--text);
  font: inherit;
  padding: 0.7rem 0.85rem;
}

.field input:focus-visible,
.field textarea:focus-visible,
button:focus-visible,
a:focus-visible {
  outline: 3px solid var(--ring);
  outline-offset: 2px;
}

.field small {
  color: var(--text-soft);
}

.card__actions {
  margin-top: 0.85rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
}

button {
  font: inherit;
}

.btn {
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 0.58rem 0.9rem;
  cursor: pointer;
  font-weight: 700;
  min-height: 44px;
}

.btn--primary {
  background: linear-gradient(140deg, var(--accent), #2aa4d0);
  color: #fff;
}

.btn--primary:hover {
  filter: brightness(1.08);
}

.btn--secondary {
  background: var(--surface-alt);
  color: var(--text);
  border-color: var(--border);
}

.result-box {
  margin-top: 0.85rem;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 0.72rem 0.85rem;
  background: var(--surface-soft);
}

.result-box strong {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 0.92rem;
}

.result-value {
  font-family: var(--font-heading);
  font-size: clamp(1.2rem, 2.6vw, 1.6rem);
  letter-spacing: 0.03em;
  word-break: break-word;
}

.roman-overline-svg {
  display: inline-block;
  vertical-align: -0.18em;
  overflow: visible;
}

.roman-overline-svg text {
  fill: currentColor;
  font-family: var(--font-heading);
  font-size: 28px;
  font-weight: 700;
}

.roman-overline-svg line {
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
}

.status,
.form-status {
  margin-top: 0.5rem;
  font-size: 0.92rem;
  color: var(--text-soft);
}

.status[data-state="error"],
.form-status[data-state="error"] {
  color: var(--danger);
}

.status[data-state="success"],
.form-status[data-state="success"] {
  color: var(--success);
}

.content-grid {
  margin-top: 1.2rem;
  display: grid;
  gap: 1rem;
  grid-template-columns: 1fr;
}

.content-card {
  background: color-mix(in srgb, var(--surface) 94%, transparent);
  border: 1px solid color-mix(in srgb, var(--border) 76%, transparent);
  border-radius: var(--radius-md);
  padding: 1rem;
}

.content-card h2,
.content-card h3 {
  margin-top: 0;
  font-family: var(--font-heading);
}

.blog-card__eyebrow {
  margin: 0 0 0.45rem;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.blog-card h2 {
  margin-bottom: 0.45rem;
}

.blog-card h2 a {
  color: inherit;
  text-decoration: none;
}

.blog-card h2 a:hover {
  color: var(--accent);
}

.article-layout {
  max-width: 860px;
  margin: 0 auto;
}

.article-header {
  margin-bottom: 1.25rem;
}

.article-meta {
  margin: 1rem 0 0 !important;
  color: var(--text-soft);
  font-size: 0.9rem;
}

.article-body {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: clamp(1rem, 3vw, 2rem);
  box-shadow: var(--shadow-sm);
}

.article-body h2 {
  margin: 2rem 0 0.65rem;
  font-family: var(--font-heading);
  line-height: 1.25;
}

.article-body h2:first-of-type {
  margin-top: 1.2rem;
}

.article-body p {
  color: var(--text-soft);
}

.article-figure {
  float: right;
  width: min(42%, 270px);
  margin: 0 0 1rem 1.5rem;
}

.article-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.article-figure figcaption {
  margin-top: 0.4rem;
  color: var(--text-soft);
  font-size: 0.85rem;
  text-align: center;
}

.table-wrap {
  overflow-x: auto;
  margin: 1rem 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 320px;
}

caption {
  margin-bottom: 0.45rem;
  color: var(--text-soft);
  font-size: 0.9rem;
  text-align: left;
}

th,
td {
  border: 1px solid var(--border);
  padding: 0.55rem 0.65rem;
  text-align: left;
}

th {
  background: var(--surface-alt);
  font-family: var(--font-heading);
}

.article-callout {
  clear: both;
  margin-top: 1.5rem;
  padding: 0.9rem 1rem;
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--surface-alt);
  color: var(--text-soft);
}

.related-articles {
  clear: both;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}

.related-articles h2 {
  margin-top: 0;
}

.content-card ul {
  margin: 0.3rem 0 0;
  padding-left: 1.1rem;
}

.roman-chip-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 0 0 0.8rem;
}

.roman-chip {
  border: 1px solid var(--border);
  background: var(--surface-soft);
  color: var(--text);
  border-radius: 999px;
  padding: 0.2rem 0.6rem;
  font-family: var(--font-heading);
  font-size: 0.95rem;
  cursor: pointer;
  min-height: 36px;
}

.roman-chip:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.faq-list {
  display: grid;
  gap: 0.7rem;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.8rem;
  background: var(--surface);
}

.faq-item h3 {
  margin: 0;
  font-size: 1rem;
}

.faq-item p {
  margin: 0.45rem 0 0;
  color: var(--text-soft);
}

.site-footer {
  border-top: 1px solid color-mix(in srgb, var(--border) 76%, transparent);
  padding: 1.2rem 0 2rem;
  color: var(--text-soft);
  font-size: 0.94rem;
}

.site-footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 0.35rem;
}

.site-footer__links a {
  text-decoration: none;
}

.page-title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: clamp(1.6rem, 2.4vw, 2.15rem);
}

.page-intro {
  margin: 0.65rem 0 0;
  color: var(--text-soft);
}

.contact-panel {
  max-width: 760px;
}

textarea {
  min-height: 140px;
  resize: vertical;
}

@media (min-width: 900px) {
  .converter-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    align-items: start;
  }

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

  .content-grid .content-card--wide {
    grid-column: 1 / -1;
  }
}

@media (max-width: 760px) {
  .site-shell {
    width: min(100% - 1.3rem, 740px);
  }

  .site-header {
    position: static;
  }

  .site-header__inner {
    min-height: 64px;
    flex-wrap: nowrap;
    padding: 0.55rem 0;
  }

  .brand span:last-child {
    max-width: 130px;
    line-height: 1.15;
  }

  .nav-menu-toggle {
    display: inline-flex;
    margin-left: auto;
  }

  .site-nav {
    position: absolute;
    display: none;
    top: calc(100% + 0.5rem);
    left: 0;
    right: 0;
    margin: 0;
    padding: 0.65rem;
    flex-direction: column;
    align-items: stretch;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
  }

  .site-header__inner {
    position: relative;
  }

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

  .site-nav a,
  .nav-group__toggle {
    width: 100%;
    text-align: left;
    border-radius: 10px;
  }

  .nav-group__menu {
    position: static;
    min-width: 0;
    margin-top: 0.2rem;
    box-shadow: none;
    background: var(--surface-alt);
  }

  .nav-group__menu a {
    padding-left: 1.25rem;
  }

  .article-figure {
    float: none;
    width: min(100%, 360px);
    margin: 0 auto 1.25rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}