:root {
  --ink: #1a2332;
  --ink-soft: #3d4a5c;
  --paper: #f3efe6;
  --paper-2: #e8e2d4;
  --line: #c9c0ae;
  --accent: #0f6b5c;
  --accent-2: #c45c26;
  --white: #fffcf7;
  --shadow: 0 12px 40px rgba(26, 35, 50, 0.08);
  --font-display: "Fraunces", "Georgia", serif;
  --font-body: "Source Sans 3", "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, monospace;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.05rem;
  line-height: 1.65;
  background:
    radial-gradient(ellipse 80% 50% at 10% -10%, rgba(15, 107, 92, 0.12), transparent 55%),
    radial-gradient(ellipse 60% 40% at 100% 0%, rgba(196, 92, 38, 0.08), transparent 50%),
    linear-gradient(180deg, var(--paper) 0%, var(--paper-2) 100%);
  min-height: 100vh;
}

img {
  max-width: 100%;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--accent-2);
}

.wrap {
  width: min(1080px, calc(100% - 2rem));
  margin-inline: auto;
}

.site-header {
  padding: 1.1rem 0 0.4rem;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem 1.25rem;
}

.brand {
  font-family: var(--font-display);
  font-weight: 650;
  font-size: 1.45rem;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: -0.02em;
}

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

.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--ink-soft);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--accent);
}

.hero {
  padding: 2.5rem 0 1.5rem;
}

.hero h1 {
  font-family: var(--font-display);
  font-weight: 650;
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin: 0 0 0.75rem;
  max-width: 16ch;
}

.hero p {
  margin: 0;
  max-width: 42rem;
  color: var(--ink-soft);
  font-size: 1.12rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1rem;
  margin: 1.75rem 0 2.5rem;
}

.card {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.2rem 1.25rem 1.35rem;
  box-shadow: var(--shadow);
  text-decoration: none;
  color: inherit;
  transition: transform 0.18s ease, border-color 0.18s ease;
}

.card:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
  color: inherit;
}

.card h2 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  margin: 0 0 0.4rem;
}

.card p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.98rem;
}

.panel {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 1.25rem;
  margin: 1.25rem 0 2rem;
}

.calc-shell {
  display: grid;
  gap: 1rem;
}

@media (min-width: 860px) {
  .calc-shell.split {
    grid-template-columns: 1.1fr 0.9fr;
    align-items: start;
  }
}

.display {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #f7f3ea;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 1.55rem;
  padding: 0.9rem 1rem;
  text-align: right;
  min-height: 3.4rem;
}

.keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.55rem;
}

button.key {
  appearance: none;
  border: 1px solid var(--line);
  background: #faf7f0;
  color: var(--ink);
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 1.05rem;
  border-radius: 10px;
  padding: 0.85rem 0.4rem;
  cursor: pointer;
}

button.key:hover {
  border-color: var(--accent);
}

button.key.op {
  background: rgba(15, 107, 92, 0.1);
  color: var(--accent);
}

button.key.eq {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

button.key.warn {
  background: rgba(196, 92, 38, 0.12);
  color: var(--accent-2);
}

.field {
  display: grid;
  gap: 0.35rem;
  margin-bottom: 0.85rem;
}

.field label {
  font-weight: 700;
  font-size: 0.92rem;
}

.field input,
.field select,
.field textarea {
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0.7rem 0.85rem;
  font: inherit;
  background: #fff;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.5rem;
}

.btn {
  appearance: none;
  border: none;
  border-radius: 999px;
  padding: 0.7rem 1.2rem;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  background: var(--accent);
  color: #fff;
}

.btn.secondary {
  background: transparent;
  color: var(--ink-soft);
  border: 1px solid var(--line);
}

.result {
  margin-top: 1rem;
  padding: 0.9rem 1rem;
  border-radius: 12px;
  background: rgba(15, 107, 92, 0.08);
  border: 1px solid rgba(15, 107, 92, 0.2);
  font-family: var(--font-mono);
  font-size: 1.15rem;
}

.prose {
  max-width: 42rem;
}

.prose h2 {
  font-family: var(--font-display);
  font-size: 1.45rem;
  margin: 2rem 0 0.6rem;
}

.prose p,
.prose li {
  color: var(--ink-soft);
}

.site-footer {
  margin-top: 3rem;
  padding: 2rem 0 2.5rem;
  border-top: 1px solid var(--line);
  color: var(--ink-soft);
  font-size: 0.95rem;
}

.site-footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  margin-bottom: 0.85rem;
}

.site-footer a {
  color: var(--ink-soft);
  text-decoration: none;
  font-weight: 600;
}

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

.note {
  font-size: 0.92rem;
  color: var(--ink-soft);
}

.badge {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
}