:root {
  color-scheme: light;
  --ink: #172033;
  --muted: #5d6879;
  --accent: #0b6e75;
  --accent-dark: #07535a;
  --surface: #ffffff;
  --background: #f3f6f8;
  --border: #d9e0e5;
  --error: #9c2f28;
  font-family: Inter, "Segoe UI", system-ui, -apple-system, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  margin: 0;
  display: flex;
  flex-direction: column;
  color: var(--ink);
  background: var(--background);
  line-height: 1.6;
}

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

.site-header,
.page-shell,
.site-footer {
  width: min(100% - 2rem, 68rem);
  margin-inline: auto;
}

.site-header {
  min-height: 4.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  color: var(--ink);
  font-size: 1.15rem;
  font-weight: 750;
  text-decoration: none;
  letter-spacing: 0.02em;
}

nav {
  display: flex;
  gap: 1.25rem;
}

nav a {
  font-weight: 600;
  text-decoration: none;
}

.page-shell {
  flex: 1;
  padding-block: 3rem;
}

.hero,
.panel {
  max-width: 46rem;
}

.hero {
  padding-block: 2rem 3rem;
}

.panel {
  padding: clamp(1.25rem, 4vw, 2.5rem);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  box-shadow: 0 0.5rem 1.5rem rgb(24 39 54 / 7%);
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  max-width: 18ch;
  margin-bottom: 1rem;
  font-size: clamp(2rem, 6vw, 3.5rem);
  line-height: 1.08;
}

.panel h1 {
  font-size: clamp(1.8rem, 5vw, 2.6rem);
}

.eyebrow {
  margin-bottom: 0.55rem;
  color: var(--accent-dark);
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.intro {
  max-width: 58ch;
  color: var(--muted);
  font-size: 1.15rem;
}

.button-link,
button {
  display: inline-block;
  padding: 0.72rem 1.05rem;
  color: #ffffff;
  background: var(--accent);
  border: 0;
  border-radius: 0.35rem;
  font: inherit;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
}

.button-link:hover,
button:hover {
  background: var(--accent-dark);
}

.calculation-form {
  display: grid;
  gap: 0.65rem;
  max-width: 24rem;
  margin-top: 1.75rem;
}

label {
  font-weight: 700;
}

input {
  width: 100%;
  padding: 0.72rem;
  color: var(--ink);
  background: #ffffff;
  border: 1px solid #9ca8b5;
  border-radius: 0.35rem;
  font: inherit;
}

input:focus,
button:focus,
a:focus {
  outline: 0.2rem solid rgb(11 110 117 / 30%);
  outline-offset: 0.15rem;
}

small {
  color: var(--muted);
}

.calculation-form button {
  justify-self: start;
  margin-top: 0.5rem;
}

.message {
  margin-top: 1.5rem;
  margin-bottom: 0;
  padding: 0.8rem 1rem;
  border-left: 0.3rem solid var(--accent);
  background: #eef8f8;
}

.message-error {
  color: var(--error);
  border-left-color: var(--error);
  background: #fff3f2;
}

.site-footer {
  padding-block: 1.5rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.site-footer p {
  margin: 0;
}

@media (max-width: 34rem) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
    padding-block: 1rem;
  }

  .page-shell {
    padding-block: 1.5rem;
  }
}