:root {
  --ink: #17324d;
  --teal: #16758b;
  --teal-dark: #10586a;
  --soft: #eaf4f7;
  --paper: #ffffff;
  --muted: #667785;
  --line: #d7e2e8;
  --warn: #fff4e5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Calibri, Arial, sans-serif;
  color: var(--ink);
  background: linear-gradient(135deg, #eef5f7, #f8fafb);
  min-height: 100vh;
}

.app-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 32px 18px;
}

.converter-card {
  width: min(720px, 100%);
  background: var(--paper);
  border-radius: 22px;
  box-shadow: 0 18px 55px rgba(23, 50, 77, 0.14);
  overflow: hidden;
  border: 1px solid rgba(23, 50, 77, 0.08);
}

.hero {
  padding: 34px 38px 25px;
  background: linear-gradient(120deg, var(--ink), var(--teal));
  color: white;
}

.eyebrow {
  display: inline-block;
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  opacity: 0.82;
  margin-bottom: 10px;
}

h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  margin: 0 0 8px;
}

.hero p {
  margin: 0;
  max-width: 560px;
  line-height: 1.5;
  opacity: 0.9;
}

.panel {
  padding: 30px 38px 34px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.field label {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--muted);
  text-transform: uppercase;
}

input,
select {
  width: 100%;
  padding: 14px 15px;
  border: 1px solid var(--line);
  border-radius: 11px;
  background: #fbfcfd;
  color: var(--ink);
  font: inherit;
  outline: none;
  transition: 0.2s;
}

input:focus,
select:focus {
  border-color: var(--teal);
  box-shadow: 0 0 0 3px rgba(22, 117, 139, 0.12);
}

.currency-grid {
  display: grid;
  grid-template-columns: 1fr 52px 1fr;
  gap: 14px;
  align-items: end;
  margin: 18px 0 22px;
}

.swap {
  height: 48px;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: var(--soft);
  font-size: 1.45rem;
  color: var(--teal);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.2s, background-color 0.2s;
}

.swap:hover {
  transform: translateY(-1px);
  background: #dceef2;
}

.primary {
  width: 100%;
  border: 0;
  border-radius: 11px;
  padding: 15px 18px;
  background: var(--teal);
  color: white;
  font-weight: 700;
  font-size: 1rem;
  cursor: pointer;
  transition: background-color 0.2s;
}

.primary:hover {
  background: var(--teal-dark);
}

.primary:disabled {
  opacity: 0.55;
  cursor: wait;
}

.result {
  margin-top: 22px;
  padding: 22px;
  border-radius: 14px;
  background: var(--soft);
  border-left: 5px solid var(--teal);
  display: grid;
  gap: 6px;
}

.result-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--teal);
}

.result strong {
  font-size: 1.35rem;
}

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

.result.error {
  background: var(--warn);
  border-left-color: #b56b13;
}

.history-panel {
  margin-top: 28px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.history-panel h2 {
  margin: 0 0 16px;
  font-size: 1.25rem;
}

.date-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-bottom: 16px;
}

.secondary {
  width: 100%;
  border: 1px solid var(--teal);
  border-radius: 11px;
  padding: 12px 18px;
  background: white;
  color: var(--teal-dark);
  font-weight: 700;
  cursor: pointer;
}

.secondary:disabled {
  opacity: 0.55;
  cursor: wait;
}

.history-message {
  margin: 14px 0 8px;
  color: var(--muted);
  font-size: 0.9rem;
}

.chart-container {
  width: 100%;
  height: 280px;
  position: relative;
}

.footer-note {
  text-align: center;
  padding: 0 20px 22px;
  color: var(--muted);
  font-size: 0.78rem;
}

.footer-note p {
  margin: 4px 0;
}

.footer-note .repo-link {
  color: var(--teal);
  text-decoration: none;
  font-weight: 700;
  transition: color 0.2s, text-decoration 0.2s;
}

.footer-note .repo-link:hover {
  color: var(--teal-dark);
  text-decoration: underline;
}

@media (max-width: 600px) {
  .hero,
  .panel {
    padding-left: 22px;
    padding-right: 22px;
  }

  .currency-grid {
    grid-template-columns: 1fr 46px 1fr;
    gap: 8px;
  }

  .swap {
    height: 44px;
  }

  .field label {
    font-size: 0.72rem;
  }

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