* {
  box-sizing: border-box;
}

html {
  background: #1e1e1e;
}

body {
  margin: 0;
  min-height: 100vh;
  background: #1e1e1e;
  color: #f0f0f0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px;
}

h1 {
  margin: 0 0 20px;
  font-size: 24px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.card {
  border: 1px solid #3a3a3a;
  border-radius: 10px;
  padding: 18px;
  background: #242424;
}

h2 {
  margin: 0 0 8px;
  font-size: 18px;
}

.hint {
  margin: 0 0 16px;
  color: #aaa;
  line-height: 1.4;
}

.field-row {
  display: grid;
  grid-template-columns: 70px minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.amount-row {
  grid-template-columns: 70px minmax(0, 1fr) auto;
}

label {
  font-weight: 500;
}

input,
select,
button {
  min-height: 42px;
  border-radius: 6px;
  border: 1px solid #555;
  font: inherit;
}

input,
select {
  width: 100%;
  padding: 8px 10px;
  background: #181818;
  color: #f0f0f0;
}

select {
  width: auto;
  min-width: 105px;
}

button {
  width: 100%;
  margin-top: 4px;
  padding: 8px 14px;
  background: #333;
  color: #fff;
  cursor: pointer;
}

button:hover {
  background: #3d3d3d;
}

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 3px solid #7aa7ff;
  outline-offset: 2px;
}

hr {
  margin: 18px 0 14px;
  border: 0;
  border-top: 1px solid #444;
}

.result {
  margin: 0;
  font-size: 16px;
  line-height: 1.55;
  white-space: pre-line;
}

.extra {
  margin: 6px 0 0;
  color: #aaa;
}

.difference {
  min-height: 124px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 700px) {
  .container {
    padding: 16px;
  }

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

  .amount-row {
    grid-template-columns: 70px minmax(0, 1fr);
  }

  .amount-row select {
    grid-column: 2;
    width: 100%;
  }
}