:root {
  --bg:      #f7f9fc;
  --card:    #ffffff;
  --primary: #0052cc;
  --muted:   #6b778c;
}

* {
  box-sizing: border-box;
  margin: 0; padding: 0;
}

body {
  height: 100vh;
  font-family: system-ui, sans-serif;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.panel {
  width: 100%;
  height: 130px;
  background: var(--card);
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,.08);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

h1 {
  font-size: 1.1rem;
  color: var(--primary);
  text-align: center;
  margin-bottom: 0.5rem;
}

/* single‐card area */
.card-wrapper {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.code {
  font-size: 1rem;
  color: var(--muted);
  margin-bottom: 0.25rem;
}

.rate {
  font-size: 1.75rem;
  color: var(--primary);
}

/* nav buttons */
.nav {
  background: rgba(255,255,255,0.9);
  border: 1px solid var(--primary);
  color: var(--primary);
  width: 32px;
  height: 32px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1.25rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* footer */
.updated {
  font-size: 0.75rem;
  color: var(--muted);
  text-align: right;
  margin-top: 0.5rem;
}

.error {
  font-size: 0.85rem;
  color: crimson;
  text-align: center;
  margin-top: 0.25rem;
}
