header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(242,242,247,0.85);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--ios-separator);
  padding: 12px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

@media (prefers-color-scheme: dark) {
  header { background: rgba(0,0,0,0.75); }
}

h1 {
  font-size: 20px;
  font-weight: 700;
  margin: 0;
  letter-spacing: -0.4px;
}

.lang-switch {
  display: flex;
  gap: 4px;
  background: var(--ios-tertiary);
  padding: 2px;
  border-radius: var(--radius-sm);
}

.lang-switch button {
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s;
}

.lang-switch button.active {
  background: var(--ios-card);
  color: var(--text-primary);
  box-shadow: var(--shadow);
}

.container {
  width: 100%;
  padding: 16px 0;
}

.form-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  align-items: flex-end;
}

.form-group {
  flex: 1;
  min-width: 140px;
}

label {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--ios-secondary);
  margin-bottom: 4px;
}

.actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
  flex-wrap: wrap;
}

.chart-wrap {
  position: relative;
  height: 280px;
  margin: 12px 0;
}

.output {
  margin-top: 8px;
}

footer {
  text-align: center;
  font-size: 12px;
  color: var(--ios-secondary);
  margin-top: 24px;
  padding: 0 16px;
}

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--ios-primary);
  outline-offset: 2px;
}