* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  background: #fff;
  color: #000;
  font-family: 'Courier New', Courier, monospace;
  padding: 20px;
}
.container {
  max-width: 900px;
  margin: 40px auto;
  border: 4px solid #000;
  padding: 20px;
}
header {
  border-bottom: 4px solid #000;
  margin-bottom: 20px;
  padding-bottom: 10px;
}
header h1 {
  font-size: 2rem;
}
.header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
label {
  display: block;
  margin-bottom: 10px;
  font-weight: bold;
}
input[type="number"],
select,
button {
  width: 100%;
  border: 4px solid #000;
  padding: 10px;
  font-size: 1rem;
  background: transparent;
  color: #000;
  font-family: inherit;
}
.input-section {
  margin-bottom: 20px;
}
/* Make inputs flexible and unit selects narrower in input sections */
.input-section > div > input,
.input-section > div > select {
  width: auto;
}
.input-section > div > input {
  flex: 1;
}
.input-section > div > select {
  flex: 0 0 4rem;
  width: 8rem;
  min-width: 8rem;
  max-width: 8rem;
}
/* Remove number input spinner arrows for cleaner text-box appearance */
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
input[type="number"] {
  -moz-appearance: textfield;
}
button {
  cursor: pointer;
  margin-top: 10px;
}
button:hover {
  background: #000;
  color: #fff;
}
.results-section {
  margin-top: 20px;
  border-top: 4px solid #000;
  padding-top: 10px;
}
.result-item {
  margin-top: 20px;
}
.result-item h3 {
  font-size: 1.2rem;
  margin-bottom: 5px;
}
.result-item p {
  padding: 10px;
  border: 4px solid #000;
  background: #fff;
}
.primary-result h3 {
  font-size: 1.4rem;
}
.primary-result p {
  font-weight: normal;
}
/* Style for formula description below the result */
.result-item .formula {
  margin-top: 5px;
  font-size: 0.9rem;
  font-style: italic;
  border: none;
  background: transparent;
  padding: 0;
}
.header-stack {
  margin-top: 10px;
  margin-bottom: 20px;
  display: flex;
  flex-direction: column;
  gap: 2px;
  max-width: 300px;
}
.header-layer {
  border: 2px solid #000;
  padding: 4px;
  background: #f0f0f0;
  text-align: center;
  font-size: 0.9rem;
}
.help-icon {
  display: inline-block;
  margin-left: 4px;
  border: 2px solid #000;
  border-radius: 50%;
  width: 1em;
  height: 1em;
  line-height: 0.9em;
  font-size: 0.8em;
  text-align: center;
  cursor: help;
}
.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;
}
.theme-toggle-btn {
  width: auto;
  margin-left: 10px;
  border: 2px solid #000;
  padding: 2px 6px;
  font-size: 0.8rem;
  background: transparent;
  color: #000;
  font-family: inherit;
}
@media (max-width: 600px) {
  .container {
    margin: 20px;
    padding: 15px;
  }
  header h1 {
    font-size: 1.5rem;
  }
}
body.dark {
  background: #000;
  color: #fff;
}
body.dark .container,
body.dark header {
  border-color: #fff;
}
body.dark input[type="number"],
body.dark select,
body.dark button {
  border-color: #fff;
  background: #333;
  color: #fff;
}
body.dark button:hover {
  background: #fff;
  color: #000;
}
/* Dark mode: make results section border visible */
body.dark .results-section {
  border-color: #fff;
}
/* Dark mode: style result output blocks */
body.dark .result-item p:not(.formula) {
  background: #333;
  border-color: #fff;
  color: #fff;
}
body.dark .header-layer {
  border-color: #fff;
  background: #333;
  color: #fff;
}
body.dark .help-icon {
  border-color: #fff;
  color: #fff;
}