:root {
  --green-700: #0f6d4f;
  --green-500: #1fbf75;
  --green-300: #54d399;
  --green-100: #e5f7ed;
  --slate-900: #0f172a;
  --slate-700: #334155;
  --slate-500: #64748b;
  --card-bg: #ffffff;
  --border-color: rgba(15, 109, 79, 0.15);
  --shadow: 0 20px 50px rgba(15, 13, 46, 0.15);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", "SF Pro Display", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top, #f3fff7 0%, #d6ffe9 40%, #c7f5e0 70%, #f3fff7 100%);
  color: var(--slate-900);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
}

.calculator {
  width: min(900px, 100%);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

header {
  text-align: center;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.2em;
  font-size: 0.8rem;
  color: var(--green-700);
  margin-bottom: 0.5rem;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
}

.subtitle {
  margin-top: 0.5rem;
  color: var(--slate-500);
}

.card {
  background: var(--card-bg);
  border-radius: 24px;
  padding: 2rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border-color);
}

form.card {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  overflow: hidden;
}

.field-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

label {
  font-weight: 600;
}

.model-picker {
  display: flex !important;
  flex-direction: column !important;
  gap: 0.75rem;
  width: 100%;
}

.model-picker input,
.model-picker select {
  width: 100%;
}

.model-picker > * {
  min-width: 0;
}

input,
select,
button {
  font: inherit;
}

input,
select {
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 0.85rem 1rem;
  background: var(--green-100);
  color: var(--slate-900);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input:focus,
select:focus {
  outline: none;
  border-color: var(--green-500);
  box-shadow: 0 0 0 3px rgba(31, 191, 117, 0.3);
}

select {
  height: 100%;
  width: 100%;
  min-width: 0;
  max-width: 100%;
  display: block;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
}

.markup-controls {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 0.75rem;
  align-items: center;
}

input[type="range"] {
  -webkit-appearance: none;
  background: linear-gradient(90deg, var(--green-500), var(--green-300));
  height: 6px;
  border-radius: 999px;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--card-bg);
  border: 2px solid var(--green-700);
  cursor: pointer;
}

button.primary {
  border: none;
  border-radius: 999px;
  padding: 0.95rem 2rem;
  background: linear-gradient(135deg, var(--green-500), var(--green-700));
  color: white;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

button.primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 25px rgba(15, 109, 79, 0.3);
}

.helper {
  margin: 0;
  color: var(--slate-500);
  min-height: 1.25rem;
}

.helper.error {
  color: #b91c1c;
}

.helper.info {
  color: var(--green-700);
}

.results {
  transition: opacity 0.3s ease;
}

.results.hidden {
  opacity: 0;
  pointer-events: none;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}

.result {
  background: var(--green-100);
  border-radius: 16px;
  padding: 1.25rem;
  border: 1px solid rgba(15, 109, 79, 0.2);
}

.result .label {
  display: block;
  font-size: 0.9rem;
  color: var(--slate-700);
}

.result .value {
  display: block;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--green-700);
}

@media (max-width: 700px) {
  body {
    padding: 1.5rem 1rem;
  }

  .model-picker,
  .markup-controls {
    grid-template-columns: 1fr;
  }
}