:root {
  --color-white: #ffffff;
  --color-almost-white: #bdd5ee;
  --color-main: #7796b6;
  --color-dark: #385471;
  --color-black: #000000;
  --gradient-main: linear-gradient(135deg, var(--color-main) 0%, var(--color-dark) 100%);
  --font-sans: system-ui, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --radius: 8px;
  --shadow: 0 2px 8px rgba(56, 84, 113, 0.12);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-sans);
  color: var(--color-dark);
  background: var(--color-white);
  line-height: 1.45;
}

.app-header {
  background: var(--gradient-main);
  color: var(--color-white);
  padding: 1rem 1.25rem 1.25rem;
  box-shadow: var(--shadow);
}

.app-header h1 {
  margin: 0 0 0.75rem;
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.pref-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1.25rem;
}

.pref-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.pref-group span {
  font-size: 0.85rem;
  opacity: 0.95;
}

.segmented {
  display: inline-flex;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.35);
}

.segmented button {
  font: inherit;
  padding: 0.4rem 0.75rem;
  border: none;
  background: rgba(255, 255, 255, 0.15);
  color: var(--color-white);
  cursor: pointer;
  min-height: 2.25rem;
}

.segmented button:hover {
  background: rgba(255, 255, 255, 0.28);
}

.segmented button[aria-pressed="true"] {
  background: var(--color-white);
  color: var(--color-dark);
  font-weight: 600;
}

.segmented button:focus-visible {
  outline: 2px solid var(--color-white);
  outline-offset: 2px;
}

main {
  max-width: 52rem;
  margin: 0 auto;
  padding: 1rem 1.25rem 2.5rem;
}

.tablist {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0 0 1rem;
  padding: 0;
  list-style: none;
}

.tablist button {
  font: inherit;
  padding: 0.5rem 0.85rem;
  border: 1px solid var(--color-main);
  border-radius: var(--radius);
  background: var(--color-almost-white);
  color: var(--color-dark);
  cursor: pointer;
  min-height: 2.5rem;
}

.tablist button:hover {
  background: var(--color-white);
}

.tablist button[aria-selected="true"] {
  background: var(--gradient-main);
  color: var(--color-white);
  border-color: var(--color-dark);
}

.tablist button:focus-visible {
  outline: 2px solid var(--color-dark);
  outline-offset: 2px;
}

.panel {
  background: var(--color-almost-white);
  border: 1px solid rgba(119, 150, 182, 0.5);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem 1.35rem;
  box-shadow: var(--shadow);
  position: relative;
  overflow: visible;
  isolation: isolate;
}

.panel[hidden] {
  display: none !important;
}

/*
 * Native <select> dropdowns stack with later DOM siblings; following blocks
 * (details, disclaimers, next field rows) paint on top unless we raise select rows.
 */
.panel .field-grid:has(select) {
  position: relative;
  z-index: 4;
}

.panel details.coating-help,
.panel .disclaimer,
.panel .warning {
  position: relative;
  z-index: 0;
}

/* Keep number-only rows below open select popups */
.panel .field-grid:not(:has(select)) {
  position: relative;
  z-index: 0;
}

.panel h2 {
  margin: 0 0 0.75rem;
  font-size: 1.15rem;
  color: var(--color-dark);
}

.panel > p.hint {
  margin: 0 0 1rem;
  font-size: 0.9rem;
  color: var(--color-dark);
  opacity: 0.9;
}

.field-grid {
  display: grid;
  gap: 0.75rem;
}

@media (min-width: 36rem) {
  .field-grid.two {
    grid-template-columns: 1fr 1fr;
  }
}

label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-dark);
  margin-bottom: 0.25rem;
}

input[type="text"],
input[type="number"],
select,
textarea {
  width: 100%;
  max-width: 100%;
  font: inherit;
  padding: 0.45rem 0.55rem;
  border: 1px solid var(--color-main);
  border-radius: 6px;
  background: var(--color-white);
  color: var(--color-black);
}

input:disabled,
select:disabled {
  opacity: 0.65;
  cursor: not-allowed;
}

textarea {
  min-height: 6rem;
  font-family: ui-monospace, "Cascadia Code", Consolas, monospace;
  font-size: 0.85rem;
}

button.primary {
  font: inherit;
  padding: 0.5rem 1rem;
  border: none;
  border-radius: var(--radius);
  background: var(--gradient-main);
  color: var(--color-white);
  cursor: pointer;
  min-height: 2.5rem;
}

button.primary:hover {
  filter: brightness(1.05);
}

button.primary:focus-visible {
  outline: 2px solid var(--color-dark);
  outline-offset: 2px;
}

.results {
  margin-top: 1rem;
  padding: 0.75rem 1rem;
  background: var(--color-white);
  border: 1px dashed var(--color-main);
  border-radius: var(--radius);
  font-size: 0.95rem;
}

.results strong {
  color: var(--color-dark);
}

.disclaimer {
  margin-top: 0.75rem;
  padding: 0.6rem 0.75rem;
  font-size: 0.8rem;
  background: rgba(255, 255, 255, 0.7);
  border-left: 3px solid var(--color-dark);
  border-radius: 4px;
}

.warning {
  margin: 0.75rem 0;
  padding: 0.6rem 0.75rem;
  font-size: 0.85rem;
  background: #fff8f0;
  border: 2px solid var(--color-dark);
  border-radius: var(--radius);
}

.warning[hidden] {
  display: none !important;
}

.error-text {
  margin-top: 0.35rem;
  font-size: 0.85rem;
  color: var(--color-black);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 2px;
}

details.coating-help {
  margin: 0.75rem 0;
  font-size: 0.85rem;
}

details.coating-help summary {
  cursor: pointer;
  color: var(--color-dark);
  font-weight: 600;
}

.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;
}