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

:root {
  --bg: #f0f4f8;
  --bg-mesh-a: rgb(37 99 235 / 0.08);
  --bg-mesh-b: rgb(14 165 233 / 0.06);
  --surface: #fff;
  --surface-muted: #f8fafc;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-soft: rgb(37 99 235 / 0.1);
  --success: #059669;
  --success-soft: rgb(5 150 105 / 0.08);
  --error: #b91c1c;
  --error-bg: #fef2f2;
  --error-border: #fecaca;
  --radius: 0.625rem;
  --radius-lg: 1rem;
  --shadow-sm: 0 1px 2px rgb(15 23 42 / 0.05);
  --shadow-md:
    0 4px 6px -1px rgb(15 23 42 / 0.07),
    0 2px 4px -2px rgb(15 23 42 / 0.05);
  --shadow-lg:
    0 10px 15px -3px rgb(15 23 42 / 0.08),
    0 4px 6px -4px rgb(15 23 42 / 0.05);
  --font: "DM Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  font-size: 1rem;
  line-height: 1.55;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

.page-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(ellipse 90% 60% at 50% -15%, var(--bg-mesh-a), transparent 55%),
    radial-gradient(ellipse 70% 45% at 100% 30%, var(--bg-mesh-b), transparent 50%),
    radial-gradient(ellipse 55% 35% at 0% 85%, rgb(37 99 235 / 0.05), transparent 45%),
    var(--bg);
}

.wrap {
  max-width: 28rem;
  margin: 0 auto;
  padding: clamp(1.75rem, 5vw, 2.75rem) 1.25rem 3rem;
}

.page {
  position: relative;
}

.hero {
  margin-bottom: 1.75rem;
}

.eyebrow {
  margin: 0 0 0.4rem;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}

h1 {
  font-size: clamp(1.65rem, 4.5vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin: 0 0 0.5rem;
  color: var(--text);
}

.lede {
  margin: 0;
  max-width: 38ch;
  color: var(--muted);
  font-size: 0.9rem;
}

.lede code {
  font-size: 0.82em;
  font-family: ui-monospace, "Cascadia Code", monospace;
  color: #334155;
  background: var(--surface);
  padding: 0.12em 0.4em;
  border-radius: 6px;
  border: 1px solid var(--border);
}

.card {
  border-radius: var(--radius-lg);
  padding: 1.35rem 1.4rem;
  border: 1px solid var(--border);
  background: var(--surface);
}

.card--elevated {
  box-shadow: var(--shadow-md);
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 1.05rem;
}

.field span {
  font-size: 0.8125rem;
  font-weight: 600;
  color: #334155;
}

.field input,
.field select {
  font: inherit;
  color: var(--text);
  padding: 0.65rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface-muted);
  box-shadow: var(--shadow-sm);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.field input::placeholder {
  color: #94a3b8;
}

.field input:hover,
.field select:hover {
  border-color: var(--border-strong);
}

.field input:focus,
.field select:focus {
  outline: none;
  border-color: rgb(37 99 235 / 0.45);
  box-shadow:
    var(--shadow-sm),
    0 0 0 3px rgb(37 99 235 / 0.18);
}

/* Principal only: hide native number spinners */
#principal::-webkit-outer-spin-button,
#principal::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

#principal[type="number"] {
  appearance: textfield;
  -moz-appearance: textfield;
}

.fieldset {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.85rem 0.75rem 0.9rem;
  margin: 0 0 1.05rem;
  background: var(--surface-muted);
}

.fieldset legend {
  font-size: 0.8125rem;
  font-weight: 600;
  color: #334155;
  padding: 0 0.35rem;
}

.segmented {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.45rem;
  padding: 0.2rem;
  border-radius: var(--radius);
  background: #e2e8f0;
}

.segmented__item {
  position: relative;
  margin: 0;
  cursor: pointer;
}

.segmented__item input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.segmented__label {
  display: block;
  text-align: center;
  padding: 0.55rem 0.65rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--muted);
  border-radius: calc(var(--radius) - 2px);
  transition: color 0.15s ease, background 0.15s ease, box-shadow 0.15s ease;
}

.segmented__item input:focus-visible + .segmented__label {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.segmented__item input:checked + .segmented__label {
  color: var(--text);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
}

#frequency-wrap.muted select {
  opacity: 0.55;
  cursor: not-allowed;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  margin-top: 0.35rem;
  padding: 0.78rem 1.1rem;
  font: inherit;
  font-weight: 600;
  letter-spacing: 0.02em;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition:
    transform 0.15s ease,
    box-shadow 0.15s ease,
    filter 0.15s ease;
}

.btn--primary {
  color: #fff;
  background: linear-gradient(135deg, var(--accent) 0%, #1d4ed8 100%);
  box-shadow:
    0 4px 12px -2px rgb(37 99 235 / 0.45),
    var(--shadow-sm);
}

.btn--primary:hover:not(:disabled) {
  filter: brightness(1.05);
  transform: translateY(-1px);
  box-shadow:
    0 8px 20px -4px rgb(37 99 235 / 0.4),
    var(--shadow-sm);
}

.btn--primary:active:not(:disabled) {
  transform: translateY(0);
}

.btn--primary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.btn--primary:disabled {
  opacity: 0.65;
  cursor: not-allowed;
  transform: none;
}

.error {
  margin-top: 1rem;
  padding: 0.85rem 1rem;
  background: var(--error-bg);
  border: 1px solid var(--error-border);
  border-radius: var(--radius);
  color: var(--error);
  font-size: 0.9rem;
  box-shadow: var(--shadow-sm);
}

.results {
  margin-top: 1.35rem;
}

.results__title {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 0.35rem;
  color: var(--text);
}

.results__hint {
  margin: 0 0 1.15rem;
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.45;
}

.grid {
  display: grid;
  grid-template-columns: minmax(0, 7.5rem) 1fr;
  gap: 0;
  margin: 0;
}

.grid--amounts {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface-muted);
}

.grid--amounts > dt,
.grid--amounts > dd {
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--border);
}

.grid--amounts > dt:last-of-type,
.grid--amounts > dd:last-child {
  border-bottom: none;
}

.result-row__label {
  margin: 0;
  align-self: start;
  padding-top: 0.95rem;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
  background: rgb(248 250 252 / 0.85);
}

.result-row {
  margin: 0;
  min-width: 0;
  background: var(--surface);
}

.result-row--hero {
  background: linear-gradient(180deg, var(--success-soft) 0%, var(--surface) 100%);
  border-left: 3px solid var(--success);
  padding-left: calc(1rem - 3px);
}

.result-row--hero .amount-num {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--success);
}

.result-row--apr {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  color: var(--text);
}

.amount-num {
  display: block;
  font-weight: 700;
  font-size: 1.08rem;
  font-variant-numeric: tabular-nums;
  color: var(--text);
}

.amount-words {
  margin: 0.4rem 0 0;
  font-size: 0.8125rem;
  font-weight: 400;
  color: var(--muted);
  line-height: 1.45;
}

@media (max-width: 380px) {
  .grid {
    grid-template-columns: 1fr;
  }

  .grid--amounts > dt {
    padding-bottom: 0.25rem;
    border-bottom: none;
  }

  .grid--amounts > dd {
    padding-top: 0;
  }

  .result-row__label {
    padding-top: 0.75rem;
  }
}