:root {
  --bg: #07111b;
  --panel: #101d2b;
  --text: #f4f7fb;
  --muted: #aab8c5;
  --accent: #38a8e8;
  --accent-soft: #1f6f9f;
  --border: #25384a;
  --danger: #ff6b6b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  display: flex;
  justify-content: center;
  padding: 24px;
}

.app {
  width: 100%;
  max-width: 720px;
  padding-top: 20px;
}

header {
  margin-bottom: 24px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 16px;
}

h1 {
  margin: 0 0 8px;
  font-size: clamp(2rem, 7vw, 4rem);
  line-height: 0.85;
  letter-spacing: -0.06em;
  text-transform: uppercase;
}

h2 {
  margin: 0;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.subtitle {
  margin: 0;
  color: var(--text);
  font-size: 1rem;
}

.install-note {
  margin: 16px 0 0;
  padding: 12px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  color: var(--text);
  font-size: 0.95rem;
}

main {
  display: grid;
  gap: 16px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 18px;
}

.input-card {
  display: grid;
  gap: 16px;
}

label {
  display: block;
  margin-bottom: 6px;
  color: var(--text);
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
}

input {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px;
  background: #050505;
  color: var(--text);
  font-size: 1.1rem;
}

input:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.field-grid {
  display: grid;
  gap: 14px;
}

button {
  width: 100%;
  border: 0;
  border-radius: 18px;
  padding: 16px;
  background: linear-gradient(90deg, var(--accent-soft), var(--accent));
  color: #f4f7fb;
  font-weight: 900;
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  cursor: pointer;
  box-shadow: 0 0 20px rgba(56, 168, 232, 0.15);
}

button:active {
  transform: translateY(1px);
}

.counter-toggle {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.counter-option {
  background: #050505;
  color: var(--muted);
  border: 1px solid var(--border);
  box-shadow: none;
  border-radius: 14px;
  padding: 12px;
  font-size: 0.85rem;
}

.counter-option.active {
  background: linear-gradient(90deg, var(--accent-soft), var(--accent));
  color: #f4f7fb;
  border-color: var(--accent);
}

.helper-text {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.85rem;
  line-height: 1.35;
}

.heckle {
  color: var(--muted);
  font-weight: 400;
  font-style: italic;
  font-size: 0.9rem;
  letter-spacing: 0.02em;
  min-height: 1.5em;
  opacity: 0.85;
  line-height: 1.35;
}

.inline-heckle {
  margin-top: 2px;
  padding-top: 14px;
  border-top: 1px dashed var(--border);
}

.error {
  color: var(--danger);
  font-weight: 800;
  margin-top: 8px;
}

.results {
  display: none;
}

.results.active {
  display: block;
}

.result-grid {
  display: grid;
  gap: 10px;
  margin-top: 14px;
}

.result-row {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px dashed var(--border);
  padding-bottom: 8px;
}

.result-row strong {
  color: var(--muted);
}

.result-row span {
  font-weight: 900;
  text-align: right;
}

.why {
  margin-top: 16px;
  color: var(--muted);
  line-height: 1.5;
}

.details {
  margin-top: 16px;
  color: var(--muted);
}

.details summary {
  cursor: pointer;
  color: var(--accent);
  font-weight: 800;
}

.breakdown {
  margin-top: 12px;
  display: grid;
  gap: 6px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

footer {
  margin-top: 24px;
  color: var(--text);
  font-size: 0.9rem;
  text-align: center;
}

footer strong {
  color: var(--text);
}

.venmo-button {
  display: inline-block;
  margin-top: 10px;
  padding: 12px 16px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: #f4f7fb;
  font-weight: 900;
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.venmo-button:active {
  transform: translateY(1px);
}

a {
  color: var(--accent);
}

@media (max-width: 520px) {
  body {
    padding: 16px;
  }

  header {
    margin-bottom: 18px;
    padding-bottom: 14px;
  }

  h1 {
    font-size: clamp(2.4rem, 14vw, 4rem);
    line-height: 0.84;
    letter-spacing: -0.06em;
  }

  .subtitle {
    font-size: 0.95rem;
    line-height: 1.35;
  }

  .install-note {
    font-size: 0.9rem;
    line-height: 1.35;
  }

  .card {
    padding: 16px;
  }

  input {
    font-size: 1rem;
    padding: 13px;
  }

  button {
    padding: 15px;
    font-size: 0.95rem;
  }

  .result-row {
    align-items: flex-start;
  }

  .result-row strong {
    max-width: 55%;
  }

  .result-row span {
    max-width: 45%;
    word-break: keep-all;
  }

  footer {
    font-size: 0.85rem;
    line-height: 1.4;
  }

  .venmo-button {
    padding: 11px 15px;
    font-size: 0.85rem;
  }
}

@media (max-width: 380px) {
  body {
    padding: 12px;
  }

  h1 {
    font-size: clamp(2rem, 13vw, 3.2rem);
  }

  .card {
    padding: 14px;
  }
}