* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #f8fafc;
  --bg-subtle: #f1f5f9;
  --surface: #ffffff;
  --surface-card: #ffffff;
  --surface-soft: #f8fafc;
  --surface-hover: #f1f5f9;
  --text: #0f172a;
  --text-muted: #64748b;
  --text-dim: #94a3b8;
  --border: #e2e8f0;
  --border-focus: #3b82f6;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-soft: rgba(37, 99, 235, 0.08);
  --primary-glow: rgba(37, 99, 235, 0.15);
  --success: #10b981;
  --success-soft: rgba(16, 185, 129, 0.1);
  --shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 20px 40px -15px rgba(0, 0, 0, 0.12);
  --radius: 16px;
  --radius-sm: 10px;
  --radius-lg: 24px;
}

.dark,
[data-theme="dark"] {
  --bg: #0f0f11;
  --bg-subtle: #141417;
  --surface: #141417;
  --surface-card: #18181c;
  --surface-soft: #1e1e24;
  --surface-hover: #26262e;
  --text: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --border: #27272f;
  --border-focus: #3b82f6;
  --primary: #3b82f6;
  --primary-hover: #60a5fa;
  --primary-soft: rgba(59, 130, 246, 0.12);
  --primary-glow: rgba(59, 130, 246, 0.2);
  --success: #10b981;
  --success-soft: rgba(16, 185, 129, 0.15);
  --shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 20px 40px -15px rgba(0, 0, 0, 0.7);
}

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  font-family: "Geist", Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.5;
  transition: background-color 0.3s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
}

button,
input,
select,
textarea {
  font: inherit;
  color: inherit;
}

button,
label,
select {
  -webkit-tap-highlight-color: transparent;
}

.calculator-shell {
  width: min(860px, calc(100% - 32px));
  margin: 32px auto 60px;
}

/* Nav Header */
.top-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  padding: 0 8px;
}

.top-nav a.brand {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 8px;
  letter-spacing: -0.02em;
}

.top-nav a.brand:hover {
  opacity: 0.85;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-toggle-btn {
  background: var(--surface-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  width: 40px;
  height: 40px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
}

.theme-toggle-btn:hover {
  color: var(--text);
  border-color: var(--primary);
  background: var(--surface-hover);
}

.home-btn {
  font-size: 0.85rem;
  color: var(--text-muted);
  text-decoration: none;
  padding: 8px 14px;
  border-radius: 999px;
  background: var(--surface-card);
  border: 1px solid var(--border);
  transition: all 0.2s ease;
  font-family: "JetBrains Mono", monospace;
}

.home-btn:hover {
  color: var(--text);
  border-color: var(--primary);
}

/* Main Card */
.calculator-card {
  background: var(--surface-card);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: border-color 0.3s ease, background-color 0.3s ease;
}

.hero {
  padding: 36px 36px 20px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, var(--surface-soft) 0%, var(--surface-card) 100%);
}

.developer-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--primary);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  background: var(--primary-soft);
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid var(--primary-glow);
  margin-bottom: 12px;
}

.hero h1 {
  margin: 6px 0 10px;
  font-size: clamp(1.6rem, 3.5vw, 2.2rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
  color: var(--text);
}

.hero p {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.5;
  max-width: 650px;
}

/* Progress */
.progress-wrap {
  padding: 20px 36px 0;
}

.progress-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  color: var(--text-muted);
  font-size: 0.8rem;
  font-family: "JetBrains Mono", monospace;
  font-weight: 500;
  margin-bottom: 8px;
}

.progress-track {
  height: 6px;
  border-radius: 999px;
  background: var(--surface-soft);
  border: 1px solid var(--border);
  overflow: hidden;
}

.progress-bar {
  width: 14%;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--primary), #60a5fa);
  transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Form & Steps */
form {
  padding: 28px 36px 36px;
}

.step {
  display: none;
  animation: fadeUp 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.step.is-active {
  display: block;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.step-heading {
  margin-bottom: 22px;
}

.step-kicker {
  display: inline-block;
  color: var(--primary);
  font-family: "JetBrains Mono", monospace;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 4px;
}

.step-heading h2,
.estimate-head h2 {
  margin: 4px 0 6px;
  font-size: clamp(1.3rem, 2.5vw, 1.7rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}

.step-heading p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Option Cards & Grids */
.option-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
  margin-bottom: 18px;
}

.option-grid--2 {
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.option-card {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 16px 16px;
  border-radius: var(--radius);
  background: var(--surface-soft);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all 0.2s ease;
  user-select: none;
}

.option-card:hover {
  background: var(--surface-hover);
  border-color: var(--border-focus);
  transform: translateY(-1px);
}

.option-card input[type="radio"],
.option-card input[type="checkbox"] {
  margin-top: 3px;
  accent-color: var(--primary);
  width: 17px;
  height: 17px;
  cursor: pointer;
  flex-shrink: 0;
}

.option-card:has(input:checked) {
  background: var(--primary-soft);
  border-color: var(--primary);
  box-shadow: 0 0 0 1px var(--primary);
}

.option-icon {
  font-size: 1.3rem;
  line-height: 1;
  flex-shrink: 0;
}

.option-copy {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.option-copy strong {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text);
}

.option-copy small {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.35;
}

/* Fields & Selects */
.field-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.field span {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
}

.field select,
.field textarea {
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  background: var(--surface-soft);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 0.9rem;
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.field select:focus,
.field textarea:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-soft);
}

/* Feature Recommendation Box */
.recommended-box {
  margin: 18px 0;
  padding: 16px 18px;
  border-radius: var(--radius);
  background: var(--primary-soft);
  border: 1px solid var(--primary-glow);
}

.recommended-box h3 {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.recommended-box p {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.feature-group-title {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin: 18px 0 10px;
}

/* Alert Message */
.form-alert {
  display: none;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: #ef4444;
  font-size: 0.85rem;
  margin-bottom: 18px;
}

.form-alert.is-visible {
  display: block;
}

/* Navigation Buttons */
.form-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  gap: 12px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 1px solid transparent;
  text-decoration: none;
}

.btn:active {
  transform: scale(0.98);
}

.btn--primary {
  background: var(--primary);
  color: #ffffff;
}

.btn--primary:hover {
  background: var(--primary-hover);
  box-shadow: 0 4px 14px var(--primary-glow);
}

.btn--ghost {
  background: var(--surface-soft);
  border-color: var(--border);
  color: var(--text-muted);
}

.btn--ghost:hover {
  background: var(--surface-hover);
  color: var(--text);
  border-color: var(--border-focus);
}

.btn--success {
  background: var(--success);
  color: #ffffff;
}

.btn--success:hover {
  background: #059669;
}

/* Estimate Result Step */
.estimate-head {
  margin-bottom: 24px;
}

.result-hero {
  background: var(--surface-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 22px;
}

.result-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 8px;
}

.result-price {
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 800;
  color: var(--text);
  letter-spacing: -0.03em;
  margin: 6px 0;
}

.result-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 8px;
}

.result-meta-item {
  display: flex;
  align-items: center;
  gap: 5px;
}

/* Breakdown & Requirements */
.breakdown-box {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  background: var(--surface-card);
  margin-bottom: 18px;
}

.breakdown-title {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.breakdown-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  font-size: 0.88rem;
  border-bottom: 1px solid var(--border);
}

.breakdown-row:last-child {
  border-bottom: none;
}

.breakdown-row span:first-child {
  color: var(--text-muted);
}

.breakdown-row span:last-child {
  font-weight: 600;
  font-family: "JetBrains Mono", monospace;
  color: var(--text);
}

/* Tag clouds */
.tags-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.tag {
  background: var(--surface-soft);
  border: 1px solid var(--border);
  padding: 5px 12px;
  border-radius: 999px;
  font-size: 0.78rem;
  color: var(--text);
  font-family: "JetBrains Mono", monospace;
}

/* Share & Action Grid */
.estimate-actions {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin: 24px 0 16px;
}

.code-pill {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--surface-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.82rem;
  margin-top: 14px;
}

.code-pill code {
  color: var(--primary);
  font-weight: 600;
}

/* Developer Guarantee / Support Box */
.support-notice {
  background: var(--success-soft);
  border: 1px solid rgba(16, 185, 129, 0.25);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin-top: 18px;
  font-size: 0.83rem;
  color: var(--text-muted);
  line-height: 1.45;
}

.support-notice strong {
  color: var(--success);
  display: block;
  margin-bottom: 4px;
}

@media (max-width: 640px) {
  .calculator-shell {
    width: 100%;
    margin: 16px auto 40px;
    padding: 0 12px;
  }
  .hero {
    padding: 24px 20px 16px;
  }
  .progress-wrap {
    padding: 16px 20px 0;
  }
  form {
    padding: 20px 20px 24px;
  }
  .option-grid {
    grid-template-columns: 1fr;
  }
  .form-nav {
    flex-direction: column-reverse;
  }
  .form-nav button {
    width: 100%;
  }
}