/* ===== CSS Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --color-bg: #f5f4f0;
  --color-surface: #ffffff;
  --color-surface-alt: #eae8e2;
  --color-primary: #2d6a4f;
  --color-primary-light: #40916c;
  --color-primary-dark: #1b4332;
  --color-accent: #d4a373;
  --color-accent-dark: #b08968;
  --color-text: #2c2c2c;
  --color-text-muted: #6b6b6b;
  --color-text-light: #8a8a8a;
  --color-border: #d6d3cc;
  --color-warning: #c0392b;
  --color-warning-bg: #fdf0ef;
  --color-tip: #2d6a4f;
  --color-tip-bg: #edf5f1;
  --color-success: #2d6a4f;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  --max-width: 1160px;
  --transition: 0.2s ease;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover, a:focus-visible { color: var(--color-primary-dark); text-decoration: underline; }

img { max-width: 100%; height: auto; }

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  background: var(--color-primary);
  color: #fff;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  z-index: 1000;
  font-weight: 600;
}
.skip-link:focus { top: 16px; }

/* ===== Header ===== */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  gap: 16px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  flex-shrink: 0;
}
.logo:hover, .logo:focus-visible { text-decoration: none; }

.logo-icon { flex-shrink: 0; }

.logo-text {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.5px;
}
.logo-accent { color: var(--color-primary); }

.main-nav ul {
  display: flex;
  list-style: none;
  gap: 24px;
}

.main-nav a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: color var(--transition), border-color var(--transition);
}
.main-nav a:hover,
.main-nav a:focus-visible,
.main-nav a[aria-current="page"] {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
  text-decoration: none;
}

/* ===== Hero ===== */
.hero-section {
  background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 60%, var(--color-primary-light) 100%);
  color: #fff;
  padding: 48px 0;
}

.hero-content { max-width: 700px; }

.hero-content h1 {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

.hero-subtitle {
  font-size: 1.05rem;
  opacity: 0.9;
  line-height: 1.5;
}

/* ===== Estimator Section ===== */
.estimator-section {
  padding: 40px 0;
}

.estimator-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 32px;
  align-items: start;
}

.calculator-panel {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
}

.calculator-panel h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 24px;
  color: var(--color-primary-dark);
}

/* ===== Form Elements ===== */
.form-group { margin-bottom: 20px; }
.form-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
}

fieldset.form-group { border: none; padding: 0; }

.material-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.material-option { cursor: pointer; }

.material-option input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.material-card {
  display: flex;
  flex-direction: column;
  padding: 14px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  transition: border-color var(--transition), background var(--transition), box-shadow var(--transition);
  height: 100%;
}

.material-option input:focus-visible + .material-card {
  outline: 3px solid var(--color-primary-light);
  outline-offset: 2px;
}

.material-option input:checked + .material-card {
  border-color: var(--color-primary);
  background: #edf5f1;
  box-shadow: 0 0 0 1px var(--color-primary);
}

.material-name {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--color-text);
}

.material-desc {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 2px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.input-with-unit {
  display: flex;
  align-items: center;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  overflow: hidden;
  transition: border-color var(--transition);
}

.input-with-unit:focus-within {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(45, 106, 79, 0.15);
}

.input-with-unit input {
  border: none;
  background: transparent;
  padding: 10px 12px;
  font-size: 1rem;
  font-family: var(--font-sans);
  color: var(--color-text);
  width: 100%;
  outline: none;
  -moz-appearance: textfield;
}

.input-with-unit input::-webkit-outer-spin-button,
.input-with-unit input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.input-unit {
  padding: 10px 12px 10px 0;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  font-weight: 500;
  white-space: nowrap;
}

select {
  width: 100%;
  padding: 10px 12px;
  font-size: 1rem;
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M2 4l4 4 4-4' fill='none' stroke='%236b6b6b' stroke-width='2'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

select:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(45, 106, 79, 0.15);
}

.form-help {
  display: block;
  font-size: 0.8rem;
  color: var(--color-text-light);
  margin-top: 4px;
}

/* ===== Presets ===== */
.presets {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-bottom: 24px;
  padding-top: 4px;
}

.presets-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
  margin-right: 4px;
}

.preset-btn {
  font-size: 0.78rem;
  font-family: var(--font-sans);
  padding: 5px 12px;
  border: 1px solid var(--color-border);
  border-radius: 20px;
  background: var(--color-bg);
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.preset-btn:hover,
.preset-btn:focus-visible {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
  outline: none;
}

/* ===== Result Panel ===== */
.result-panel {
  background: linear-gradient(135deg, #edf5f1 0%, #e8f0ec 100%);
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid #c8ddd3;
  margin-top: 8px;
}

.result-main {
  text-align: center;
  margin-bottom: 16px;
}

.result-value {
  font-size: 3rem;
  font-weight: 800;
  color: var(--color-primary-dark);
  line-height: 1;
}

.result-unit {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-left: 4px;
}

.result-alt {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  margin-top: 4px;
}

.result-details {
  margin-bottom: 16px;
}

.result-tip {
  font-size: 0.9rem;
  color: var(--color-text);
  margin-bottom: 12px;
  line-height: 1.5;
}

.result-bar {
  height: 8px;
  background: #c8ddd3;
  border-radius: 4px;
  overflow: hidden;
  margin-bottom: 8px;
}

.result-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary-light), var(--color-primary));
  border-radius: 4px;
  transition: width 0.4s ease;
  width: 0%;
}

.result-note {
  font-size: 0.78rem;
  color: var(--color-text-light);
  text-align: center;
}

.result-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  font-size: 0.9rem;
  font-weight: 600;
  font-family: var(--font-sans);
  border-radius: var(--radius-sm);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn:hover, .btn:focus-visible { text-decoration: none; }

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}
.btn-primary:hover, .btn-primary:focus-visible {
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #fff;
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.btn-secondary:hover, .btn-secondary:focus-visible {
  background: var(--color-primary);
  color: #fff;
}

/* ===== Reference Panel ===== */
.reference-panel {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
  position: sticky;
  top: 80px;
}

.reference-panel h2 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 20px;
}

.ref-section { margin-bottom: 24px; }
.ref-section:last-child { margin-bottom: 0; }

.ref-section h3 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 6px;
}

.ref-note {
  font-size: 0.78rem;
  color: var(--color-text-light);
  margin-bottom: 8px;
}

.ref-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
}

.ref-table th,
.ref-table td {
  padding: 7px 10px;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.ref-table th {
  font-weight: 600;
  color: var(--color-text-muted);
  background: var(--color-bg);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.3px;
}

.ref-table td { color: var(--color-text); }
.ref-table tr:last-child td { border-bottom: none; }
.ref-table tr:hover td { background: var(--color-bg); }

/* ===== Guide Section ===== */
.guide-section {
  padding: 48px 0;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
}

.guide-section h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 28px;
  text-align: center;
}

.guide-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.guide-card {
  background: var(--color-bg);
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid var(--color-border);
  position: relative;
}

.guide-step {
  width: 32px;
  height: 32px;
  background: var(--color-primary);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.9rem;
  margin-bottom: 12px;
}

.guide-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--color-text);
}

.guide-card p {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  line-height: 1.55;
}

/* ===== Safety Section ===== */
.safety-section {
  padding: 48px 0;
}

.safety-section h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 28px;
  text-align: center;
}

.safety-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 28px;
}

.safety-card {
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid var(--color-border);
}

.safety-warning {
  background: var(--color-warning-bg);
  border-color: #e8b4b0;
}

.safety-tip {
  background: var(--color-tip-bg);
  border-color: #b5d5c5;
}

.safety-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.safety-warning h3 { color: var(--color-warning); }
.safety-tip h3 { color: var(--color-tip); }

.safety-card p {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  line-height: 1.55;
}

.assumptions-box {
  background: var(--color-surface-alt);
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid var(--color-border);
}

.assumptions-box h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--color-text);
}

.assumptions-box p {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ===== FAQ Section ===== */
.faq-section {
  padding: 48px 0;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
}

.faq-section h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 28px;
  text-align: center;
}

.faq-list {
  max-width: 760px;
  margin: 0 auto;
}

.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
  overflow: hidden;
}

.faq-item summary {
  padding: 14px 20px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  color: var(--color-text);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: background var(--transition);
}

.faq-item summary::-webkit-details-marker { display: none; }

.faq-item summary::after {
  content: '+';
  font-size: 1.3rem;
  font-weight: 400;
  color: var(--color-primary);
  flex-shrink: 0;
  margin-left: 12px;
}

.faq-item[open] summary::after { content: '−'; }

.faq-item summary:hover { background: var(--color-bg); }

.faq-item p {
  padding: 0 20px 16px;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--color-primary-dark);
  color: rgba(255,255,255,0.8);
  padding: 32px 0 20px;
  margin-top: auto;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.footer-brand .logo-text { color: #fff; }
.footer-brand .logo-accent { color: #95d5b2; }

.footer-tagline {
  font-size: 0.85rem;
  margin-top: 4px;
  opacity: 0.8;
}

.footer-tagline a { color: #95d5b2; }
.footer-tagline a:hover { color: #b7e4c7; }

.footer-nav ul {
  display: flex;
  list-style: none;
  gap: 20px;
  flex-wrap: wrap;
}

.footer-nav a {
  color: rgba(255,255,255,0.7);
  font-size: 0.85rem;
  font-weight: 500;
}
.footer-nav a:hover { color: #fff; text-decoration: none; }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.15);
  padding-top: 16px;
  font-size: 0.78rem;
  opacity: 0.6;
  text-align: center;
}

/* ===== Toast ===== */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-primary-dark);
  color: #fff;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.toast[hidden] {
  display: block;
  opacity: 0;
  transform: translateX(-50%) translateY(20px);
  pointer-events: none;
}

/* ===== Print Label ===== */
.print-label {
  display: none;
}

@media print {
  body * { visibility: hidden; }
  .print-label, .print-label * { visibility: visible; }
  .print-label {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: fixed;
    top: 0; left: 0;
    width: 100%;
    height: 100%;
    background: #fff;
    z-index: 9999;
    padding: 40px;
  }
  .print-label-inner {
    border: 3px solid #2d6a4f;
    border-radius: 12px;
    padding: 32px 40px;
    text-align: center;
    max-width: 400px;
  }
  .print-label h2 {
    font-size: 1.4rem;
    color: #2d6a4f;
    margin-bottom: 8px;
  }
  .print-label .pl-weight {
    font-size: 3rem;
    font-weight: 800;
    color: #1b4332;
  }
  .print-label .pl-detail {
    font-size: 0.85rem;
    color: #6b6b6b;
    margin-top: 8px;
  }
  .print-label .pl-warning {
    font-size: 0.75rem;
    color: #c0392b;
    margin-top: 16px;
    font-weight: 600;
  }
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .estimator-layout {
    grid-template-columns: 1fr;
  }
  .reference-panel {
    position: static;
  }
  .guide-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  .header-inner { height: 54px; }
  .logo-text { font-size: 1.1rem; }
  .main-nav ul { gap: 14px; }
  .main-nav a { font-size: 0.82rem; }
  .hero-section { padding: 32px 0; }
  .hero-content h1 { font-size: 1.4rem; }
  .calculator-panel { padding: 20px; }
  .material-options { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .guide-grid { grid-template-columns: 1fr; }
  .safety-grid { grid-template-columns: 1fr; }
  .result-value { font-size: 2.4rem; }
  .result-actions { flex-direction: column; }
  .result-actions .btn { width: 100%; }
  .footer-inner { flex-direction: column; align-items: center; text-align: center; }
  .footer-nav ul { justify-content: center; }
}

@media (max-width: 400px) {
  .container { padding: 0 14px; }
  .presets { flex-direction: column; align-items: flex-start; }
}



/* Factory-injected deployment helpers. The AI owns the site design above this block. */
.ad-unit {
  width: min(100%, 720px);
  min-height: 120px;
  margin: 24px auto;
  display: block;
}

.legal-page {
  width: min(900px, calc(100% - 32px));
  margin: 40px auto;
}

.factory-fallback-nav {
  width: min(900px, calc(100% - 32px));
  margin: 24px auto 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 16px;
  align-items: center;
  font-size: 0.95rem;
}

.factory-fallback-nav a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid currentColor;
}