@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500&family=IBM+Plex+Sans:wght@400;500;600&display=swap');

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

:root {
  --black: #1A1A1A;
  --white: #FFFFFF;
  --surface: #F4F4F2;
  --border: #DDDDD8;
  --muted: #6B6B67;
  --accent: #D4570A;
  --accent-dark: #A83F05;
  --text: #1A1A1A;
  --mono: 'IBM Plex Mono', monospace;
  --sans: 'IBM Plex Sans', sans-serif;
}

body {
  font-family: var(--sans);
  color: var(--text);
  background: var(--white);
  font-size: 16px;
  line-height: 1.6;
}

/* NAV */
nav {
  background: var(--black);
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-logo {
  font-family: var(--mono);
  font-size: 14px;
  font-weight: 500;
  color: var(--white);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.nav-logo span {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  font-family: var(--mono);
  font-size: 12px;
  color: #AAAAAA;
  text-decoration: none;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: color 0.15s;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--white);
}

/* HERO */
.hero {
  background: var(--black);
  padding: 5rem 2rem 4rem;
  border-bottom: 3px solid var(--accent);
}

.hero-inner {
  max-width: 860px;
  margin: 0 auto;
}

.hero-eyebrow {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 1.25rem;
}

.hero h1 {
  font-family: var(--sans);
  font-size: 2.5rem;
  font-weight: 600;
  color: var(--white);
  line-height: 1.2;
  margin-bottom: 1.25rem;
  max-width: 600px;
}

.hero p {
  font-size: 1rem;
  color: #AAAAAA;
  max-width: 520px;
  line-height: 1.7;
}

/* TOOLS GRID */
.tools-section {
  padding: 4rem 2rem;
  max-width: 960px;
  margin: 0 auto;
}

.section-label {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 2rem;
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
}

.tool-card {
  background: var(--white);
  padding: 2rem;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: background 0.15s;
  position: relative;
}

.tool-card:hover {
  background: var(--surface);
}

.tool-card::after {
  content: '';
  display: block;
  width: 32px;
  height: 2px;
  background: var(--accent);
  margin-top: 1.5rem;
  transition: width 0.2s;
}

.tool-card:hover::after {
  width: 56px;
}

.tool-tag {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
  display: block;
}

.tool-card h2 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  line-height: 1.3;
}

.tool-card p {
  font-size: 0.875rem;
  color: var(--muted);
  line-height: 1.6;
}

.tool-arrow {
  position: absolute;
  top: 2rem;
  right: 2rem;
  font-size: 1.25rem;
  color: var(--border);
  transition: color 0.15s, transform 0.15s;
}

.tool-card:hover .tool-arrow {
  color: var(--accent);
  transform: translateX(3px);
}

/* FEATURES */
.features {
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 3rem 2rem;
}

.features-inner {
  max-width: 960px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
}

.feature {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.feature-label {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.feature-value {
  font-size: 0.9rem;
  color: var(--text);
  font-weight: 500;
}

/* CALCULATOR PAGE */
.calc-header {
  background: var(--black);
  padding: 3rem 2rem 2.5rem;
  border-bottom: 3px solid var(--accent);
}

.calc-header-inner {
  max-width: 860px;
  margin: 0 auto;
}

.calc-header .breadcrumb {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: 0.08em;
  margin-bottom: 1rem;
}

.calc-header .breadcrumb a {
  color: #888;
  text-decoration: none;
}

.calc-header .breadcrumb a:hover { color: var(--white); }

.calc-header h1 {
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 0.5rem;
}

.calc-header p {
  font-size: 0.9rem;
  color: #888;
  max-width: 560px;
}

.calc-body {
  max-width: 860px;
  margin: 0 auto;
  padding: 2.5rem 2rem 4rem;
}

/* FORM ELEMENTS */
.field-group {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1rem;
}

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

label {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

input[type=number], select {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--border);
  border-radius: 3px;
  font-family: var(--sans);
  font-size: 14px;
  color: var(--text);
  background: var(--white);
  appearance: none;
  transition: border-color 0.15s;
}

input[type=number]:focus, select:focus {
  outline: none;
  border-color: var(--accent);
}

select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%236B6B67' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
  cursor: pointer;
}

.opt-block {
  border: 1px solid var(--border);
  border-radius: 3px;
  margin-bottom: 1rem;
  overflow: hidden;
}

.opt-block-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  cursor: pointer;
  background: var(--surface);
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text);
  user-select: none;
}

.opt-block-header input[type=checkbox] {
  width: auto;
  accent-color: var(--accent);
}

.opt-block-body {
  padding: 14px;
  border-top: 1px solid var(--border);
  display: none;
}

.opt-block-body.visible {
  display: block;
}

.slider-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 10px;
}

input[type=range] {
  flex: 1;
  accent-color: var(--accent);
  height: 4px;
}

.slider-val {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 500;
  min-width: 44px;
  color: var(--text);
}

.derived-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-top: 10px;
}

.derived-item {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 8px 12px;
}

.derived-label {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 2px;
}

.derived-val {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 500;
  color: var(--text);
}

.section-divider {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin: 1.5rem 0 0.75rem;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--border);
}

.calc-btn {
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: var(--white);
  border: none;
  border-radius: 3px;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  cursor: pointer;
  margin-top: 1.25rem;
  transition: background 0.15s;
}

.calc-btn:hover { background: var(--accent-dark); }

/* RESULTS */
.results-block {
  margin-top: 2rem;
  border: 1px solid var(--border);
  border-radius: 3px;
  overflow: hidden;
  display: none;
}

.results-block.visible { display: block; }

.results-header {
  background: var(--black);
  padding: 12px 16px;
  font-family: var(--mono);
  font-size: 11px;
  color: #888;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.results-body { padding: 1.25rem; }

.results-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
  margin-bottom: 1.25rem;
}

.results-table th {
  text-align: left;
  font-family: var(--mono);
  font-size: 10px;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0 8px 8px 0;
  border-bottom: 1px solid var(--border);
}

.results-table td {
  padding: 8px 8px 8px 0;
  border-bottom: 1px solid var(--border);
  color: var(--text);
}

.results-table tr:last-child td {
  border-bottom: none;
  font-weight: 600;
}

.step-num {
  display: inline-block;
  font-family: var(--mono);
  font-size: 10px;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 1px 6px;
  border-radius: 2px;
  margin-right: 6px;
  color: var(--muted);
}

.totals-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  margin-bottom: 1rem;
}

.total-item {
  background: var(--surface);
  padding: 14px 16px;
}

.total-label {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 4px;
}

.total-val {
  font-family: var(--mono);
  font-size: 22px;
  font-weight: 500;
  color: var(--text);
}

.total-unit {
  font-size: 11px;
  color: var(--muted);
  margin-left: 3px;
}

.flow-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  margin-bottom: 1rem;
}

.alert {
  padding: 10px 14px;
  border-radius: 3px;
  font-size: 12px;
  margin-bottom: 8px;
  border-left: 3px solid;
  font-family: var(--sans);
  line-height: 1.5;
}

.alert-ok { background: #F0FAF4; border-color: #2E7D52; color: #1A4D33; }
.alert-warn { background: #FFF8EC; border-color: #C47B0A; color: #6B4200; }
.alert-danger { background: #FEF1F0; border-color: #C0392B; color: #6B1A14; }
.alert-info { background: #EEF4FF; border-color: #2563EB; color: #1A3A7A; }

/* FOOTER */
footer {
  background: var(--black);
  padding: 2rem;
  text-align: center;
  font-family: var(--mono);
  font-size: 11px;
  color: #555;
  letter-spacing: 0.05em;
  border-top: 1px solid #2A2A2A;
}

footer a { color: #777; text-decoration: none; }
footer a:hover { color: var(--white); }

/* RESPONSIVE */
@media (max-width: 640px) {
  .field-group { grid-template-columns: 1fr; }
  .totals-grid, .flow-grid { grid-template-columns: 1fr 1fr; }
  .hero h1 { font-size: 1.75rem; }
  .nav-links { display: none; }
}

/* AD BANNERS */
.ad-banner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0;
  text-align: center;
  overflow: hidden;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.06em;
}

.ad-banner-top {
  margin: 0 0 2rem;
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-banner-mid {
  margin: 1.5rem 0;
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-banner-results {
  margin: 1rem 0;
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-placeholder {
  padding: 1rem;
  width: 100%;
}

.ad-placeholder span {
  display: block;
  color: var(--border);
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/* BLOG */
.page-header {
  background: var(--black);
  padding: 3rem 2rem 2.5rem;
  border-bottom: 3px solid var(--accent);
}

.page-header-inner {
  max-width: 860px;
  margin: 0 auto;
}

.page-header h1 {
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--white);
  margin-bottom: 0.5rem;
}

.page-header p {
  font-size: 0.9rem;
  color: #888;
  max-width: 560px;
}

.page-body {
  max-width: 860px;
  margin: 0 auto;
  padding: 2.5rem 2rem 4rem;
}

.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  margin-top: 1.5rem;
}

.blog-card {
  background: var(--white);
  padding: 1.75rem;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: background 0.15s;
}

.blog-card:hover { background: var(--surface); }

.blog-meta {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.blog-card h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.6rem;
  line-height: 1.35;
}

.blog-card p {
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.6;
}

/* ARTICLE */
.article-body {
  max-width: 720px;
  margin: 0 auto;
  padding: 2.5rem 2rem 4rem;
}

.article-body h2 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 2rem 0 0.75rem;
}

.article-body h3 {
  font-size: 1rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
  color: var(--muted);
}

.article-body p {
  font-size: 0.95rem;
  line-height: 1.75;
  margin-bottom: 1rem;
  color: #2A2A2A;
}

.article-body ul {
  margin: 0.75rem 0 1rem 1.25rem;
  font-size: 0.95rem;
  line-height: 1.75;
  color: #2A2A2A;
}

.article-body li { margin-bottom: 0.4rem; }

.article-cta {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 3px;
  padding: 1.25rem 1.5rem;
  margin: 2rem 0;
}

.article-cta p {
  margin: 0 0 0.75rem;
  font-size: 0.9rem;
  color: var(--muted);
}

.article-cta a {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.article-cta a:hover { color: var(--accent-dark); }

/* RESOURCES */
.resources-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.resource-group h3 {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1rem;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--border);
}

.resource-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.resource-list li {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.resource-list a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text);
  text-decoration: none;
}

.resource-list a:hover { color: var(--accent); }

.resource-list span {
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.4;
}