/* =========================================================
   iestudiantes.com — design tokens
   ========================================================= */
:root {
  --navy-950: #081831;
  --navy: #0E2346;
  --navy-700: #1A3766;
  --navy-500: #2C5191;
  --silver: #C3CBD6;
  --silver-light: #E6EAF0;
  --silver-dark: #8E9AAD;
  --silver-on-navy: #C9D2DE;
  --tint: #EDF0F5;

  --bg: #F4F6F9;
  --surface: #FFFFFF;
  --ink: #0E2346;
  --ink-muted: #4C586B;
  --muted: #4C586B;
  --border: #DCE1E8;
  --border-strong: #B7C0CD;

  --ok: #1E6A44; --ok-bg: #E7F3EC;
  --bad: #A12C2C; --bad-bg: #F8E9E9;
  --warn: #7F5300; --warn-bg: #FBF2DE;

  --cat-est: var(--navy-700); --cat-est-bg: var(--tint);
  --cat-mate: var(--navy-700); --cat-mate-bg: var(--tint);
  --cat-cien: var(--navy-700); --cat-cien-bg: var(--tint);
  --cat-conv: var(--navy-700); --cat-conv-bg: var(--tint);
  --cat-fin: var(--navy-700); --cat-fin-bg: var(--tint);
  --cat-web: var(--navy-700); --cat-web-bg: var(--tint);
  --cat-id: var(--navy-700); --cat-id-bg: var(--tint);
  --cat-util: var(--navy-700); --cat-util-bg: var(--tint);

  --radius-sm: 6px;
  --radius-md: 10px;

  --font-display: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --font-body: 'IBM Plex Sans', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-mono: 'IBM Plex Mono', 'SFMono-Regular', Menlo, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  margin: 0 0 0.4em 0;
  letter-spacing: -0.01em;
}

p { margin: 0 0 1em 0; color: var(--ink-muted); }

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}

button { font-family: inherit; cursor: pointer; }

a { color: inherit; }

:focus-visible {
  outline: 2px solid var(--cat-conv);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

/* =========================================================
   Header
   ========================================================= */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(247, 248, 250, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 32px;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  text-decoration: none;
  color: var(--ink);
  background: none;
  border: none;
  padding: 0;
  flex-shrink: 0;
}
.logo strong { font-weight: 700; color: var(--cat-mate); }
.logo svg { color: var(--ink); flex-shrink: 0; }

.main-nav {
  display: flex;
  gap: 4px;
  flex: 1;
}

.nav-link {
  background: none;
  border: none;
  color: var(--ink-muted);
  font-size: 0.9rem;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
}
.nav-link:hover { color: var(--ink); background: var(--surface); }

.header-search { flex-shrink: 0; }
.header-search input {
  width: 220px;
  padding: 8px 12px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  background: var(--surface);
  color: var(--ink);
}
.header-search input:focus { border-color: var(--cat-conv); outline: none; }

@media (max-width: 860px) {
  .main-nav { display: none; }
  .header-search input { width: 160px; }
}

/* =========================================================
   Hero
   ========================================================= */
.hero { padding: 64px 0 56px; }

.hero-inner {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 56px;
  align-items: center;
}

.hero-text h1 {
  font-size: clamp(2rem, 4vw, 2.75rem);
  line-height: 1.1;
  margin-bottom: 0.5em;
}

.hero-text p {
  font-size: 1.05rem;
  max-width: 46ch;
  margin-bottom: 1.6em;
}

.hero-search input {
  width: 100%;
  max-width: 440px;
  padding: 14px 16px;
  border: 1.5px solid var(--border-strong);
  border-radius: var(--radius-md);
  font-size: 0.98rem;
  background: var(--surface);
  color: var(--ink);
}
.hero-search input:focus { border-color: var(--cat-mate); outline: none; }

.demo-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px 22px 22px;
  box-shadow: 0 1px 2px rgba(20, 33, 61, 0.04);
}

.demo-card-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  color: var(--ink-muted);
  margin-bottom: 18px;
}

.demo-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--cat-mate);
  flex-shrink: 0;
}

.demo-label {
  display: block;
  font-size: 0.8rem;
  color: var(--ink-muted);
  margin-bottom: 6px;
}

.demo-input {
  width: 100%;
  padding: 10px 12px;
  border: 1.5px solid var(--cat-mate);
  border-radius: var(--radius-sm);
  font-size: 1.1rem;
  font-family: var(--font-mono);
  color: var(--ink);
  margin-bottom: 18px;
  background: var(--cat-mate-bg);
}
.demo-input:focus { outline: none; }

.demo-outputs { display: flex; flex-direction: column; gap: 10px; }
.demo-out-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--ink-muted);
}
.demo-out-row output {
  font-size: 1.02rem;
  color: var(--ink);
  font-weight: 500;
}

@media (max-width: 780px) {
  .hero-inner { grid-template-columns: 1fr; gap: 32px; }
}

/* =========================================================
   Category sections & tool cards
   ========================================================= */
.category-section { padding: 40px 0; }
.category-section:last-of-type { padding-bottom: 72px; }

.category-heading { margin-bottom: 24px; padding-left: 14px; border-left: 3px solid; }
.category-heading h2 { font-size: 1.4rem; margin-bottom: 0.2em; }
.category-heading p { margin: 0; font-size: 0.95rem; }

.category-heading.cat-mate { border-color: var(--cat-mate); }
.category-heading.cat-conv { border-color: var(--cat-conv); }
.category-heading.cat-fin { border-color: var(--cat-fin); }
.category-heading.cat-web { border-color: var(--cat-web); }
.category-heading.cat-id { border-color: var(--cat-id); }
.category-heading.cat-util { border-color: var(--cat-util); }

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px;
}

.tool-card {
  text-align: left;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 3px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 18px 18px 20px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  transition: border-color 0.15s ease, transform 0.1s ease;
}
.tool-card:hover { transform: translateY(-1px); }
.tool-card.cat-mate:hover, .tool-card.cat-mate:focus-visible { border-left-color: var(--cat-mate); }
.tool-card.cat-conv:hover, .tool-card.cat-conv:focus-visible { border-left-color: var(--cat-conv); }
.tool-card.cat-fin:hover, .tool-card.cat-fin:focus-visible { border-left-color: var(--cat-fin); }
.tool-card.cat-web:hover, .tool-card.cat-web:focus-visible { border-left-color: var(--cat-web); }
.tool-card.cat-id:hover, .tool-card.cat-id:focus-visible { border-left-color: var(--cat-id); }
.tool-card.cat-util:hover, .tool-card.cat-util:focus-visible { border-left-color: var(--cat-util); }

.tool-card-icon {
  width: 30px; height: 30px;
  margin-bottom: 8px;
}
.tool-card-icon svg { width: 100%; height: 100%; }
.tool-card.cat-mate .tool-card-icon { color: var(--cat-mate); }
.tool-card.cat-conv .tool-card-icon { color: var(--cat-conv); }
.tool-card.cat-fin .tool-card-icon { color: var(--cat-fin); }
.tool-card.cat-web .tool-card-icon { color: var(--cat-web); }
.tool-card.cat-id .tool-card-icon { color: var(--cat-id); }
.tool-card.cat-util .tool-card-icon { color: var(--cat-util); }

.tool-card h3 {
  font-size: 1rem;
  font-family: var(--font-body);
  font-weight: 600;
  margin: 0;
}
.tool-card p { font-size: 0.87rem; margin: 0; color: var(--ink-muted); }

.no-results {
  text-align: center;
  padding: 48px 0;
  color: var(--ink-muted);
}

/* =========================================================
   Tool views
   ========================================================= */
.tool-view { padding: 40px 0 80px; }

.back-link {
  background: none;
  border: none;
  color: var(--ink-muted);
  font-size: 0.88rem;
  padding: 6px 0;
  margin-bottom: 20px;
}
.back-link:hover { color: var(--ink); }
.back-link::before { content: '← '; }

.tool-head { padding-left: 16px; border-left: 3px solid; margin-bottom: 28px; }
.tool-head.cat-mate { border-color: var(--cat-mate); }
.tool-head.cat-conv { border-color: var(--cat-conv); }
.tool-head.cat-fin { border-color: var(--cat-fin); }
.tool-head.cat-web { border-color: var(--cat-web); }
.tool-head.cat-id { border-color: var(--cat-id); }
.tool-head.cat-util { border-color: var(--cat-util); }
.tool-head h1 { font-size: 1.7rem; }
.tool-head p { max-width: 58ch; margin: 0; }

.tool-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 28px 28px 30px;
  max-width: 720px;
}

.field-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 16px;
  margin-bottom: 8px;
}
.field-grid-narrow { grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); max-width: 420px; }

.field { display: flex; flex-direction: column; gap: 6px; margin-bottom: 16px; }
.field label { font-size: 0.83rem; color: var(--ink-muted); font-weight: 500; }

input[type="text"], input[type="number"], input[type="date"], select, textarea {
  padding: 10px 12px;
  border: 1.5px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-size: 0.98rem;
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--surface);
  width: 100%;
}
textarea { font-family: var(--font-body); resize: vertical; }
input:focus, select:focus, textarea:focus { outline: none; border-color: var(--cat-conv); }
.mono { font-family: var(--font-mono); }

.tool-note { font-size: 0.85rem; color: var(--ink-muted); margin-top: 6px; }

.results-box {
  margin-top: 8px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.result-line {
  font-size: 0.95rem;
  color: var(--ink-muted);
  margin: 0 0 8px 0;
  display: flex;
  justify-content: space-between;
  gap: 12px;
}
.result-value {
  color: var(--ink);
  font-weight: 600;
  font-size: 1rem;
}

.sub-tool { padding: 18px 0; border-bottom: 1px solid var(--border); }
.sub-tool:last-child { border-bottom: none; padding-bottom: 0; }
.sub-tool:first-child { padding-top: 0; }
.sub-tool h3 { font-size: 0.98rem; font-family: var(--font-body); font-weight: 600; margin-bottom: 12px; }

/* Multiplication table */
.mult-table {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  gap: 8px;
  margin-top: 12px;
}
.mult-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 10px;
  background: var(--cat-mate-bg);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.92rem;
}
.mult-row span:last-child { font-weight: 600; }

/* Color tool */
.color-layout { display: flex; gap: 24px; align-items: flex-start; flex-wrap: wrap; }
.color-swatch {
  width: 96px; height: 96px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  flex-shrink: 0;
}
.color-layout .field-grid { flex: 1; min-width: 220px; }

/* Password tool */
.pass-output-row {
  display: flex;
  gap: 10px;
  margin-bottom: 22px;
}
.pass-output {
  flex: 1;
  padding: 14px 16px;
  background: var(--cat-web-bg);
  border: 1.5px solid var(--cat-web);
  border-radius: var(--radius-sm);
  font-size: 1.05rem;
  word-break: break-all;
}
.checkbox-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 24px;
  margin: 14px 0 22px;
  font-size: 0.9rem;
  color: var(--ink-muted);
}
.checkbox-row label { display: flex; align-items: center; gap: 7px; }
input[type="range"] { width: 100%; accent-color: var(--cat-web); margin-top: 6px; }
input[type="checkbox"] { accent-color: var(--cat-web); width: 16px; height: 16px; }

.btn-primary, .btn-secondary {
  border-radius: var(--radius-sm);
  padding: 11px 18px;
  font-size: 0.92rem;
  font-weight: 500;
  border: 1.5px solid transparent;
}
.btn-primary { background: var(--ink); color: #fff; }
.btn-primary:hover { background: var(--navy-700); }
.btn-secondary { background: var(--surface); color: var(--ink); border-color: var(--border-strong); }
.btn-secondary:hover { border-color: var(--ink); }

/* Base64 */
.b64-buttons { display: flex; gap: 10px; margin: 4px 0 20px; flex-wrap: wrap; }

/* Text counter */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
  gap: 12px;
  margin-top: 18px;
}
.stat-box {
  background: var(--cat-web-bg);
  border-radius: var(--radius-sm);
  padding: 14px 12px;
  text-align: center;
}
.stat-value { display: block; font-size: 1.4rem; font-weight: 600; color: var(--cat-web); margin-bottom: 2px; }
.stat-box span { font-size: 0.78rem; color: var(--ink-muted); }

/* Word frequency */
.checkbox-inline {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.88rem;
  color: var(--ink-muted);
  margin: 4px 0 18px;
}
.freq-list { display: flex; flex-direction: column; gap: 8px; }
.freq-row {
  display: grid;
  grid-template-columns: 100px 1fr 84px;
  align-items: center;
  gap: 12px;
  font-size: 0.87rem;
}
.freq-word {
  font-weight: 600;
  color: var(--ink);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.freq-bar-track {
  background: var(--cat-web-bg);
  border-radius: 4px;
  height: 10px;
  overflow: hidden;
}
.freq-bar { background: var(--cat-web); height: 100%; border-radius: 4px; }
.freq-count { color: var(--ink-muted); text-align: right; }

/* Fractions */
.fraction-row {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  margin-bottom: 8px;
}
.fraction-input, .fraction-result {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}
.fraction-input input {
  width: 64px;
  text-align: center;
  padding: 8px 6px;
}
.fraction-bar {
  width: 64px;
  height: 2px;
  background: var(--ink);
}
.fraction-result .fraction-bar { background: var(--cat-mate); }
.fraction-result output {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--cat-mate);
  min-width: 40px;
  text-align: center;
}
.fraction-eq { font-size: 1.3rem; color: var(--ink-muted); }
#fr-op { width: auto; padding: 8px 10px; }

/* Case converter */
.case-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 4px 0 18px;
}

/* Stopwatch / Timer */
.stopwatch-display {
  font-family: var(--font-mono);
  font-size: 2.6rem;
  font-weight: 600;
  text-align: center;
  color: var(--cat-util);
  background: var(--cat-util-bg);
  border-radius: var(--radius-md);
  padding: 28px 16px;
  margin-bottom: 20px;
  letter-spacing: 0.02em;
}
.stopwatch-buttons {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 18px;
}
.lap-list {
  list-style: none;
  margin: 0;
  padding: 0;
  max-height: 220px;
  overflow-y: auto;
}
.lap-list li {
  display: flex;
  justify-content: space-between;
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 0.9rem;
}
.lap-list li:first-child { border-top: 1px solid var(--border); }
#tm-inputs { justify-content: center; margin: 0 auto 4px; }

/* Identity validator */
.id-result {
  margin: 16px 0;
  padding: 16px 18px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 1.02rem;
  display: none;
}
.id-result.valid { display: block; background: var(--cat-util-bg); color: var(--cat-util); border: 1.5px solid var(--cat-util); }
.id-result.invalid { display: block; background: var(--cat-id-bg); color: var(--cat-id); border: 1.5px solid var(--cat-id); }
.id-result.partial { display: block; background: var(--cat-fin-bg); color: var(--cat-fin); border: 1.5px solid var(--cat-fin); }

/* File input (PDF reader) */
input[type="file"] {
  font-size: 0.85rem;
  color: var(--ink-muted);
  padding: 0;
  border: none;
}
input[type="file"]::file-selector-button {
  margin-right: 12px;
  padding: 9px 14px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--border-strong);
  background: var(--surface);
  color: var(--ink);
  font-family: inherit;
  font-size: 0.85rem;
  cursor: pointer;
}
input[type="file"]::file-selector-button:hover { border-color: var(--ink); }

/* =========================================================
   Footer
   ========================================================= */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--surface);
  padding: 48px 0 0;
}
.footer-inner {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 48px;
  padding-bottom: 32px;
}
.footer-inner > div:first-child p { font-size: 0.88rem; max-width: 34ch; margin-top: 12px; }
.logo-footer { pointer-events: none; }

.footer-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 24px;
}
.footer-links h4 { font-size: 0.8rem; text-transform: none; color: var(--ink); margin: 0 0 10px; font-family: var(--font-body); font-weight: 600; }
.footer-links button {
  display: block;
  background: none;
  border: none;
  color: var(--ink-muted);
  font-size: 0.85rem;
  padding: 5px 0;
  text-align: left;
  width: 100%;
}
.footer-links button:hover { color: var(--cat-mate); }

.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 16px 0 20px;
}
.footer-bottom p { font-size: 0.78rem; margin: 0; color: var(--ink-muted); }

@media (max-width: 780px) {
  .footer-inner { grid-template-columns: 1fr; }
  .footer-links { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 500px) {
  .header-inner { gap: 12px; }
  .header-search input { width: 120px; }
  .tool-panel { padding: 20px 18px 22px; }
}


/* QA/accessibility refinements */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
[hidden] { display: none !important; }
button, input, select, textarea { -webkit-tap-highlight-color: transparent; }
@media (max-width: 860px) {
  .site-header { position: sticky; }
  .header-inner { min-height: 64px; height: auto; padding-top: 8px; padding-bottom: 8px; }
  .header-search { flex: 1; min-width: 0; }
  .header-search input { width: 100%; }
}
@media (max-width: 500px) {
  .container { padding-left: 16px; padding-right: 16px; }
  .hero { padding-top: 40px; }
  .tool-grid { grid-template-columns: 1fr; }
  .result-line { align-items: flex-start; flex-direction: column; gap: 2px; }
}


/* v2.1 static SEO routes */
.tool-card { text-decoration: none; color: inherit; }
.footer-links a { display:block; background:none; border:none; padding:3px 0; color:var(--ink-muted); text-decoration:none; font-size:.84rem; }
.footer-links a:hover { color:var(--ink); }
.nav-link-static { text-decoration:none; display:inline-flex; align-items:center; }
.footer-bottom-inner { display:flex; justify-content:space-between; gap:20px; align-items:center; flex-wrap:wrap; }
.legal-links { display:flex; gap:16px; flex-wrap:wrap; }
.legal-links a { color:var(--ink-muted); text-decoration:none; font-size:.84rem; }
.legal-links a:hover { color:var(--ink); text-decoration:underline; }
.tool-seo-intro { margin-top:12px !important; }
@media (max-width: 640px) { .tool-panel,.static-content{padding:22px 18px}.legal-links{gap:12px} }

/* v2.2 footer + standalone page refinements */
.copyright { margin: 0; font-size: .82rem; color: var(--ink-muted); }
.footer-bottom-inner { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: 12px 24px; }
.sr-only { position:absolute; width:1px; height:1px; padding:0; margin:-1px; overflow:hidden; clip:rect(0,0,0,0); white-space:nowrap; border:0; }
@media (max-width: 640px) { .footer-bottom-inner { align-items:flex-start; flex-direction:column; } .copyright { order: 3; } }

/* SEO and reference content */
.seo-content { padding: 0 0 64px; }
.seo-content-inner { max-width: 760px; }
.seo-content h2 { font-size: 1.25rem; margin: 2rem 0 .55rem; }
.seo-content h3 { font-size: 1rem; margin: 1.4rem 0 .45rem; }
.seo-content p { max-width: 72ch; }
.reference-section { padding: 24px 0 72px; }
.reference-links { display:grid; grid-template-columns:repeat(auto-fill,minmax(130px,1fr)); gap:10px; }
.reference-links a { display:block; padding:10px 12px; border:1px solid var(--border); border-radius:var(--radius-sm); background:var(--surface); text-decoration:none; color:var(--ink); }
.reference-links a:hover { border-color:var(--cat-mate); }
.reference-table { width:100%; border-collapse:collapse; margin:22px 0; }
.reference-table th,.reference-table td { padding:9px 10px; border-bottom:1px solid var(--border); text-align:left; }
.reference-table th { font-weight:600; background:var(--cat-mate-bg); }
.print-actions { display:flex; gap:10px; margin:16px 0 22px; }
@media print { .site-header,.site-footer,.print-actions,.tool-panel { display:none !important; } .reference-table { font-size:12pt; } .static-page,.tool-view { padding:0; } }


/* Reference tables on SEO pages */
.tax-reference { margin-top: 28px; }
.tax-reference h2 { margin-top: 0; }
.tax-reference table { width: 100%; border-collapse: collapse; margin-top: 14px; font-size: 0.9rem; background: var(--surface); }
.tax-reference th, .tax-reference td { padding: 10px 12px; border: 1px solid var(--border); text-align: left; vertical-align: top; }
.tax-reference th { font-weight: 600; color: var(--ink); background: var(--bg); }
.tax-reference td { color: var(--ink-muted); }
@media (max-width: 620px) { .tax-reference { overflow-x: auto; } .tax-reference table { min-width: 620px; } }


.practice-box{margin:2rem 0;padding:1.25rem;border:1px solid var(--border);border-radius:var(--radius-md);background:var(--surface)}
.practice-question{font-size:1.6rem;margin:1rem 0}.practice-controls{display:flex;gap:.6rem;flex-wrap:wrap;align-items:center}.practice-controls input{width:9rem}.btn-secondary{border:1px solid var(--border);background:var(--surface);color:var(--ink);padding:.7rem 1rem;border-radius:10px;font:inherit;cursor:pointer}.small-note{font-size:.92rem;color:var(--muted)}


/* =========================================================
   iestudiantes — tema azul marino y plata
   (capa final: sobrescribe los estilos heredados)
   ========================================================= */
body { background: var(--bg); }
h1, h2 { font-family: var(--font-display); font-weight: 600; letter-spacing: -0.005em; }
h1 { line-height: 1.12; }
a { text-underline-offset: 0.18em; }
:focus-visible { outline: 2px solid var(--navy-500); outline-offset: 2px; }

/* Header */
.site-header {
  background: var(--navy);
  border-bottom: 0;
  backdrop-filter: none;
}
.site-header::after {
  content: "";
  display: block;
  height: 2px;
  background: linear-gradient(90deg, var(--silver-dark), var(--silver-light) 50%, var(--silver-dark));
}
.header-inner { gap: 28px; }
.logo { color: #fff; gap: 10px; }
.logo svg { color: var(--silver); }
.wordmark { font-family: var(--font-display); font-size: 1.32rem; font-weight: 600; letter-spacing: -0.01em; color: #fff; line-height: 1; }
.wm-i { color: var(--silver); }
.main-nav { gap: 2px; }
.nav-link { color: var(--silver-on-navy); font-size: 0.88rem; padding: 8px 10px; text-decoration: none; white-space: nowrap; }
.nav-link:hover, .nav-link:focus-visible { color: #fff; background: rgba(255, 255, 255, 0.08); }
.header-search input {
  width: 210px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(197, 206, 219, 0.45);
  color: #fff;
}
.header-search input::placeholder { color: #A9B4C4; }
.header-search input:focus { border-color: var(--silver); background: rgba(255, 255, 255, 0.14); }

@media (max-width: 1100px) {
  .header-inner { flex-wrap: wrap; height: auto; min-height: 64px; row-gap: 0; padding-top: 10px; }
  .header-search { flex: 1; display: flex; justify-content: flex-end; }
  .main-nav {
    display: flex !important;
    order: 3;
    flex: 0 0 100%;
    overflow-x: auto;
    scrollbar-width: none;
    margin: 6px -10px 0;
    padding-bottom: 6px;
  }
  .main-nav::-webkit-scrollbar { display: none; }
}
@media (max-width: 600px) {
  .header-search input { width: 100%; max-width: 220px; }
  .wordmark { font-size: 1.18rem; }
}

/* Hero */
.hero {
  background: var(--navy);
  color: #fff;
  padding: 56px 0 64px;
  border-bottom: 1px solid var(--silver-dark);
}
.hero-text h1 { color: #fff; font-size: clamp(2.1rem, 4.4vw, 3.05rem); max-width: 18ch; }
.hero-text p { color: var(--silver-on-navy); font-size: 1.08rem; }
.hero-search input { border: 1.5px solid transparent; }
.hero-search input:focus { border-color: var(--silver); }
.hero-popular { margin: 18px 0 0; font-size: 0.9rem; color: #A9B4C4; }
.hero-popular a { color: #fff; margin-right: 14px; white-space: nowrap; display: inline-block; text-decoration-color: var(--silver-dark); }
.hero-popular a:hover { text-decoration-color: #fff; }

.demo-card { border: 0; border-top: 3px solid var(--silver); box-shadow: 0 18px 40px rgba(4, 14, 32, 0.35); color: var(--ink); }
.demo-card-head { font-size: 0.95rem; color: var(--ink); font-weight: 600; margin-bottom: 14px; }
.demo-fields { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; align-items: end; }
.demo-fields .field { margin-bottom: 0; }
.demo-fields input { font-family: var(--font-mono); }
.demo-answer { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; margin-top: 18px; padding: 14px 16px; background: var(--tint); border-radius: var(--radius-sm); }
.demo-answer span { font-size: 0.9rem; color: var(--ink-muted); }
.demo-answer output { font-size: 1.9rem; font-weight: 600; color: var(--navy); }
.demo-msg { font-size: 0.86rem; margin: 10px 0 12px; min-height: 2.6em; }
.demo-link { font-size: 0.88rem; color: var(--navy-700); font-weight: 500; }
@media (max-width: 520px) { .demo-fields { grid-template-columns: 1fr; } }

/* Categorías y tarjetas */
.category-section { padding: 44px 0 8px; }
.category-heading { border-left: 3px solid var(--navy) !important; }
.category-heading h2 { font-size: 1.55rem; color: var(--navy); }
.tool-card {
  border: 1px solid var(--border);
  border-left: 3px solid var(--silver);
  border-radius: var(--radius-sm);
  transition: border-color 0.15s ease;
}
.tool-card:hover { transform: none; border-color: var(--border-strong); }
.tool-card:hover, .tool-card:focus-visible { border-left-color: var(--navy) !important; }
.tool-card-icon { color: var(--navy-700) !important; }
.tool-card h3 { color: var(--navy); }

/* Vistas de herramienta */
.tool-head { border-left: 3px solid var(--navy) !important; }
.tool-head h1 { color: var(--navy); font-size: clamp(1.7rem, 3vw, 2.1rem); }
.back-link { text-decoration: none; }
.tool-panel { border-top: 3px solid var(--silver); }
input:focus, select:focus, textarea:focus { border-color: var(--navy-500); }
input:disabled { background: var(--tint); color: var(--ink-muted); }
.btn-primary { background: var(--navy); color: #fff; border-color: var(--navy); }
.btn-primary:hover { background: var(--navy-700); }
.btn-secondary { background: var(--surface); color: var(--navy); border: 1.5px solid var(--border-strong); border-radius: var(--radius-sm); padding: 10px 16px; }
.btn-secondary:hover { border-color: var(--navy); }
.result-value { color: var(--navy); }
.result-key { font-size: 1.02rem; color: var(--ink); }
.result-key .result-value { font-size: 1.35rem; }
.spaced { margin-top: 18px; }
.label-like { font-size: 0.83rem; color: var(--ink-muted); font-weight: 500; }

.stopwatch-display { color: var(--navy); background: var(--tint); }
.id-result.valid { background: var(--ok-bg); color: var(--ok); border-color: var(--ok); }
.id-result.invalid { background: var(--bad-bg); color: var(--bad); border-color: var(--bad); }
.id-result.partial { background: var(--warn-bg); color: var(--warn); border-color: var(--warn); }
.mult-row { background: var(--tint); }

/* Mensajes de estado */
.status-line { margin: 10px 0 0; font-size: 0.92rem; color: var(--ink-muted); min-height: 1.4em; }
.status-line.is-ok, .status-line.is-bad, .status-line.is-warn, .status-line.is-info { padding: 10px 12px; border-radius: var(--radius-sm); border-left: 3px solid; }
.status-line.is-ok { background: var(--ok-bg); color: var(--ok); }
.status-line.is-bad { background: var(--bad-bg); color: var(--bad); }
.status-line.is-warn { background: var(--warn-bg); color: var(--warn); }
.status-line.is-info { background: var(--tint); color: var(--navy); }

/* Escala + filas de notas */
.scale-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); align-items: end; }
.scale-grid .field-wide { grid-column: 1 / -1; }
.scale-grid .field-wide select { max-width: 520px; }
.grade-rows { display: flex; flex-direction: column; gap: 4px; margin: 6px 0 10px; }
.grade-row { display: grid; grid-template-columns: repeat(var(--cols, 2), minmax(0, 1fr)) 40px; gap: 12px; align-items: end; }
.grade-rows-3 .grade-row { grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr) minmax(0, 1fr) 40px; }
.grade-rows-3.has-output .grade-row { grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr) minmax(0, 0.8fr) 72px 40px; }
.grade-row .field { margin-bottom: 8px; }
.row-remove {
  height: 42px; margin-bottom: 8px;
  border: 1.5px solid var(--border-strong); background: var(--surface); color: var(--ink-muted);
  border-radius: var(--radius-sm); font-size: 1.2rem; line-height: 1;
}
.row-remove:hover { border-color: var(--bad); color: var(--bad); }
.row-output { align-self: center; margin-top: 14px; font-size: 0.85rem; color: var(--navy); font-weight: 600; white-space: nowrap; }
@media (max-width: 520px) {
  .grade-rows-3 .grade-row, .grade-rows-3.has-output .grade-row { grid-template-columns: 1fr 1fr 40px; }
  .grade-rows-3 .grade-row .field-name { grid-column: 1 / -1; }
  .grade-rows-3.has-output .row-output { grid-column: 1 / 3; margin-top: 0; }
  .grade-row { padding-bottom: 8px; border-bottom: 1px solid var(--border); }
}

/* Resultados en dos columnas */
@media (min-width: 640px) {
  .results-columns { display: grid; grid-template-columns: 1fr 1fr; column-gap: 28px; }
}

/* Calculadora científica */
.calc-screen { background: var(--navy); border-radius: var(--radius-md); padding: 14px 16px 16px; display: flex; flex-direction: column; gap: 6px; }
.calc-input { background: transparent !important; border: 0 !important; color: #fff !important; font-size: 1.15rem !important; padding: 4px 0 !important; }
.calc-input::placeholder { color: #8E9AAD; }
.calc-result { text-align: right; color: var(--silver-light); font-size: 2rem; font-weight: 600; word-break: break-all; }
.calc-error { color: var(--bad); min-height: 1.3em; }
.calc-options { display: flex; align-items: center; gap: 10px; margin: 4px 0 14px; font-size: 0.88rem; color: var(--ink-muted); }
.calc-options select { width: auto; padding: 6px 10px; }
.calc-keys { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.calc-keys button {
  padding: 12px 4px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: var(--tint); color: var(--navy);
  font-family: var(--font-mono); font-size: 0.95rem;
}
.calc-keys button:hover { border-color: var(--navy-500); }
.calc-keys .key-num { background: var(--surface); font-weight: 600; }
.calc-keys .key-eval { background: var(--navy); color: #fff; border-color: var(--navy); }
.calc-history { list-style: none; margin: 0; padding: 0; }
.calc-history:empty::after { content: "Las operaciones que calcules aparecerán aquí."; font-size: 0.88rem; color: var(--ink-muted); }
.history-item { width: 100%; display: flex; justify-content: space-between; gap: 12px; background: none; border: 0; border-bottom: 1px solid var(--border); padding: 8px 2px; font-family: var(--font-mono); font-size: 0.88rem; color: var(--ink-muted); text-align: left; }
.history-item span:last-child { color: var(--navy); font-weight: 600; }
.history-item:hover { color: var(--ink); }

/* Regla de tres */
.rule3 { display: flex; flex-direction: column; gap: 4px; margin-top: 8px; }
.rule3-row { display: grid; grid-template-columns: 1fr 32px 1fr; align-items: end; gap: 8px; max-width: 460px; }
.rule3-arrow { text-align: center; padding-bottom: 26px; color: var(--silver-dark); font-size: 1.2rem; }
.rule3-x { display: block; padding: 10px 12px; border: 1.5px solid var(--navy); border-radius: var(--radius-sm); background: var(--tint); font-weight: 600; color: var(--navy); min-height: 44px; margin-bottom: 16px; }

/* Sistemas de ecuaciones */
.eq-grid { display: flex; flex-direction: column; gap: 10px; margin: 6px 0 14px; overflow-x: auto; }
.eq-row { display: flex; align-items: center; gap: 8px; min-width: max-content; }
.eq-row input { width: 78px; text-align: center; padding: 8px 6px; }
.eq-var, .eq-sign { font-family: var(--font-mono); color: var(--navy); font-weight: 600; }

/* Factores */
.factor-list { list-style: none; margin: 0; padding: 0; }
.factor-list li { display: flex; justify-content: space-between; gap: 16px; padding: 8px 0; border-bottom: 1px solid var(--border); font-size: 0.92rem; }
.factor-list li span:last-child { color: var(--navy); font-weight: 600; text-align: right; }

/* Escala de notas */
.score-table { grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); max-height: 420px; overflow-y: auto; padding-right: 4px; }
.score-table .mult-row { background: var(--bad-bg); }
.score-table .mult-row.is-pass { background: var(--tint); }

/* Pomodoro */
.pomo-phase { text-align: center; font-weight: 600; color: var(--navy); margin-bottom: 8px; }
.pomo-display { font-size: clamp(3rem, 10vw, 4.4rem); }
.pomo-display[data-phase="short"], .pomo-display[data-phase="long"] { background: var(--navy); color: #fff; }

/* Herramientas relacionadas */
.related-tools { padding: 0 0 64px; }
.related-tools h2 { font-size: 1.25rem; margin-bottom: 14px; }
.related-list { display: flex; flex-wrap: wrap; gap: 8px; max-width: 760px; }
.related-list a { padding: 8px 12px; border: 1px solid var(--border-strong); border-radius: 999px; background: var(--surface); color: var(--navy); text-decoration: none; font-size: 0.9rem; }
.related-list a:hover { border-color: var(--navy); }

/* Footer */
.site-footer { background: var(--navy-950); border-top: 2px solid var(--silver-dark); color: var(--silver-on-navy); padding-top: 48px; }
.footer-inner { grid-template-columns: 1fr 3fr; }
.footer-brand p { color: #A9B4C4 !important; font-size: 0.88rem; max-width: 34ch; margin-top: 14px; }
.logo-footer .wordmark { font-size: 1.3rem; }
.footer-links { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); }
.footer-links h4 { color: #fff !important; font-size: 0.86rem !important; }
.footer-links a { color: var(--silver-on-navy) !important; }
.footer-links a:hover { color: #fff !important; text-decoration: underline; }
.footer-bottom { border-top: 1px solid rgba(197, 206, 219, 0.2); padding: 18px 0 22px; }
.legal-links a { color: var(--silver-on-navy) !important; }
.legal-links a:hover { color: #fff !important; }
.copyright, .footer-bottom p { color: #A9B4C4 !important; }
@media (max-width: 780px) { .footer-inner { grid-template-columns: 1fr; } }

/* Páginas de texto */
.static-content { border-top: 3px solid var(--silver) !important; }
.static-content h1 { color: var(--navy); }
.seo-content h2 { color: var(--navy); }
.faq-item h3 { font-family: var(--font-body); font-size: 1rem; color: var(--ink); }
.no-results { padding-bottom: 72px; }