/* =========================================================
   Zengineering Shared Brand Stylesheet
   Applies to: index.html + all tool and article pages
   ========================================================= */

/* ---------------------------------------------------------------------------------- 
   Design tokens
   ----------------------------------------------------------------------------------  */

   :root {
    /* Brand palette */
    --zen-navy: #0D2B45;
    --zen-navy-mid: #1A4060;
    --zen-teal: #1FA78A;
    --zen-teal-dark: #178870;
    --zen-slate: #5B6B73;
    --zen-silver: #A7B3B8;
    --zen-offwhite: #F2F5F7;
  
    /* Semantic surfaces (light mode) */
    --color-bg: #F2F5F7;
    --color-surface: #FFFFFF;
    --color-surface-2: #EEF2F5;
    --color-border: #C8D4DA;
    --color-divider: #D5DFE4;
  
    /* Text */
    --color-text: #0D2B45;
    --color-text-muted: #5B6B73;
    --color-text-faint: #A7B3B8;
  
    /* Accents */
    --accent: #1FA78A;
    --accent-b: #0984e3;
    --success: #00b894;
    --warning: #f1c40f;
    --danger: #d63031;
    --purple: #6c5ce7;
  
    /* Typography */
    --font-body: "Inter", -apple-system, system-ui, sans-serif;
    --font-sans: var(--font-body);
  
    /* Spacing scale */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
  
    /* Fluid type scale */
    --text-xs: clamp(0.75rem, 0.70rem + 0.25vw, 0.875rem);
    --text-sm: clamp(0.875rem, 0.80rem + 0.35vw, 1rem);
    --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
    --text-lg: clamp(1.125rem, 1.0rem + 0.75vw, 1.5rem);
    --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
    --text-2xl: clamp(2rem, 1.2rem + 2.5vw, 3.5rem);
    --text-hero: clamp(2.25rem, 1rem + 4vw, 3.75rem);
  
    /* Radius & shadow */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
  
    --shadow-sm: 0 1px 3px rgba(13, 43, 69, 0.08);
    --shadow-md: 0 4px 16px rgba(13, 43, 69, 0.10);
    --shadow-lg: 0 12px 40px rgba(13, 43, 69, 0.14);
  
    --transition-fast: 150ms cubic-bezier(0.16, 1, 0.3, 1);
    --transition: 180ms cubic-bezier(0.16, 1, 0.3, 1);
    
    /* tooltip */
    --zen-tooltip-bg: #353b48;
    --zen-tooltip-text: #fff;
    --zen-tooltip-font: 12px;
    --zen-tooltip-max-width: 260px;
    --zen-tooltip-arrow-color: #353b48;
  }
  
  /* Shorthand alias tokens used by tool pages */
  :root {
    --primary: var(--zen-navy);
    --bg: var(--zen-offwhite);
    --card-bg: #FFFFFF;
    --text: var(--zen-navy);
    --text-light: var(--zen-slate);
  }
  
  /* ---------------------------------------------------------------------------------- 
     Base reset
     ----------------------------------------------------------------------------------  */
  
  *,
  *::before,
  *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  
  html {
    scroll-behavior: smooth;
    scroll-padding-top: 72px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
  }
  
  body {
    font-family: var(--font-body);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.65;
    font-size: 15px;
  }
  
  img,
  svg {
    display: block;
    max-width: 100%;
    height: auto;
  }
  
  a {
    color: var(--zen-teal);
    text-decoration: none;
    transition: color var(--transition);
  }
  
  a:hover {
    color: var(--zen-teal-dark);
  }
  
  ::selection {
    background: rgba(31, 167, 138, 0.18);
  }
  
  :focus-visible {
    outline: 2px solid var(--zen-teal);
    outline-offset: 3px;
    border-radius: var(--radius-sm);
  }
  
  /* Layout helpers */
  
  .zen-container {
    max-width: 1200px;
    margin-inline: auto;
    padding-inline: clamp(1rem, 4vw, 2.5rem);
  }
  
  .zen-container--wide {
    max-width: 1400px;
    margin-inline: auto;
    padding-inline: clamp(1rem, 4vw, 2.5rem);
  }
  
  /* ---------------------------------------------------------------------------------- 
     Site header
     ----------------------------------------------------------------------------------  */
  
  .zen-header {
    background: linear-gradient(
      90deg,
      #163a59 0%,
      var(--zen-navy) 72%
    );
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.18);
    transition: box-shadow 0.25s var(--transition);
  }
  
  .zen-header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-block: 0.5rem;
    min-height: 64px;
    gap: var(--space-6);
  }
  
  /* Logo */
  
  .zen-logo-link {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: 0;
    border: 0;
    border-radius: 0;
    background: transparent;
    box-shadow: none;
    text-decoration: none;
    flex-shrink: 0;
  }

  .zen-logo-img {
    height: 45px;
    width: auto;
    filter: drop-shadow(0 1px 1px rgba(0, 0, 0, 0.28));
  }
  
  /* Nav */
  
  .zen-nav {
    display: flex;
    align-items: center;
    gap: 4px;
  }
  
  .zen-nav-link {
    color: rgba(255, 255, 255, 0.72);
    text-decoration: none;
    font-weight: 500;
    font-size: var(--text-xs);
    letter-spacing: 0.01em;
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
    transition:
      background var(--transition),
      color var(--transition);
    white-space: nowrap;
  }
  
  .zen-nav-link:hover,
  .zen-nav-link.active,
  .zen-nav-link--active {
    background: rgba(31, 167, 138, 0.15);
    color: #1FA78A;
  }
  
  .zen-nav-link--home {
    color: var(--zen-teal);
  }
  
  /* Back-link for sub-pages */
  
  .zen-back-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    color: rgba(255, 255, 255, 0.55);
    font-size: var(--text-xs);
    font-weight: 500;
    padding: var(--space-1) var(--space-3);
    border-radius: var(--radius-md);
    transition:
      color var(--transition),
      background var(--transition);
  }
  
  .zen-back-link:hover {
    color: #fff;
    background: rgba(255, 255, 255, 0.08);
  }
  
  .zen-back-link svg {
    width: 14px;
    height: 14px;
  }
  
  /* Mobile hamburger */
  
  .zen-menu-toggle {
    display: none;
    background: none;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    color: rgba(255, 255, 255, 0.8);
    padding: var(--space-2) var(--space-3);
    cursor: pointer;
    font-size: 18px;
    line-height: 1;
  }

  @media (max-width: 900px) {
    .zen-menu-toggle {
      display: flex;
      align-items: center;
      justify-content: center;
    }
  
    .zen-nav {
      display: none;
      position: absolute;
      top: 100%;
      left: 0;
      right: 0;
      flex-direction: column;
      align-items: stretch;
      gap: 0;
      background: var(--zen-navy);
      padding: var(--space-3);
      box-shadow: 0 8px 20px rgba(0, 0, 0, 0.25);
    }
  
    .zen-nav.open {
      display: flex;
    }
  
    .zen-nav-link {
      white-space: normal;
      width: 100%;
      padding: var(--space-3);
    }
  }
  
/* ----------------------------------------------------------------------------------
   Sponsor acknowledgement
   ---------------------------------------------------------------------------------- */

   .zen-sponsor {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    text-decoration: none;
    flex-shrink: 0;
  }
  
  .zen-sponsor-label {
    color: rgba(255, 255, 255, 0.48);
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 0.07em;
    line-height: 1;
    text-transform: uppercase;
    white-space: nowrap;
  }
  
  .zen-sponsor-logo {
    display: block;
    width: auto;
    object-fit: contain;
    transition: opacity var(--transition);
  }
  
  /* Header: deliberately restrained. */
  .zen-sponsor--header {
    padding-left: var(--space-4);
    border-left: 1px solid rgba(255, 255, 255, 0.16);
  }
  
  .zen-sponsor--header .zen-sponsor-logo {
    height: 26px;
    max-width: 96px;
  }
  
  .zen-sponsor--header:hover .zen-sponsor-logo {
    opacity: 0.82;
  }
  
  /* Footer: more visual space for the acknowledgment. */
  .zen-sponsor--footer {
    margin-top: var(--space-1);
    padding: 0;
    border: none;
    border-radius: 0;
    background: transparent;
  }
  
  .zen-sponsor--footer .zen-sponsor-logo {
    height: 34px;
    max-width: 150px;
  }
  
  .zen-sponsor--footer:hover {
    background: transparent;
  }
  
  .zen-sponsor--footer:hover .zen-sponsor-logo {
    opacity: 0.82;
  }
  
  @media (max-width: 1100px) {
    .zen-sponsor--header {
      display: none;
    }
  }

  /* ---------------------------------------------------------------------------------- 
     Site footer
     ----------------------------------------------------------------------------------  */
  
  .zen-footer {
    background: var(--zen-navy);
    color: rgba(255, 255, 255, 0.45);
    padding-block: var(--space-10);
    margin-top: var(--space-16);
    font-size: var(--text-xs);
  }
  
  .zen-footer-inner {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-4);
    text-align: center;
  }
  
  .zen-footer-logo {
    height: 40px;
    width: auto;
    opacity: 0.8;
    filter: brightness(0) invert(1);
  }
  
  .zen-footer-links {
    display: flex;
    gap: var(--space-5);
    flex-wrap: wrap;
    justify-content: center;
  }
  
  .zen-footer-links a {
    color: rgba(255, 255, 255, 0.45);
    font-size: var(--text-xs);
    transition: color var(--transition);
  }
  
  .zen-footer-links a:hover {
    color: var(--zen-teal);
  }
  
  /* -------------------------
     Reading progress bar (articles)
     ------------------------- */
  
  #zen-reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    width: 0;
    height: 3px;
    background: var(--zen-teal);
    z-index: 2000;
    transition: width 0.1s linear;
  }
  
  /* ---------------------------------------------------------------------------------- 
     Home page: hero + sections
     ----------------------------------------------------------------------------------   */
  
  .zen-hero {
    background: linear-gradient(
        135deg,
        var(--zen-navy) 0%,
        #1a4a6e 55%,
        #1a5a6a 100%
    );
    color: #fff;
    padding-block: clamp(var(--space-3), 5vw, 56px);
    position: relative;
    overflow: hidden;
    text-align: center;
  }
  
  .zen-hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background:
      radial-gradient(circle at 80% 20%, rgba(31, 167, 138, 0.14) 0, transparent 50%),
      radial-gradient(circle at 15% 75%, rgba(31, 167, 138, 0.07) 0, transparent 40%);
    pointer-events: none;
  }
  
  .zen-hero::after {
    content: "";
    position: absolute;
    right: -100px;
    top: -100px;
    width: 500px;
    height: 500px;
    border-radius: 50%;
    border: 50px solid rgba(255, 255, 255, 0.03);
    pointer-events: none;
  }
  
  .zen-hero-content {
    position: relative;
    z-index: 1;
    max-width: 780px;
    margin-inline: auto;
  }
  
  .zen-hero h1 {
    font-size: var(--text-2xl);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-3);
    color: #fff;
  }
  
  .zen-hero-sub {
    font-size: var(--text-base);
    color: rgba(255, 255, 255, 0.65);
    max-width: 58ch;
    margin-inline: auto;
    margin-bottom: var(--space-3);
    line-height: 1.65;
  }
  
  .zen-hero-stats {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--space-8);
    margin-top: var(--space-2);
  }
  
  .zen-hero-stat-value {
    display: block;
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--zen-teal);
  }
  
  .zen-hero-stat-label {
    display: block;
    font-size: var(--text-xs);
    color: rgba(255, 255, 255, 0.45);
    text-transform: uppercase;
    letter-spacing: 0.07em;
  }
  
  /* Sections on home */
  
  .zen-section {
    padding-block: clamp(var(--space-12), 7vw, 90px);
  }
  
  .zen-section--alt {
    background: var(--color-surface);
  }
  
  .zen-section-title {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--zen-navy);
    text-align: center;
    letter-spacing: -0.02em;
    margin-bottom: var(--space-2);
  }
  
  .zen-section-subtitle {
    text-align: center;
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    margin-bottom: var(--space-10);
    max-width: 60ch;
    margin-inline: auto;
    line-height: 1.6;
  }
  
  /* Card grid */
  
  .zen-card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--space-5);
  }
  
  /* Generic cards and article cards */
  
  .zen-card,
  .zen-article-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition:
      transform var(--transition),
      box-shadow var(--transition);
  }
  
  .zen-card:hover,
  .zen-article-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
  }
  
  a.zen-card,
  a.zen-article-card {
    cursor: pointer;
  }

  .zen-card-grid-break {
    grid-column: 1 / -1;
    height: 0;
  }
  
  /* Card body */
  
  .zen-card-body {
    padding: var(--space-6);
    display: flex;
    flex-direction: column;
    flex: 1;
  }
  
  .zen-card-body h3 {
    font-size: var(--text-base);
    font-weight: 700;
    color: var(--zen-navy);
    margin: var(--space-3) 0 var(--space-2);
    line-height: 1.3;
  }
  
  .zen-card-body p {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    line-height: 1.6;
    flex: 1;
    margin-bottom: var(--space-5);
  }
  
  .zen-card-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    color: var(--zen-teal);
    font-weight: 600;
    font-size: var(--text-sm);
    margin-top: auto;
    transition:
      gap var(--transition),
      color var(--transition);
  }
  
  .zen-card-link svg {
    width: 16px;
    height: 16px;
  }
  
  .zen-card-link:hover {
    color: var(--zen-teal-dark);
    gap: var(--space-3);
  }
  
  /* Placeholder cards */
  
  .zen-card--placeholder {
    border: 2px dashed var(--color-border);
    background: transparent;
    box-shadow: none;
  }
  
  .zen-card--placeholder:hover {
    transform: none;
    box-shadow: none;
  }
  
  .zen-card--placeholder h3 {
    color: var(--color-text-faint);
  }
  
  .zen-card--placeholder p {
    color: var(--color-text-faint);
  }
  
  /* Badges */
  
  .zen-badge {
    align-self: flex-start;
    display: inline-flex;
    align-items: center;
    padding: 3px 9px;
    border-radius: 999px;
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    color: #fff;
  }
  
  .zen-badge--teal {
    background: var(--zen-teal);
  }
  
  .zen-badge--navy {
    background: var(--zen-navy);
  }
  
  .zen-badge--blue {
    background: #0984e3;
  }
  
  .zen-badge--purple {
    background: var(--purple);
  }
  
  .zen-badge--warning {
    background: var(--warning);
    color: var(--zen-navy);
  }
  
  .zen-badge--success {
    background: var(--success);
  }
  
  .zen-badge--slate {
    background: var(--zen-slate);
  }
  
  /* Article card specifics */
  
  .zen-article-card-banner {
    background: linear-gradient(
      135deg,
      var(--zen-navy) 0%,
      #1a5a6a 100%
    );
    padding: var(--space-6) var(--space-6) var(--space-5);
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: var(--space-4);
  }
  
  .zen-article-card-icon {
    width: 48px;
    height: 48px;
    background: rgba(31, 167, 138, 0.18);
    border: 1px solid rgba(31, 167, 138, 0.3);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
  }
  
  .zen-article-card-icon svg {
    color: var(--zen-teal);
    width: 24px;
    height: 24px;
  }
  
  .zen-article-card-meta {
    color: rgba(255, 255, 255, 0.45);
    font-size: 10px;
    text-transform: uppercase;
    letter-spacing: 0.08em;
  }
  
  .zen-article-card-body {
    padding: var(--space-5) var(--space-6) var(--space-6);
    flex: 1;
    display: flex;
    flex-direction: column;
  }
  
  .zen-article-card-body h3 {
    font-size: var(--text-base);
    font-weight: 700;
    color: var(--zen-navy);
    margin-bottom: var(--space-2);
  }
  
  .zen-article-card-body p {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    line-height: 1.6;
    flex: 1;
    margin-bottom: var(--space-5);
  }
  
  /* Simple placeholder content blocks */
  
  .zen-placeholder {
    background: var(--color-surface);
    border-left: 4px solid var(--zen-teal);
    border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
    padding: var(--space-5) var(--space-6);
    max-width: 780px;
    margin-inline: auto;
    box-shadow: var(--shadow-sm);
  }
  
  .zen-placeholder p {
    color: var(--color-text-muted);
    font-style: italic;
    font-size: var(--text-sm);
    line-height: 1.7;
  }
  
  /* About / contact blocks */
  
  .zen-about-block,
  .zen-contact-block {
    max-width: 720px;
    margin-inline: auto;
    text-align: center;
  }
  
  .zen-about-block p,
  .zen-contact-block p {
    font-size: var(--text-base);
    color: var(--color-text-muted);
    line-height: 1.8;
    margin-bottom: var(--space-4);
  }
  
  .zen-about-block p:last-child,
  .zen-contact-block p:last-child {
    margin-bottom: 0;
  }
  
  .zen-contact-block a {
    color: var(--zen-teal);
    font-weight: 600;
  }
  
  /* About section with portrait */

  .zen-about-layout {
    display: grid;
    grid-template-columns: minmax(180px, 260px) minmax(0, 1fr);
    align-items: center;
    gap: clamp(var(--space-6), 5vw, var(--space-12));
    max-width: 920px;
    margin: var(--space-8) auto 0;
  }

  .zen-about-portrait-wrap {
    width: 100%;
    max-width: 260px;
    aspect-ratio: 1 / 1;
    justify-self: center;
    overflow: hidden;
    border: 3px solid var(--zen-teal);
    border-radius: var(--radius-xl);
    background: var(--color-surface-2);
    box-shadow: var(--shadow-md);
  }

  .zen-about-portrait {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
  }

  .zen-about-layout .zen-about-block {
    max-width: none;
    margin: 0;
    text-align: left;
  }

  @media (max-width: 640px) {
    .zen-about-layout {
      grid-template-columns: 1fr;
      gap: var(--space-6);
      margin-top: var(--space-6);
    }

    .zen-about-portrait-wrap {
      max-width: 210px;
    }

    .zen-about-layout .zen-about-block {
      text-align: center;
    }
  }

  /* ---------------------------------------------------------------------------------- 
     Tool pages (Beam, Bolt, etc.)
     ----------------------------------------------------------------------------------  */
  
  body.zen-tool-page {
    background: var(--color-bg);
    padding: 0;
    font-size: 14px;
  }
  
/* ------------------------------------------------------------------
   Tool introduction
   ------------------------------------------------------------------ */

   .zen-tool-intro {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: var(--space-6);
    padding: clamp(var(--space-6), 4vw, var(--space-10)) 0 var(--space-6);
    margin-bottom: var(--space-5);
    border-bottom: 1px solid var(--color-divider);
  }
  
  .zen-tool-intro__identity {
    min-width: 0;
  }
  
  .zen-tool-intro__title {
    margin: 0;
    color: var(--zen-navy);
    font-size: var(--text-xl);
    font-weight: 750;
    line-height: 1.15;
    letter-spacing: -0.025em;
  }
  
  .zen-tool-intro__version {
    color: var(--color-text-muted);
    font-size: 0.7em;
    font-weight: 550;
    letter-spacing: 0;
    white-space: nowrap;
  }
  
  .zen-tool-intro__subtitle {
    max-width: 68ch;
    margin: var(--space-2) 0 0;
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    line-height: 1.55;
  }
  
  .zen-tool-intro__actions {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    flex: 0 0 auto;
  }
  
  .zen-tool-setting {
    display: flex;
    align-items: center;
    gap: var(--space-2);
  }
  
  .zen-tool-setting__label,
  body.zen-tool-page .zen-tool-intro .zen-tool-setting label {
    margin: 0;
    color: var(--color-text-muted);
    font-size: var(--text-xs);
    font-weight: 650;
    white-space: nowrap;
  }
  
  .zen-unit-toggle {
    display: inline-flex;
    overflow: hidden;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    box-shadow: var(--shadow-sm);
  }
  
  .zen-unit-toggle button {
    min-height: 36px;
    padding: 0.45rem 0.75rem;
    border: 0;
    border-right: 1px solid var(--color-border);
    background: transparent;
    color: var(--color-text-muted);
    cursor: pointer;
    font: inherit;
    font-size: 0.7rem;
    font-weight: 750;
    letter-spacing: 0.06em;
  }
  
  .zen-unit-toggle button:last-child {
    border-right: 0;
  }
  
  .zen-unit-toggle button:hover {
    background: var(--color-surface-2);
    color: var(--color-text);
  }
  
  .zen-unit-toggle button.active {
    background: var(--zen-teal);
    color: #fff;
  }
  
  body.zen-tool-page .zen-tool-intro .zen-tool-setting select {
    width: auto;
    min-width: 76px;
    padding: 0.5rem 0.65rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-surface);
    color: var(--color-text);
    font: inherit;
    font-size: var(--text-sm);
    font-weight: 650;
  }

  .zen-tool-intro__actions-group {
    display: flex;
    align-items: center;
    gap: var(--space-6);
    flex: 0 0 auto;
  }
  
  @media (max-width: 680px) {
    .zen-tool-intro__actions-group {
      flex-direction: column;
      width: 100%;
      align-items: stretch;
      gap: var(--space-4);
    }
  }

  @media (max-width: 680px) {
    .zen-tool-intro {
      align-items: flex-start;
      flex-direction: column;
      gap: var(--space-4);
      padding-top: var(--space-5);
    }
  
    .zen-tool-intro__actions {
      width: 100%;
    }
  
    .zen-tool-setting {
      width: 100%;
      justify-content: space-between;
    }
  
    body.zen-tool-page .zen-tool-intro .zen-tool-setting select {
      min-width: 100px;
    }
  }
  
  /* Toggle switch */

  .zen-switch {
    position: relative;
    display: inline-block;
    width: 40px;
    height: 20px;
  }

  .zen-switch input {
    opacity: 0;
    width: 0;
    height: 0;
  }

  .zen-slider {
    position: absolute;
    cursor: pointer;
    inset: 0;
    background: #ccc;
    transition: 0.3s;
    border-radius: 20px;
  }

  .zen-slider::before {
    position: absolute;
    content: "";
    height: 14px;
    width: 14px;
    left: 3px;
    bottom: 3px;
    background: #fff;
    transition: 0.3s;
    border-radius: 50%;
  }

  .zen-switch input:checked + .zen-slider {
    background: var(--success);
  }

  .zen-switch input:checked + .zen-slider::before {
    transform: translateX(20px);
  }

  /* Toggle row inside a card */

  .zen-switch-box {
    background: #f8f9fa;
    padding: var(--space-4);
    border-radius: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin: var(--space-4) 0;
    border: 1px solid #eee;
  }

  .zen-switch-label {
    font-size: 13px;
    font-weight: 800;
}

  /* Tool body wrapper */
  
  .zen-tool-body,
  body.zen-tool-page .container {
    max-width: 1400px;
    margin-inline: auto;
    padding: 0 clamp(1rem, 3vw, 2rem) clamp(2rem, 4vw, 3rem);
  }
  
  /* Tool footer */
  
  .zen-tool-footer {
    background: var(--zen-navy);
    color: rgba(255, 255, 255, 0.35);
    text-align: center;
    font-size: 12px;
    padding: var(--space-5) var(--space-4);
    margin-top: var(--space-12);
  }
  
  /* Shared tool-page components */
  
  .card {
    background: var(--card-bg);
    padding: 24px;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    border: 1px solid #e1e8ed;
    margin-bottom: 20px;
  }
  
  .card h2 {
    margin-top: 0;
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 1.2px;
    color: #718093;
    font-weight: 700;
    border-bottom: 1px solid #f1f2f6;
    padding-bottom: 10px;
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  
  /* Form elements */
  
  .form-group {
    margin-bottom: 12px;
  }
  
  body.zen-tool-page label {
    display: flex;
    align-items: center;
    font-size: 12px;
    font-weight: 700;
    margin-bottom: 6px;
    color: #4b6584;
  }
  
  body.zen-tool-page select,
  body.zen-tool-page input {
    width: 100%;
    padding: 10px;
    border: 1px solid #dcdde1;
    border-radius: 6px;
    font-size: 14px;
    box-sizing: border-box;
    transition: border-color 0.2s;
  }
  
  body.zen-tool-page select:focus,
  body.zen-tool-page input:focus {
    outline: none;
    border-color: var(--accent);
  }
  
  /* Buttons */
  
  .btn-pdf {
    background: var(--accent);
    color: #fff;
    border: none;
    padding: 10px 18px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    font-size: 13px;
    transition: background 0.2s;
  }
  
  .btn-pdf:hover {
    background: #0773c5;
  }
  
  .btn-add {
    background: var(--success);
    color: #fff;
    border: none;
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 11px;
    font-weight: bold;
  }
  
  .btn-remove {
    background: var(--danger);
    color: #fff;
    border: none;
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    font-size: 11px;
  }
  
  /* Results panel */
  
  .results-panel {
    background: var(--primary);
    color: #fff;
  }
  
  .res-item {
    margin-bottom: 16px;
    border-left: 4px solid var(--accent);
    padding-left: 12px;
  }
  
  .res-label {
    font-size: 11px;
    text-transform: none;
    color: #a4b0be;
    display: flex;
    align-items: center;
    margin-bottom: 2px;
  }
  
  .res-val {
    font-size: 22px;
    font-weight: 900;
    color: #fff;
  }
  
  .res-unit {
    font-size: 12px;
    margin-left: 6px;
    color: var(--accent);
    font-weight: bold;
  }

  .zen-metric-list {
    display: grid;
    gap: 0;
  }

  .zen-metric-row {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    column-gap: var(--space-4);
    row-gap: 3px;
    align-items: baseline;
    padding: 10px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.10);
  }

  .zen-metric-list .zen-metric-row:last-child {
    border-bottom: 0;
    padding-bottom: 0;
  }

  .zen-metric-row__label {
    display: flex;
    align-items: center;
    gap: 0;
    min-width: 0;
    overflow: visible; /* keep tooltip icons from clipping inside grouped cards */
    color: rgba(255, 255, 255, 0.68);
    font-family: var(--font-sans);
    font-size: 11px;
    font-weight: 650;
    line-height: 1.35;
  }

  .zen-metric-row__value {
    color: #fff;
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 750;
    font-variant-numeric: tabular-nums;
    line-height: 1.2;
    text-align: right;
    white-space: nowrap;
  }

  .zen-metric-row__unit {
    margin-left: 4px;
    color: var(--accent);
    font-size: 0.72rem;
    font-weight: 700;
  }

  .zen-metric-row__note {
    grid-column: 1 / -1;
    color: rgba(255, 255, 255, 0.42);
    font-family: var(--font-sans);
    font-size: 10px;
    font-variant-numeric: tabular-nums;
    line-height: 1.35;
    text-align: right;
  }

  /* Grouping: side-by-side sub-cards for multi-body / multi-section results (e.g. Hertz Body 1/2) */

  .zen-metric-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-5);
  }

  .zen-metric-group {
    overflow: visible; /* keep tooltip icons from clipping */
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: var(--radius-lg);
    padding: var(--space-5);
  }

  .zen-metric-group__title {
    margin: 0 0 var(--space-3);
    padding-bottom: var(--space-3);
    border-bottom: 1px solid rgba(255, 255, 255, 0.12);
    color: #fff;
    font-size: var(--text-sm);
    font-weight: 700;
    line-height: 1.3;
  }

  /* Callout: highlighted mono read-out box under the list (e.g. reaction forces) */

  .zen-metric-callout {
    margin-top: var(--space-4);
    padding-top: var(--space-4);
    border-top: 1px solid rgba(255, 255, 255, 0.14);
  }

  .zen-metric-callout__label {
    margin-bottom: var(--space-2);
    color: rgba(255, 255, 255, 0.68);
    font-family: var(--font-sans);
    font-size: 11px;
    font-weight: 650;
  }

  .zen-metric-callout__value {
    padding: var(--space-3);
    border: 1px solid rgba(255, 255, 255, 0.10);
    border-radius: var(--radius-md);
    background: rgba(0, 0, 0, 0.16);
    color: #5ce8c8;
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 11px;
    font-variant-numeric: tabular-nums;
    line-height: 1.65;
  }

  @media (max-width: 900px) {
    .zen-metric-grid {
      grid-template-columns: 1fr;
    }
  }

  .main-grid > *,
  .wide-grid > *,
  .left-col {
    min-width: 0;
  }

  .table-wrap {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .zen-hertz-summary-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
  }
  
  @media (max-width: 640px) {
    .zen-hertz-summary-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }

  @media (max-width: 640px) {
    .zen-metric-group {
      padding: var(--space-4);
    }

    .zen-metric-row {
      column-gap: var(--space-3);
    }

    .zen-metric-row__value {
      font-size: 0.95rem;
    }
  }

  @media print {
    .zen-metric-row { border-bottom-color: #bdc3c7 !important; }
    .zen-metric-row__label,
    .zen-metric-row__note,
    .zen-metric-callout__label { color: #4b6584 !important; }
    .zen-metric-row__value { color: #000 !important; }
    .zen-metric-row__unit { color: #2c3e50 !important; }
    .zen-metric-callout { border-top-color: #bdc3c7 !important; }
    .zen-metric-callout__value { background: #fff !important; border-color: #bdc3c7 !important; color: #000 !important; }
    .zen-metric-group { background: #fff !important; border-color: #bdc3c7 !important; }
    .zen-metric-group__title { color: #2c3e50 !important; border-bottom-color: #bdc3c7 !important; }
  }

  /* Inline tool warning banner */

  .zen-tool-warning {
    display: none;
    background: var(--danger);
    color: #fff;
    padding: var(--space-3) var(--space-4);
    border-radius: 6px;
    margin-bottom: var(--space-5);
    font-weight: bold;
    font-size: 13px;
    text-align: center;
  }

  .zen-tool-warning.is-visible {
    display: block;
  }

  /* Small helper text below inputs or result items */

  .zen-hint {
    font-size: 11px;
    color: #718093;
    margin-top: var(--space-1);
    font-style: italic;
    line-height: 1.5;
  }

  /* Two-column tool grid (e.g. roughing / finishing tables) */

  .zen-table-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-5);
    margin-top: var(--space-8);
  }
  
  .zen-table-grid > * {
    min-width: 0;
  }

  @media (max-width: 768px) {
    .zen-table-grid {
      grid-template-columns: 1fr;
    }
  }

  #tableRough,
  #tableFinish {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  /* Misc shared components */
  
  .status-badge {
    text-align: center;
    padding: 8px;
    border-radius: 5px;
    font-weight: bold;
    font-size: 11px;
    margin-bottom: 20px;
    background: #353b48;
  }
  
  .dynamic-row {
    background: #f8f9fa;
    padding: 14px;
    border-radius: 6px;
    border: 1px solid #e1e8ed;
    margin-bottom: 15px;
  }
  
  /* Compact reference data table */

  .zen-ref-table {
    width: 100%;
    border-collapse: collapse;
    background: #fff;
    font-size: 11px;
    border-radius: 8px;
    overflow: hidden;
  }

  .zen-ref-table th,
  .zen-ref-table td {
    padding: 10px;
    border: 1px solid #f1f2f6;
    text-align: left;
  }

  .zen-ref-table th {
    background: #f8f9fa;
    color: #718093;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-size: 10px;
  }

  .zen-ref-table tr:nth-child(even) {
    background: #fafbfc;
  }

  /* Tooltip */
  .tooltip {
    position: relative;
    z-index: 10;
    display: inline-flex;
    align-items: center;
    margin-inline-start: 3px;
    vertical-align: middle;
    flex-shrink: 0;
    cursor: pointer;
    outline: none;
  }

  .tooltip-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 12px;
    height: 12px;
    line-height: 12px;
    flex-shrink: 0;
    border-radius: 50%;
    background: var(--accent, #1FA78A);
    color: #fff;
    font-size: 9px;
    font-weight: 700;
    text-align: center;
  }

  .tooltip-text {
    visibility: hidden;
    width: var(--zen-tooltip-max-width, 260px);
    background: var(--zen-tooltip-bg, #353b48);
    color: var(--zen-tooltip-text, #fff);
    text-align: left; padding: 12px; border-radius: 6px;
    position: fixed; z-index: 3000;
    top: -9999px; left: -9999px;
    font-size: var(--zen-tooltip-font, 12px); font-weight: 400; line-height: 1.5;
    box-shadow: 0 4px 8px rgba(0,0,0,.4);
    opacity: 0; transition: opacity .3s; pointer-events: none;
  }

  .tooltip:hover,
  .tooltip:focus {
    z-index: 1001;
  }
  
  .tooltip:hover .tooltip-text,
  .tooltip:focus .tooltip-text {
    visibility: visible;
    opacity: 1;
  }

  /* Wider tooltip variant for long formula explanations */
  .tooltip--wide .tooltip-text {
    width: min(420px, calc(100vw - 2rem));
    max-width: calc(100vw - 2rem);
  }

  /* Prevent text transformation issues inherited from brand styles */
  .tooltip-text, .tooltip-text *, .tooltip-icon,
  th .tooltip, th .tooltip-icon {
    text-transform: none !important;
    letter-spacing: normal !important;
  }
  .tooltip-text strong { font-weight: 700 !important; }

  /* Wider tooltip variant for formula-heavy engineering explanations */
  .tooltip--wide .tooltip-text {
    width: min(420px, calc(100vw - 2rem));
    max-width: calc(100vw - 2rem);
  }
  
  
  /* Disclaimer / explainer footer block inside tool pages */
  
  .zen-disclaimer {
    margin-top: 30px;
    padding: 20px;
    background: #2f3640;
    color: #dcdde1;
    border-radius: 10px;
    font-size: 12px;
    line-height: 1.6;
  }
  
  .zen-disclaimer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
  }
  
  .zen-disclaimer-divider {
    border: 0;
    border-top: 1px dashed #485460;
    margin: 20px 0;
  }
  
  .zen-disclaimer strong {
    color: #fff;
    font-size: 11px;
    letter-spacing: 1px;
  }
  
  .zen-disclaimer-detail {
    font-size: 11px;
    color: #b2bec3;
    line-height: 1.5;
  }
  
  .zen-disclaimer-detail ul {
    margin-top: 5px;
    padding-left: 20px;
    list-style-type: disc;
  }
  
  .zen-disclaimer-detail li {
    margin-top: 8px;
  }
  
  /* ----------------------------------------------------------------------------------
     Article pages (Turning, etc.)
     ---------------------------------------------------------------------------------- */
  
  /* Article hero */
  
  .article-hero {
    background: linear-gradient(
      135deg,
      var(--zen-navy) 0%,
      #1a3a5e 50%,
      #163a4a 100%
    );
    color: #fff;
    padding-block: clamp(3rem, 8vw, 5.5rem);
    position: relative;
    overflow: hidden;
  }
  
  .article-hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background:
      radial-gradient(circle at 75% 25%, rgba(31, 167, 138, 0.14) 0, transparent 50%),
      radial-gradient(circle at 20% 75%, rgba(31, 167, 138, 0.07) 0, transparent 40%);
    pointer-events: none;
  }
  
  .article-hero::after {
    content: "";
    position: absolute;
    right: -100px;
    top: -100px;
    width: 500px;
    height: 500px;
    border-radius: 50%;
    border: 50px solid rgba(255, 255, 255, 0.03);
    pointer-events: none;
  }
  
  .article-hero-inner {
    position: relative;
    z-index: 1;
  }
  
  /* Hero meta */
  
  .hero-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    align-items: center;
    margin-bottom: 1.25rem;
  }
  
  .hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: rgba(31, 167, 138, 0.2);
    border: 1px solid rgba(31, 167, 138, 0.35);
    color: #5CE8C8;
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 4px 12px;
    border-radius: 999px;
  }
  
  .hero-badge svg {
    width: 12px;
    height: 12px;
  }
  
  .hero-doc-id {
    font-size: 11px;
    color: rgba(255, 255, 255, 0.4);
  }
  
  .article-hero h1 {
    font-size: var(--text-hero);
    font-weight: 800;
    color: #fff;
    letter-spacing: -0.03em;
    line-height: 1.05;
    margin-bottom: 1rem;
    max-width: 14ch;
  }
  
  .hero-subtitle {
    font-size: var(--text-base);
    color: rgba(255, 255, 255, 0.62);
    max-width: 52ch;
    line-height: 1.65;
    margin-bottom: 2rem;
  }
  
  /* Article layout */
  
  .article-layout {
    display: grid;
    grid-template-columns: 260px 1fr;
    gap: 3rem;
    max-width: 1280px;
    margin-inline: auto;
    padding: 3rem clamp(1rem, 3vw, 2.5rem) 5rem;
    align-items: flex-start;
  }
  
  /* TOC sidebar */
  
  .toc-sidebar {
    position: sticky;
    top: calc(64px + 1rem);
    max-height: calc(100vh - 80px);
    overflow-y: auto;
    scrollbar-width: thin;
    scrollbar-color: var(--color-border) transparent;
  }
  
  .toc-sidebar::-webkit-scrollbar {
    width: 3px;
  }
  
  .toc-sidebar::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 2px;
  }
  
  .toc-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: 1.25rem;
    box-shadow: var(--shadow-sm);
  }
  
  .toc-title {
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-faint);
    margin-bottom: 0.75rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--color-divider);
  }
  
  .toc-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 2px;
  }
  
  .toc-list li a {
    display: block;
    font-size: 12px;
    color: var(--color-text-muted);
    padding: 5px 10px;
    border-radius: var(--radius-md);
    transition:
      background var(--transition),
      color var(--transition);
    line-height: 1.4;
  }
  
  .toc-list li a:hover,
  .toc-list li a.active {
    background: var(--zen-teal);
    color: #fff;
  }
  
  .toc-list--sub {
    padding-left: 0.75rem;
    margin-top: 2px;
  }
  
  .toc-list--sub li a {
    font-size: 11px;
  }
  
  /* Article content area */
  
  .article-content {
    min-width: 0;
  }
  
  .doc-section {
    margin-bottom: 3rem;
    padding-bottom: 2.5rem;
    border-bottom: 1px solid var(--color-border);
  }
  
  .doc-section:last-child {
    border-bottom: none;
  }
  
  .section-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--color-divider);
  }
  
  .section-number {
    font-size: 11px;
    font-weight: 700;
    color: var(--zen-teal);
    background: rgba(31, 167, 138, 0.12);
    border: 1px solid rgba(31, 167, 138, 0.25);
    padding: 3px 10px;
    border-radius: 999px;
    letter-spacing: 0.05em;
    white-space: nowrap;
  }
  
  .section-title {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--zen-navy);
    letter-spacing: -0.02em;
  }
  
  .subsection {
    margin-top: 2.5rem;
    margin-bottom: 1.5rem;
  }
  
  .subsection-title {
    font-size: var(--text-lg);
    font-weight: 600;
    color: var(--zen-navy);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  .subsection-title::before {
    content: "";
    display: block;
    width: 4px;
    height: 1.1em;
    background: var(--zen-teal);
    border-radius: 2px;
    flex-shrink: 0;
  }
  
  .subsubsection-title {
    font-size: var(--text-base);
    font-weight: 600;
    color: var(--zen-navy);
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
  }
  
  .doc-p {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    line-height: 1.75;
    margin-bottom: 0.85rem;
  }
  
  .doc-list {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    line-height: 1.7;
    padding-left: 1.4rem;
    margin-bottom: 0.85rem;
  }
  
  .doc-list li {
    margin-bottom: 0.35rem;
  }
  
  /* Figures */
  
  .figure-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 1.25rem 0;
    justify-content: flex-start;
  }
  
  .doc-figure {
    flex: 1 1 260px;
    max-width: 480px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin: 0;
  }
  
  .doc-figure img {
    width: 100%;
    height: auto;
    display: block;
    object-fit: contain;
    max-height: 320px;
  }
  
  .doc-figure-solo {
    max-width: 580px;
  }
  
  .doc-figure-wide {
    max-width: 100%;
    flex-basis: 100%;
  }
  
  .doc-figcaption {
    font-size: 11px;
    color: var(--color-text-muted);
    text-align: center;
    padding: 0.5rem 0.75rem;
    border-top: 1px solid var(--color-border);
    font-style: italic;
  }
  
  /* Tables */
  
  .doc-table-wrapper {
    overflow-x: auto;
    margin: 1rem 0 1.5rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
  }
  
  .doc-table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--text-sm);
  }
  
  .doc-table th {
    background: var(--zen-navy);
    color: #fff;
    padding: 10px 14px;
    text-align: left;
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
  }
  
  .doc-table td {
    padding: 8px 14px;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-text-muted);
  }
  
  .doc-table tr:last-child td {
    border-bottom: none;
  }
  
  .doc-table tr:nth-child(even) td {
    background: var(--color-surface-2);
  }
  
  .table-caption {
    font-size: 11px;
    font-weight: 700;
    color: var(--zen-slate);
    margin-bottom: 0.4rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
  }
  
  /* Callouts */
  
  .doc-callout {
    background: rgba(31, 167, 138, 0.08);
    border-left: 3px solid var(--zen-teal);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: 1rem 1.25rem;
    margin: 1.25rem 0;
    font-size: var(--text-sm);
    color: var(--color-text);
    line-height: 1.65;
  }
  
  .doc-callout p {
    margin: 0;
    max-width: none;
  }
  
  .doc-callout strong {
    color: var(--zen-navy);
  }
  
  .doc-callout--warn {
    background: rgba(253, 203, 110, 0.1);
    border-left-color: #f9ca24;
  }
  
  /* Doc info grid */
  
  .doc-info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 1.25rem;
  }
  
  .doc-info-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 0.75rem 1rem;
  }
  
  .doc-info-label {
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--zen-teal);
    margin: 0 0 0.25rem;
  }
  
  .doc-info-value {
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--zen-navy);
    margin: 0;
  }
  
  /* Step-numbered list */
  
  .step-list {
    list-style: none;
    padding: 0;
    counter-reset: step-counter;
    margin: 0.75rem 0 1rem;
  }
  
  .step-list li {
    counter-increment: step-counter;
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    font-size: var(--text-sm);
    color: var(--color-text-muted);
    line-height: 1.65;
    margin-bottom: 0.5rem;
  }
  
  .step-list li::before {
    content: counter(step-counter);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 22px;
    height: 22px;
    background: var(--zen-teal);
    color: #fff;
    font-size: 10px;
    font-weight: 700;
    border-radius: 50%;
    flex-shrink: 0;
    margin-top: 2px;
  }
  
  /* Notes / references */
  
  .doc-note {
    display: inline-flex;
    align-items: flex-start;
    gap: 0.5rem;
    background: var(--color-surface-2);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 0.625rem 1rem;
    font-size: 13px;
    color: var(--color-text-muted);
    margin: 1rem 0;
    line-height: 1.55;
  }
  
  .doc-note svg {
    flex-shrink: 0;
    margin-top: 1px;
  }
  
  .iso-ref {
    display: inline-flex;
    align-items: center;
    background: var(--color-surface-2);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 1px 7px;
    font-size: 11px;
    font-weight: 700;
    color: var(--color-text-muted);
    letter-spacing: 0.04em;
    white-space: nowrap;
  }
  
  /* DIN ref badge used in tables */
  
  .din-ref {
    display: inline-block;
    background: var(--zen-navy);
    color: #fff;
    font-size: 10px;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 4px;
    letter-spacing: 0.04em;
  }
  
  /* Disable scroll reveal for stable TOC behaviour */
  
  .reveal,
  .reveal.visible {
    opacity: 1;
    transform: none;
    transition: none;
  }
  
  /* -------------------------
     Responsive
     ------------------------- */
  
  @media (max-width: 900px) {
 
    .zen-header-inner {
      flex-wrap: wrap;
      padding-block: var(--space-3);
    }
  
    .zen-hero h1 {
      font-size: var(--text-xl);
    }
  
    .article-layout {
      grid-template-columns: 1fr;
    }
  
    .toc-sidebar {
      position: static;
      max-height: none;
    }
  
    .figure-row {
      display: grid;
      grid-template-columns: 1fr;
    }
  }
  
  @media (max-width: 600px) {
    .zen-card-grid {
      grid-template-columns: 1fr;
    }
  
    .zen-hero-stats {
      flex-direction: column;
      gap: var(--space-4);
    }
  }
  
  /* -------------------------
     Print tweaks for tools
     ------------------------- */
  
     @page {
      size: A4;
      margin: 12mm 10mm;
    }
    
    @media print {
      html, body {
        background: #ffffff !important;
        color: #000000 !important;
        font-size: 11px;
      }
    
      header.zen-header,
      footer.zen-footer,
      .zen-menu-toggle,
      .zen-tool-intro__actions,
      .btn-pdf,
      .btn-add,
      .btn-remove,
      .btn-secondary,
      .zen-sponsor,
      button:not(.keep-print) {
        display: none !important;
      }
    
      a { color: inherit !important; text-decoration: none !important; }
    
      .card,
      .results-panel,
      .status-badge,
      .zen-metric-group,
      .summary-box,
      .formula-box {
        break-inside: avoid;
        page-break-inside: avoid;
        box-shadow: none !important;
        border: 1px solid #bdc3c7 !important;
      }
    
      .main-grid,
      .wide-grid {
        grid-template-columns: 1fr !important;
        gap: 10px !important;
      }
    
      /* Long/dynamic tables (e.g. bolt force table): let the table span pages,
         but never split a single row, and repeat the header on every page */
      table {
        break-inside: auto;
      }
      thead {
        display: table-header-group;
      }
      tr {
        break-inside: avoid;
        page-break-inside: avoid;
      }
      .table-wrap {
        max-height: none !important;
        overflow: visible !important;
      }

      .status-badge {
        background: #ecf0f1 !important;
        color: #2c3e50 !important;
        border: 1px solid #bdc3c7 !important;
      }
      footer {
        background: #ffffff !important;
        color: #2c3e50 !important;
        border: 1px solid #bdc3c7 !important;
      }
      footer strong { color: #000000 !important; }
    }

  /* Keep structure; print-specific overrides remain in each tool HTML */

  /* ------------------------------------------------------------------
   MathJax equations
   Shared display-math spacing and responsive overflow handling.
   ------------------------------------------------------------------ */

mjx-container[display="true"] {
  display: block;
  max-width: 100%;
  margin: 0.9rem 0 !important;
  overflow-x: auto;
  overflow-y: hidden;
  text-align: center;
}

mjx-container {
  color: currentColor;
}