/* ============================================ TOKENS ============================================ */
:root {
  --paper:       #F2EBD9;
  --paper-soft:  #F8F2E2;
  --paper-warm:  #EFE6D0;
  --alkali:      #E5ECF6;
  --alkali-soft: #EFF3FA;
  --navy:        #0F1E36;
  --navy-deep:   #091428;
  --navy-soft:   #23304A;
  --cobalt:      #1E5BA8;
  --cobalt-bright: #2E7DD1;
  --cobalt-pale: #A8C0E0;
  --bronze:      #B87333;
  --phosphorus:  #D4A038;
  --litmus:      #C04A3D;
  --ash:         #5A6573;
  --ash-soft:    #8C95A2;
  --line:        rgba(30,91,168,0.16);
  --line-warm:   rgba(184,115,51,0.22);

  --font-display: 'Fraunces', serif;
  --font-sans:    'Inter Tight', system-ui, sans-serif;
  --font-mono:    'JetBrains Mono', monospace;

  --ease-out-soft: cubic-bezier(.22,.61,.36,1);
  --ease-out-snap: cubic-bezier(.16,1,.3,1);
}

/* ============================================ BASE ============================================ */
html { scroll-behavior: smooth; scroll-padding-top: 5rem; }
@media (max-width: 767px) { html { scroll-padding-top: 8rem; } }
body {
  font-feature-settings: 'ss01','ss02','cv11';
  -webkit-font-smoothing: antialiased;
  background-color: var(--paper);
  color: var(--navy);
  text-rendering: optimizeLegibility;
}

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--paper-soft); }
::-webkit-scrollbar-thumb { background: var(--cobalt-pale); border-radius: 5px; }
::-webkit-scrollbar-thumb:hover { background: var(--cobalt); }
::selection { background: var(--cobalt); color: var(--paper); }

/* Anchor focus states */
a:focus-visible,
button:focus-visible,
summary:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--cobalt);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ============================================ HEADER ============================================ */
#site-header {
  backdrop-filter: blur(0);
  background: transparent;
  transition: backdrop-filter 0.35s ease, background 0.35s ease, border-color 0.35s ease, padding 0.3s ease;
  border-bottom: 1px solid transparent;
}
#site-header.scrolled {
  backdrop-filter: blur(18px) saturate(1.3);
  -webkit-backdrop-filter: blur(18px) saturate(1.3);
  background: rgba(248,242,226,0.78);
  border-bottom-color: var(--line);
}

/* Mobile section nav — iOS-style segmented control (mobile only) */
.mobile-tabs {
  /* Full-bleed band under the logo row; safe-area aware for notch + home indicator */
  padding: 0.4rem calc(0.9rem + env(safe-area-inset-right))
           calc(0.5rem + env(safe-area-inset-bottom) * 0)
           calc(0.9rem + env(safe-area-inset-left));
  border-top: 1px solid var(--line);
  background: rgba(248,242,226,0.92);
  -webkit-backdrop-filter: blur(14px) saturate(1.3);
  backdrop-filter: blur(14px) saturate(1.3);
}

/* The segmented track: one rounded container, 5 equal segments — no horizontal scroll */
.seg-control {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  align-items: stretch;
  width: 100%;
  padding: 3px;
  gap: 2px;
  border: 1px solid var(--line);
  border-radius: 11px;
  background: rgba(15,30,54,0.05);
  /* hairline inset on the track itself for a crisp glass edge on Retina */
  box-shadow: inset 0 1px 1px rgba(15,30,54,0.04);
}

/* Each segment */
.seg {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;            /* >= comfortable iOS tap target inside a 44px+ band */
  padding: 0 0.25rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  letter-spacing: 0.02em;
  line-height: 1;
  text-align: center;
  color: var(--ash);
  background: transparent;
  border-radius: 8px;
  white-space: nowrap;
  -webkit-tap-highlight-color: transparent;
  transition: background-color .28s var(--ease-out-snap),
              color .28s var(--ease-out-snap),
              box-shadow .28s var(--ease-out-snap);
}
.seg:hover { color: var(--navy); }

/* Active segment — filled cobalt, lifted like a real iOS segmented control */
.seg[aria-current="true"] {
  color: var(--paper);
  background: var(--cobalt);
  box-shadow: 0 1px 2px rgba(15,30,54,0.18), 0 0 0 0.5px rgba(15,30,54,0.06);
}
.seg[aria-current="true"]:hover { color: var(--paper); }

/* Keep the focus ring tight to the rounded segment, not the whole track */
.seg:focus-visible {
  outline: 2px solid var(--cobalt);
  outline-offset: 2px;
  border-radius: 8px;
}

.nav-link {
  position: relative;
  transition: color .25s var(--ease-out-soft);
}
.nav-link:hover { color: var(--cobalt); }
.nav-link::after {
  content: '';
  position: absolute;
  left: 0; right: 0; bottom: -6px;
  height: 1px;
  background: var(--cobalt);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .35s var(--ease-out-soft);
}
.nav-link:hover::after { transform: scaleX(1); }

/* Nav enquire link — small reaction arrow */
.rx-link {
  display: inline-flex;
  align-items: center;
  gap: .55rem;
  padding: .55rem 1.05rem;
  font-size: .8rem;
  font-weight: 500;
  border-radius: 999px;
  color: var(--cobalt);
  border: 1px solid var(--cobalt);
  background: rgba(30,91,168,0.04);
  transition: all .28s var(--ease-out-soft);
  position: relative;
}
.rx-link:hover {
  background: var(--cobalt);
  color: var(--paper-soft);
}
.rx-link svg { transition: transform .35s var(--ease-out-soft); }
.rx-link:hover svg { transform: translateX(3px); }

/* ============================================ HERO ============================================ */
.hero-section {
  background:
    radial-gradient(60% 80% at 80% 20%, rgba(30,91,168,0.05), transparent 70%),
    radial-gradient(50% 70% at 10% 90%, rgba(184,115,51,0.04), transparent 70%),
    var(--paper);
}

.hero-eyebrow, .hero-title, .hero-sub, .hero-cta, .hero-trust {
  opacity: 0;
  transform: translateY(20px);
  animation: heroIn 1s var(--ease-out-soft) forwards;
}
.hero-eyebrow { animation-delay: .1s; }
.hero-title   { animation-delay: .2s; }
.hero-sub     { animation-delay: .4s; }
.hero-cta     { animation-delay: .55s; }
.hero-trust   { animation-delay: .7s; }
@keyframes heroIn { to { opacity: 1; transform: translateY(0); } }

.benzene-svg { opacity: 0; animation: benzeneIn 1.4s .4s var(--ease-out-soft) forwards; }
@keyframes benzeneIn { to { opacity: 1; } }
.benzene-rotate { animation: spinSlow 80s linear infinite; transform-box: fill-box; }
@keyframes spinSlow { to { transform: rotate(360deg); } }
.canvas-loaded .benzene-svg { display: none; }

/* ============================================ WATERMARK · EQUATION TYPOGRAPHY ============================================ */
.watermark {
  position: absolute;
  inset: 0;
  pointer-events: none;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  z-index: 0;
}
.wm-formula {
  font-family: var(--font-display);
  font-weight: 300;
  font-style: italic;
  font-size: clamp(3rem, 11vw, 9rem);
  white-space: nowrap;
  color: var(--cobalt);
  opacity: 0.045;
  letter-spacing: -0.02em;
  user-select: none;
}
.wm-formula sub, .wm-formula sup { font-size: .55em; }
.watermark--hero .wm-formula    { transform: translate(-3%, 8%) rotate(-2deg); opacity: 0.04; }
.watermark--about .wm-formula   { transform: translate(20%, -12%); opacity: 0.05; }
.watermark--teach .wm-formula   { transform: translate(-10%, 12%); opacity: 0.055; }
.watermark--method .wm-formula  { transform: translate(0%, 18%); opacity: 0.05; }
.watermark--results .wm-formula { transform: translate(15%, 14%); opacity: 0.06; }
.watermark--pricing .wm-formula { transform: translate(0%, 16%); opacity: 0.07; }
.watermark--book .wm-formula    { transform: translate(0%, 20%); opacity: 0.05; }
.op-over { font-family: var(--font-mono); font-size: .35em; vertical-align: super; padding: 0 .25em; }

/* ============================================ GLASSWARE LINE-ART ============================================ */
.glassware {
  position: absolute;
  color: var(--cobalt);
  opacity: 0.085;
  pointer-events: none;
  z-index: 0;
  transition: opacity .8s ease;
}
.glassware--hero    { right: -40px; top: 18%; }
.glassware--about   { right: 4%; bottom: 8%; }
.glassware--teach   { right: 6%; top: 12%; transform: rotate(8deg); }
.glassware--method  { left: 2%; bottom: 6%; }
@media (max-width: 768px) {
  .glassware { display: none; }
}

/* ============================================ EQUATION DIVIDER ============================================ */
.equation-divider {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem 1.25rem;
  padding: 2.5rem 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--ash);
  background: var(--paper);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.eq-term { color: var(--navy); font-weight: 500; }
.eq-term--product { color: var(--cobalt); }
.eq-term sub { font-size: .7em; vertical-align: sub; letter-spacing: 0; }
.eq-op { color: var(--cobalt); font-size: 1rem; }
.eq-arrow {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  color: var(--cobalt);
}
.eq-arrow__cond { font-size: .6rem; letter-spacing: 1px; color: var(--ash); }

/* ============================================ TRUST STRIP ============================================ */
.trust-strip {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  position: relative;
}
.trust-cell {
  position: relative;
  padding: 0 0 0 1rem;
  border-left: 1px solid var(--line);
}
.trust-cell:first-child { border-left: 0; padding-left: 0; }
@media (max-width: 1023px) {
  .trust-cell { border-left: 0; padding-left: 0; }
}

/* ============================================ REVEAL ============================================ */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .9s var(--ease-out-soft), transform .9s var(--ease-out-soft); }
.reveal.is-visible { opacity: 1; transform: translateY(0); }

/* ============================================ REACTION ARROW BUTTONS ============================================ */
.rx-btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: .85rem;
  padding: 1.05rem 1.6rem;
  border-radius: 999px;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.005em;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color .3s var(--ease-out-soft),
              color .3s var(--ease-out-soft),
              border-color .3s var(--ease-out-soft),
              transform .3s var(--ease-out-soft),
              box-shadow .3s var(--ease-out-soft);
  white-space: nowrap;
}
.rx-btn--primary {
  background: var(--cobalt);
  color: var(--paper-soft);
  border-color: var(--cobalt);
  box-shadow: 0 1px 0 rgba(15,30,54,0.08), 0 0 0 0 rgba(30,91,168,0.0);
}
.rx-btn--primary:hover {
  background: var(--cobalt-bright);
  border-color: var(--cobalt-bright);
  box-shadow: 0 6px 24px -10px rgba(30,91,168,0.55);
}
.rx-btn--ghost {
  background: transparent;
  color: var(--navy);
  border-color: var(--line);
  padding: 1.05rem 1.4rem;
}
.rx-btn--ghost:hover {
  border-color: var(--cobalt);
  color: var(--cobalt);
  background: rgba(30,91,168,0.04);
}
.rx-btn--lg {
  padding: 1.25rem 2rem;
  font-size: 1rem;
}

/* Reagent label above primary CTA — chemistry-native affordance */
.rx-btn--primary::before {
  content: attr(data-reagent);
  position: absolute;
  top: -1.5em;
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  font-family: var(--font-mono);
  font-size: 9px;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--cobalt);
  opacity: 0;
  transition: opacity .3s var(--ease-out-soft), transform .3s var(--ease-out-soft);
  white-space: nowrap;
  pointer-events: none;
}
.rx-btn--primary:hover::before {
  opacity: 0.72;
  transform: translateX(-50%) translateY(0);
}

.rx-btn__arrow { display: inline-flex; align-items: center; transition: transform .35s var(--ease-out-soft); }
.rx-btn:hover .rx-btn__arrow { transform: translateX(4px); }
.rx-btn__arrow--down {
  display: inline-block;
  transition: transform .35s var(--ease-out-soft);
}
.rx-btn--ghost:hover .rx-btn__arrow--down { transform: translateY(3px); }

/* ============================================ SPEC CARDS ============================================ */
.spec-card {
  position: relative;
  background: var(--paper-soft);
  padding: 2rem 2.25rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  overflow: hidden;
  transition: background-color .45s var(--ease-out-soft),
              border-color .45s var(--ease-out-soft),
              transform .45s var(--ease-out-soft);
}
@media (min-width: 640px) {
  .spec-card { padding: 2.5rem; }
}
.spec-card::before {
  /* Cu²⁺ + 4Cl⁻ → CuCl₄²⁻ — colour change wash on hover */
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(30,91,168,0) 0%, rgba(30,91,168,0.08) 100%);
  opacity: 0;
  transition: opacity .5s var(--ease-out-soft);
  pointer-events: none;
}
.spec-card:hover {
  background: var(--alkali-soft);
  border-color: rgba(30,91,168,0.32);
  transform: translateY(-2px);
}
.spec-card:hover::before { opacity: 1; }

.spec-card__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}
.spec-card__code {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--cobalt);
  letter-spacing: 0.22em;
  text-transform: uppercase;
}
.spec-card__title {
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 300;
  margin-top: .55rem;
  color: var(--navy);
  letter-spacing: -0.01em;
}
@media (min-width: 640px) {
  .spec-card__title { font-size: 1.75rem; }
}
.spec-card__lede {
  margin-top: 1rem;
  font-size: 0.92rem;
  color: rgba(15,30,54,0.65);
  line-height: 1.55;
}
.rxn-dot {
  display: inline-block;
  width: 10px; height: 10px;
  border-radius: 999px;
  background: var(--paper-warm);
  border: 1px solid var(--cobalt);
  transition: background-color .5s var(--ease-out-soft);
}
.spec-card:hover .rxn-dot--blue { background: var(--cobalt); }

/* "I examine this" badge */
.examined-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 9.5px;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--bronze);
  padding: 4px 9px;
  border: 1px solid rgba(184,115,51,0.4);
  border-radius: 999px;
  background: rgba(184,115,51,0.06);
  white-space: nowrap;
}
.examined-badge__dot {
  width: 6px; height: 6px;
  border-radius: 999px;
  background: var(--bronze);
  box-shadow: 0 0 0 0 rgba(184,115,51,0.5);
  animation: examinedPulse 2.4s ease-out infinite;
}
@keyframes examinedPulse {
  0%   { box-shadow: 0 0 0 0 rgba(184,115,51,0.45); }
  70%  { box-shadow: 0 0 0 8px rgba(184,115,51,0); }
  100% { box-shadow: 0 0 0 0 rgba(184,115,51,0); }
}
.spec-card--examined { border-color: rgba(184,115,51,0.28); }
.spec-card--examined::before {
  background: linear-gradient(135deg, rgba(184,115,51,0) 0%, rgba(184,115,51,0.08) 100%);
}
.spec-card--examined:hover { background: #F5EBD8; border-color: rgba(184,115,51,0.5); }

.spec-details { margin-top: 1.4rem; }
.spec-details summary { list-style: none; cursor: pointer; }
.spec-details summary::-webkit-details-marker { display: none; }
.spec-details__label {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--cobalt);
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  transition: color .25s ease;
}
.spec-details__label::after {
  content: '+';
  font-family: var(--font-display);
  font-size: 14px;
  transition: transform .3s var(--ease-out-soft);
}
.spec-details[open] .spec-details__label::after { transform: rotate(45deg); }
.spec-details summary:hover .spec-details__label { color: var(--cobalt-bright); }
.spec-list {
  margin-top: 1rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px 24px;
  font-size: 0.78rem;
  color: rgba(15,30,54,0.62);
  font-feature-settings: 'tnum';
}
.spec-list--two { grid-template-columns: 1fr; }
@media (min-width: 640px) {
  .spec-list--two { grid-template-columns: 1fr 1fr; }
}

/* ============================================ METHOD ============================================ */
.method-pathway .method-arrow { stroke-dasharray: 200; stroke-dashoffset: 200; }
.method-pathway.animated .method-arrow { animation: arrowDraw 1.4s ease-out forwards; }
.method-pathway.animated .method-arrow:nth-of-type(2) { animation-delay: 0.3s; }
.method-pathway.animated .method-arrow:nth-of-type(3) { animation-delay: 0.6s; }
.method-pathway.animated .method-arrow:nth-of-type(4) { animation-delay: 0.9s; }
@keyframes arrowDraw { to { stroke-dashoffset: 0; } }

.method-step { opacity: 0; transform: scale(0.85); transform-origin: center; transform-box: fill-box; }
.method-pathway.animated .method-step { animation: stepIn 0.6s ease-out forwards; }
.method-pathway.animated .method-step[data-step="1"] { animation-delay: 0s; }
.method-pathway.animated .method-step[data-step="2"] { animation-delay: 0.4s; }
.method-pathway.animated .method-step[data-step="3"] { animation-delay: 0.8s; }
.method-pathway.animated .method-step[data-step="4"] { animation-delay: 1.2s; }
@keyframes stepIn { to { opacity: 1; transform: scale(1); } }

.method-step-card {
  padding: 1.4rem 1.5rem;
  border-left: 2px solid var(--line);
  transition: border-color .4s ease, padding-left .4s var(--ease-out-soft);
}
.method-step-card:hover {
  border-left-color: var(--cobalt);
  padding-left: 1.7rem;
}
.method-step-card--final { border-left-color: var(--cobalt); }

/* ============================================ ABOUT PORTRAIT (optional) ============================================ */
.about-portrait {
  width: 88px;
  height: 88px;
  border-radius: 999px;
  overflow: hidden;
  margin: 0 0 1.5rem;
  border: 1px solid var(--line);
  box-shadow: 0 12px 24px -12px rgba(15,30,54,0.22);
  background: var(--paper-soft);
}
.about-portrait img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
@media (min-width: 640px) {
  .about-portrait { width: 116px; height: 116px; }
}
@media (min-width: 1024px) {
  .about-portrait { width: 156px; height: 156px; }
}

/* ============================================ ABOUT CREDENTIALS ============================================ */
.about-creds {
  margin-top: 3rem;
  max-width: 42rem;
  padding: 1.75rem 1.9rem 1.9rem;
  border: 1px solid var(--line);
  border-left: 3px solid var(--cobalt);
  border-radius: 2px;
  background: var(--paper-soft);
}
.about-creds__head {
  font-size: 1.5rem;
  font-weight: 500;
  line-height: 1.15;
  letter-spacing: -0.01em;
  color: var(--navy);
  margin-bottom: 1.1rem;
}
@media (min-width: 640px) { .about-creds__head { font-size: 1.75rem; } }
.about-creds__list {
  display: grid;
  gap: 0.7rem;
  margin: 0;
  padding: 0;
  list-style: none;
}
.about-creds__list li {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--navy);
}
.about-creds__tick {
  flex: 0 0 auto;
  margin-top: 0.45rem;
  color: var(--cobalt);
}

/* ============================================ LESSON CARDS ============================================ */
.lesson-card {
  position: relative;
  padding: 1.75rem 1.6rem 1.9rem;
  background: var(--paper-soft);
  border: 1px solid var(--line);
  border-radius: 3px;
  transition: transform 0.4s ease, box-shadow 0.4s ease, border-color 0.4s ease;
}
.lesson-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 18px 36px -22px rgba(15,30,54,0.4);
  border-color: rgba(30,91,168,0.32);
}
.lesson-card__no {
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--cobalt);
  opacity: 0.85;
  margin-bottom: 0.85rem;
}
.lesson-card__title {
  font-size: 1.2rem;
  font-weight: 500;
  line-height: 1.2;
  color: var(--navy);
  margin-bottom: 0.6rem;
}
.lesson-card__body {
  font-size: 0.92rem;
  line-height: 1.6;
  color: rgba(15,30,54,0.7);
}

/* ============================================ LEGAL / TERMS PAGE ============================================ */
.legal-page { min-height: 70vh; }
.legal-section { margin-bottom: 2.5rem; }
.legal-head {
  font-size: 1.4rem;
  font-weight: 500;
  line-height: 1.25;
  color: var(--navy);
  padding-bottom: 0.6rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--line);
}
.legal-p {
  font-size: 1rem;
  line-height: 1.7;
  color: rgba(15,30,54,0.82);
  margin-bottom: 0.9rem;
}
.legal-p:last-child { margin-bottom: 0; }
.legal-sub {
  margin: 1.1rem 0 0;
  padding-left: 1.1rem;
  border-left: 2px solid var(--line);
}
.legal-subhead {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--cobalt);
  margin-bottom: 0.5rem;
}
.legal-cta {
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}

/* ============================================ PULL QUOTE ============================================ */
.pull-quote {
  position: relative;
  margin-top: 3rem;
  padding: 1.75rem 1.5rem 1.5rem 2rem;
  background: var(--paper-warm);
  border-left: 3px solid var(--cobalt);
  border-radius: 0 3px 3px 0;
}
.pull-quote__marker {
  position: absolute;
  top: -8px;
  left: 14px;
  font-family: var(--font-display);
  font-size: 4rem;
  line-height: 1;
  color: var(--cobalt);
  opacity: 0.3;
  pointer-events: none;
}

/* ============================================ TESTIMONIALS ============================================ */
.testimonial-card {
  position: relative;
  background: var(--paper-soft);
  padding: 2rem 1.75rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  overflow: hidden;
  transition: background-color .4s var(--ease-out-soft), border-color .4s var(--ease-out-soft), transform .4s var(--ease-out-soft);
}
@media (min-width: 640px) {
  .testimonial-card { padding: 2.5rem; }
}
.testimonial-card:hover {
  background: #FBF7EB;
  border-color: rgba(30,91,168,0.28);
  transform: translateY(-2px);
}
.testimonial-card__stars { color: var(--phosphorus); font-size: .9rem; letter-spacing: 2px; }
.testimonial-card__quote {
  margin: 1.25rem 0 0;
  font-family: var(--font-display);
  font-style: italic;
  font-weight: 300;
  font-size: 1.15rem;
  line-height: 1.45;
  color: var(--navy);
  max-width: 32rem;
}
@media (min-width: 640px) { .testimonial-card__quote { font-size: 1.25rem; } }
.testimonial-card__body {
  margin-top: 1.25rem;
  font-size: 0.88rem;
  color: rgba(15,30,54,0.65);
  line-height: 1.65;
  max-width: 32rem;
}
.testimonial-card__foot {
  margin-top: 1.75rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--ash-soft);
}
.testimonial-card__tag {
  position: absolute;
  top: 1.75rem;
  right: 1.75rem;
  font-family: var(--font-mono);
  font-size: 9.5px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--cobalt);
  opacity: 0.7;
}
@media (min-width: 640px) {
  .testimonial-card__tag { top: 2.5rem; right: 2.5rem; }
}

/* Grade reveal — 8 → 9 visual */
.grade-reveal {
  position: absolute;
  top: 1.4rem;
  right: 1.5rem;
  font-family: var(--font-display);
  color: var(--cobalt);
  opacity: 0.1;
  transition: opacity .6s ease;
}
.testimonial-card.is-visible .grade-reveal { animation: gradeReveal 1.2s 0.3s ease-out forwards; }
@keyframes gradeReveal { 0% { opacity: 0; transform: scale(0.9); } 100% { opacity: 0.14; transform: scale(1); } }
.grade-reveal__num {
  font-size: 4.5rem;
  line-height: 1;
  font-weight: 300;
  display: inline-flex;
  align-items: center;
  gap: .25rem;
}
@media (min-width: 640px) { .grade-reveal__num { font-size: 5.5rem; } }
.grade-reveal__arrow { display: inline-flex; color: var(--cobalt); opacity: 0.7; }
@media (max-width: 640px) { .grade-reveal { display: none; } }

/* ============================================ PRICE CARDS ============================================ */
.price-card {
  position: relative;
  background: var(--paper-soft);
  padding: 2.25rem 2rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  transition: background-color .45s var(--ease-out-soft), border-color .45s var(--ease-out-soft), transform .45s var(--ease-out-soft);
}
@media (min-width: 640px) {
  .price-card { padding: 3rem 2.5rem; }
}
.price-card:hover {
  background: #FBF7EB;
  border-color: rgba(30,91,168,0.32);
  transform: translateY(-2px);
}
.price-card__code {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--cobalt);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}
.price-card__price {
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(3rem, 7vw, 4.75rem);
  line-height: 1;
  color: var(--navy);
  letter-spacing: -0.02em;
}
.price-card__currency {
  font-size: 0.55em;
  vertical-align: 0.4em;
  color: var(--cobalt);
  margin-right: 2px;
}
.price-card__per {
  font-size: 0.32em;
  vertical-align: 0.3em;
  color: rgba(15,30,54,0.45);
  margin-left: 4px;
  font-family: var(--font-sans);
}
.price-card__list {
  margin-top: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  font-size: 0.92rem;
  color: rgba(15,30,54,0.7);
}
.price-card__list li {
  display: flex;
  align-items: flex-start;
  gap: .75rem;
  line-height: 1.5;
}
.price-card__list li::before {
  content: '';
  display: inline-block;
  flex-shrink: 0;
  margin-top: 9px;
  width: 14px; height: 1px;
  background: var(--cobalt);
}
.price-card--accent {
  background: var(--alkali-soft);
  border-color: rgba(30,91,168,0.28);
}
.price-card--accent:hover {
  background: #DCE6F4;
}

/* ============================================ FAQ ============================================ */
.faq-list {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.faq-item {
  border-bottom: 1px solid var(--line);
  padding: 0;
  transition: background-color .35s ease;
}
.faq-item:last-child { border-bottom: 0; }
.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.5rem 0;
  cursor: pointer;
  list-style: none;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-q {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--navy);
  letter-spacing: -0.01em;
}
@media (min-width: 640px) { .faq-q { font-size: 1.25rem; } }
.faq-marker {
  color: var(--cobalt);
  display: inline-flex;
  align-items: center;
  transition: transform .4s var(--ease-out-soft);
}
.faq-item[open] .faq-marker { transform: rotate(90deg); }
.faq-a {
  padding: 0 0 1.5rem;
  color: rgba(15,30,54,0.7);
  line-height: 1.65;
  max-width: 56ch;
}
.faq-item[open] { background: rgba(30,91,168,0.025); }

/* ============================================ FORM ============================================ */
.booking-step__legend {
  display: flex;
  align-items: center;
  gap: .75rem;
  margin-bottom: 1.5rem;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--cobalt);
  text-transform: uppercase;
  letter-spacing: 0.22em;
}
.form-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 10.5px;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--ash);
}
.form-input {
  display: block;
  width: 100%;
  margin-top: 10px;
  background: transparent;
  border: 0;
  border-bottom: 1px solid rgba(15,30,54,0.18);
  color: var(--navy);
  font-family: var(--font-sans);
  font-size: 1rem;
  padding: 12px 0;
  transition: border-color .25s ease, color .25s ease;
  outline: none;
  border-radius: 0;
}
.form-input:focus { border-color: var(--cobalt); outline: none; }
.form-input::placeholder { color: rgba(15,30,54,0.32); }
.form-input:focus-visible { outline: none; box-shadow: inset 0 -2px 0 0 var(--cobalt); border-bottom-color: var(--cobalt); }

select.form-input {
  appearance: none;
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%231E5BA8' stroke-width='1.2' fill='none'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 4px center;
  padding-right: 24px;
  cursor: pointer;
}
select.form-input option { background: var(--paper-soft); color: var(--navy); }

textarea.form-input { resize: vertical; min-height: 96px; }

.chip {
  display: inline-flex;
  align-items: center;
  padding: 8px 16px;
  border: 1px solid rgba(15,30,54,0.18);
  border-radius: 999px;
  font-size: 0.875rem;
  color: var(--navy);
  cursor: pointer;
  transition: all .22s ease;
  user-select: none;
  background: var(--paper-soft);
}
.chip input { position: absolute; opacity: 0; pointer-events: none; }
.chip:hover { border-color: var(--cobalt); color: var(--cobalt); }
.chip:has(input:checked) {
  background: var(--cobalt);
  border-color: var(--cobalt);
  color: var(--paper-soft);
  font-weight: 500;
}

/* ============================================ PERIODIC TABLE ============================================ */
#periodic-table {
  display: grid;
  grid-template-columns: repeat(18, minmax(0, 1fr));
  gap: 2px;
  max-width: 100%;
  overflow-x: auto;
  padding-bottom: 8px;
}
@media (max-width: 768px) {
  #periodic-table { min-width: 880px; }
  #elements .overflow-x { overflow-x: auto; }
}

.pt-cell {
  position: relative;
  aspect-ratio: 1;
  background: var(--paper-soft);
  border: 1px solid rgba(15,30,54,0.08);
  font-family: var(--font-sans);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2px;
  cursor: default;
  color: var(--navy);
  transition: all .25s ease;
  min-width: 0;
  border-radius: 2px;
}
.pt-cell.has-note {
  cursor: pointer;
  background: var(--cobalt);
  color: var(--paper-soft);
  border-color: var(--cobalt);
}
.pt-cell.has-note:hover {
  background: var(--navy);
  color: var(--cobalt-bright);
  transform: scale(1.08);
  z-index: 2;
  box-shadow: 0 6px 16px -8px rgba(15,30,54,0.4);
}
.pt-cell.empty { background: transparent; border: none; pointer-events: none; }
.pt-cell .num {
  font-size: 8px;
  opacity: 0.5;
  line-height: 1;
  position: absolute;
  top: 3px; left: 4px;
  font-family: var(--font-mono);
}
.pt-cell .sym { font-size: 14px; font-weight: 500; line-height: 1; }
.pt-cell .name {
  font-size: 7px;
  opacity: 0.55;
  margin-top: 2px;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}
@media (min-width: 1024px) {
  .pt-cell .sym { font-size: 16px; }
  .pt-cell .name { font-size: 8px; }
}

#element-tooltip {
  border-top: 2px solid var(--cobalt);
  animation: tooltipIn .3s ease-out;
}
@keyframes tooltipIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

/* ============================================ MOBILE TUNING ============================================ */
@media (max-width: 1023px) {
  .hero-art {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  .hero-art .benzene-svg {
    position: relative;
    width: auto;
    height: 100%;
    max-height: 100%;
    max-width: 320px;
    opacity: 1;
  }
  section.hero-section { padding-top: 5rem; }
}
@media (max-width: 640px) {
  .hero-title { letter-spacing: -0.02em; }
  .hero-art .benzene-svg { max-width: 240px; }
  .rx-btn { font-size: 0.85rem; padding: 0.95rem 1.35rem; }
  .equation-divider { font-size: 0.65rem; padding: 1.75rem 1.25rem; gap: 0.65rem 1rem; }
}

/* ============================================ REDUCED MOTION ============================================ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .benzene-rotate { animation: none; }
  .reveal { opacity: 1; transform: none; }
  .examined-badge__dot { animation: none; }
}