/* ── Reset & Variables ───────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --ink:       #0f1117;
  --ink-soft:  #3d4154;
  --ink-muted: #7c8099;
  --bg:        #fafaf8;
  --bg-card:   #ffffff;
  --bg-subtle: #f4f4f0;
  --accent:    #2563eb;
  --accent-lt: #dbeafe;
  --green:     #16a34a;
  --green-lt:  #dcfce7;
  --border:    #e4e4dc;
  --radius:    12px;
  --radius-sm: 7px;
  --shadow:    0 1px 3px rgba(0,0,0,.06), 0 4px 16px rgba(0,0,0,.06);
  --shadow-lg: 0 8px 32px rgba(0,0,0,.10);
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: 'Space Grotesk', sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: 'Fraunces', serif;
  line-height: 1.2;
  font-weight: 700;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* ── Header ─────────────────────────────────────────────── */
.site-header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 50;
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 3.5rem;
}
.logo {
  display: flex; align-items: center; gap: .5rem;
  font-family: 'Fraunces', serif;
  font-size: 1.25rem; font-weight: 700;
  color: var(--ink); text-decoration: none;
}
.logo-icon { font-size: 1.5rem; }
.site-nav { display: flex; gap: 1.5rem; }
.site-nav a { color: var(--ink-soft); font-weight: 500; font-size: .9rem; }
.site-nav a:hover { color: var(--accent); text-decoration: none; }

/* ── Hero ────────────────────────────────────────────────── */
.hero {
  background: linear-gradient(135deg, #1e3a8a 0%, #1d4ed8 50%, #3b82f6 100%);
  color: #fff;
  padding: 3.5rem 0 3rem;
  text-align: center;
}
.hero-label {
  display: inline-block;
  background: rgba(255,255,255,.15);
  border: 1px solid rgba(255,255,255,.25);
  border-radius: 99px;
  padding: .2rem .85rem;
  font-size: .78rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  color: #fff;
  margin-bottom: .75rem;
}
.hero-sub {
  color: rgba(255,255,255,.85);
  font-size: 1.05rem;
  max-width: 520px;
  margin: 0 auto;
}

/* ── Calculator Card ─────────────────────────────────────── */
.calc-section { padding: 2.5rem 0 3rem; }
.calc-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 2rem 2rem 1.5rem;
  max-width: 760px;
  margin: 0 auto;
}

.calc-inputs {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: end;
  gap: 1.25rem;
}
@media (max-width: 620px) {
  .calc-inputs { grid-template-columns: 1fr; }
}

.fraction-input-group label {
  display: block;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: .5rem;
}

.fraction-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}
.fraction-box input {
  width: 100%;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .6rem .75rem;
  font-size: 1.3rem;
  font-family: 'Fraunces', serif;
  text-align: center;
  color: var(--ink);
  outline: none;
  transition: border-color .15s;
}
.fraction-box input:focus { border-color: var(--accent); }
.fraction-bar {
  width: 100%;
  height: 3px;
  background: var(--ink);
  border-radius: 2px;
  margin: 2px 0;
}

.op-group { text-align: center; }
.op-group label {
  display: block;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: .5rem;
}
.op-buttons {
  display: flex;
  flex-direction: column;
  gap: .35rem;
}
.op-btn {
  width: 52px;
  height: 36px;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-subtle);
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all .15s;
  color: var(--ink-soft);
}
.op-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  box-shadow: 0 2px 8px rgba(37,99,235,.3);
}
.op-btn:hover:not(.active) {
  border-color: var(--accent);
  color: var(--accent);
}
.op-simplify { font-size: .65rem !important; width: 52px; padding: 0 4px; }

.calc-actions {
  display: flex;
  gap: .75rem;
  margin-top: 1.5rem;
  justify-content: center;
}
.btn-calculate {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  padding: .7rem 2.5rem;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background .15s, transform .1s;
  font-family: 'Space Grotesk', sans-serif;
}
.btn-calculate:hover { background: #1d4ed8; }
.btn-calculate:active { transform: scale(.97); }
.btn-clear {
  background: var(--bg-subtle);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .7rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--ink-soft);
  font-family: 'Space Grotesk', sans-serif;
}

/* ── Result Area ─────────────────────────────────────────── */
.result-area { margin-top: 1.75rem; }
.result-card {
  background: linear-gradient(135deg, #f0f7ff 0%, #e0f2fe 100%);
  border: 1.5px solid #bfdbfe;
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}
.result-label {
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .07em;
  text-transform: uppercase;
  color: var(--accent);
}
.result-fraction {
  font-family: 'Fraunces', serif;
  font-size: 2rem;
  font-weight: 700;
  color: var(--ink);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1px;
}
.result-fraction .rf-num,
.result-fraction .rf-den { line-height: 1; }
.result-fraction .rf-bar {
  width: 100%;
  height: 3px;
  background: var(--ink);
}
.result-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}
.result-meta span {
  background: #fff;
  border: 1px solid #bfdbfe;
  border-radius: 6px;
  padding: .2rem .65rem;
  font-size: .82rem;
  color: var(--ink-soft);
}

.steps-card {
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin-top: .85rem;
}
.steps-card h3 { font-size: .9rem; margin-bottom: .85rem; }
.steps-list { padding-left: 1.4rem; }
.steps-list li {
  color: var(--ink-soft);
  font-size: .88rem;
  margin-bottom: .4rem;
  padding-left: .25rem;
}
.steps-list li strong { color: var(--ink); }

.permalink-bar {
  display: flex;
  align-items: center;
  gap: .6rem;
  margin-top: .85rem;
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
  padding: .6rem 1rem;
  font-size: .82rem;
  flex-wrap: wrap;
}
.permalink-bar a {
  color: var(--accent);
  word-break: break-all;
}
.copy-btn {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 5px;
  padding: .2rem .7rem;
  font-size: .78rem;
  cursor: pointer;
  font-family: 'Space Grotesk', sans-serif;
}
.error-msg {
  background: #fef2f2;
  border: 1.5px solid #fca5a5;
  color: #dc2626;
  border-radius: var(--radius-sm);
  padding: .75rem 1rem;
  margin-top: 1rem;
  font-size: .88rem;
}

/* ── How To Section ──────────────────────────────────────── */
.how-section { background: var(--bg-subtle); padding: 3.5rem 0; }
.how-section h2 {
  font-size: 1.85rem;
  text-align: center;
  margin-bottom: 2rem;
}
.how-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 1.25rem;
}
.how-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 1.5rem;
  border: 1.5px solid var(--border);
  transition: box-shadow .2s;
}
.how-card:hover { box-shadow: var(--shadow); }
.how-icon { font-size: 1.75rem; margin-bottom: .75rem; }
.how-card h3 { font-size: 1rem; margin-bottom: .5rem; }
.how-card p { font-size: .87rem; color: var(--ink-soft); margin-bottom: .85rem; }
.how-card a { font-size: .82rem; font-weight: 600; }

/* ── Popular Section ─────────────────────────────────────── */
.popular-section { padding: 3rem 0; }
.popular-section h2 { font-size: 1.85rem; margin-bottom: 1.5rem; }
.popular-grid {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
}
.popular-link {
  display: inline-block;
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: 99px;
  padding: .35rem 1rem;
  font-size: .85rem;
  font-weight: 600;
  color: var(--ink);
  transition: all .15s;
}
.popular-link:hover {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
}

/* ── FAQ ─────────────────────────────────────────────────── */
.faq-section { background: var(--bg-subtle); padding: 3.5rem 0; }
.faq-section h2 { font-size: 1.85rem; margin-bottom: 2rem; }
.faq-list { max-width: 740px; display: flex; flex-direction: column; gap: .75rem; }
.faq-item {
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.faq-item summary {
  padding: 1rem 1.25rem;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.faq-item summary::after { content: '+'; font-size: 1.25rem; color: var(--accent); }
.faq-item[open] summary::after { content: '−'; }
.faq-item p {
  padding: 0 1.25rem 1rem;
  color: var(--ink-soft);
  font-size: .9rem;
}

/* ── Fraction Result Page ────────────────────────────────── */
.frac-hero {
  background: var(--bg-subtle);
  border-bottom: 1.5px solid var(--border);
  padding: 1.75rem 0 1.25rem;
}
.breadcrumb {
  display: flex;
  align-items: center;
  gap: .4rem;
  font-size: .82rem;
  color: var(--ink-muted);
  margin-bottom: .5rem;
}
.breadcrumb a { color: var(--ink-muted); }
.breadcrumb a:hover { color: var(--accent); }
.frac-hero h1 { font-size: clamp(1.5rem, 3vw, 2.5rem); }

.frac-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 2rem;
  padding-top: 2rem;
  padding-bottom: 3rem;
  align-items: start;
}
@media (max-width: 860px) {
  .frac-layout { grid-template-columns: 1fr; }
}

.answer-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
}
.answer-problem {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
}
.frac-display {
  font-family: 'Fraunces', serif;
  font-size: 1.5rem;
  color: var(--ink-soft);
}
.op-sym { font-size: 1.75rem; font-weight: 700; color: var(--ink); }
.equals-sym {
  font-family: 'Fraunces', serif;
  font-size: 2rem;
  color: var(--ink-muted);
}
.frac-result-big {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
}
.frac-num, .frac-den {
  font-family: 'Fraunces', serif;
  font-size: 2.5rem;
  font-weight: 700;
  line-height: 1;
  color: var(--green);
}
.frac-bar-big {
  width: 100%;
  height: 4px;
  background: var(--green);
  border-radius: 2px;
  margin: 3px 0;
}
.whole-result {
  font-family: 'Fraunces', serif;
  font-size: 3rem;
  font-weight: 700;
  color: var(--green);
}

.answer-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}
.meta-tag {
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
  padding: .35rem .85rem;
  font-size: .85rem;
  display: flex;
  gap: .4rem;
  align-items: center;
}
.meta-label { color: var(--ink-muted); }

.steps-section { margin-bottom: 1.5rem; }
.steps-section h2 { font-size: 1.2rem; margin-bottom: 1rem; }
.steps-ol { list-style: none; padding: 0; display: flex; flex-direction: column; gap: .75rem; }
.step-item {
  display: flex;
  gap: 1rem;
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  align-items: flex-start;
}
.step-num {
  width: 28px; height: 28px;
  background: var(--accent);
  color: #fff;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: .8rem; font-weight: 700;
  flex-shrink: 0;
}
.step-label { font-weight: 600; font-size: .9rem; margin-bottom: .2rem; }
.step-detail { font-size: .87rem; color: var(--ink-soft); font-family: 'Fraunces', serif; }

.explanation-section {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 1.5rem;
  border: 1.5px solid var(--border);
  margin-bottom: 1.5rem;
}
.explanation-section h2 { font-size: 1.1rem; margin-bottom: .65rem; }
.explanation-section p { font-size: .9rem; color: var(--ink-soft); }

.try-calc-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 1.5rem;
  border: 1.5px solid var(--border);
}
.try-calc-card h3 { font-size: 1rem; margin-bottom: 1rem; }
.mini-calc .calc-inputs { gap: .85rem; }
.mini-calc .fraction-box input { font-size: 1.1rem; padding: .45rem .5rem; }

/* ── Sidebar ─────────────────────────────────────────────── */
.sidebar-card {
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 1rem;
}
.sidebar-card h3 { font-size: .95rem; margin-bottom: .85rem; }
.related-list { list-style: none; padding: 0; display: flex; flex-direction: column; gap: .35rem; }
.related-list a {
  display: flex;
  flex-direction: column;
  background: var(--bg-subtle);
  border-radius: var(--radius-sm);
  padding: .5rem .75rem;
  text-decoration: none;
  transition: background .15s;
}
.related-list a:hover { background: var(--accent-lt); }
.rel-label { font-family: 'Fraunces', serif; font-weight: 600; font-size: .9rem; color: var(--ink); }
.rel-desc { font-size: .75rem; color: var(--ink-muted); }
.sidebar-tip { background: #fffbeb; border-color: #fde68a; }
.sidebar-tip h3 { color: #92400e; }
.sidebar-tip p { font-size: .85rem; color: #78350f; }

/* ── Footer ─────────────────────────────────────────────── */
.site-footer {
  background: var(--ink);
  color: rgba(255,255,255,.7);
  padding: 3rem 0 1.5rem;
  margin-top: 2rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}
@media (max-width: 640px) {
  .footer-grid { grid-template-columns: 1fr; }
}
.footer-brand {
  font-family: 'Fraunces', serif;
  font-size: 1.2rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: .5rem;
}
.site-footer p { font-size: .87rem; }
.site-footer h4 {
  font-size: .8rem;
  letter-spacing: .07em;
  text-transform: uppercase;
  color: rgba(255,255,255,.4);
  margin-bottom: .75rem;
}
.site-footer ul { list-style: none; display: flex; flex-direction: column; gap: .35rem; }
.site-footer ul a {
  color: rgba(255,255,255,.65);
  font-size: .87rem;
}
.site-footer ul a:hover { color: #fff; text-decoration: none; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.1);
  padding-top: 1.25rem;
  font-size: .82rem;
  color: rgba(255,255,255,.4);
}
.footer-bottom a { color: rgba(255,255,255,.5); }

/* ── Responsive tweaks ──────────────────────────────────── */
@media (max-width: 620px) {
  .calc-card { padding: 1.25rem; }
  .op-buttons { flex-direction: row; flex-wrap: wrap; justify-content: center; }
  .op-btn { width: 44px; height: 34px; }
  .answer-problem { gap: .75rem; }
}