/* CalcFriendly — shared styles
   Palette: graph paper + ink + LCD readout + calculator "=" key */
:root {
  --paper: #f6f8f7;
  --grid: #e2ebe8;
  --panel: #ffffff;
  --ink: #14233b;
  --muted: #55667a;
  --line: #c8d5d1;
  --link: #1b5e8c;
  --lcd: #1e3b33;
  --lcd-text: #d7f5c0;
  --lcd-dim: #8fb79c;
  --key: #f6c423;
  --key-dark: #d9a90c;
  --warn: #9a3b12;
  --radius: 14px;
  --font-display: "Bricolage Grotesque", "Segoe UI", system-ui, sans-serif;
  --font-body: "Atkinson Hyperlegible", "Segoe UI", system-ui, sans-serif;
  --font-lcd: "IBM Plex Mono", ui-monospace, Consolas, monospace;
  --wrap: 1120px;
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.6;
}

img, svg { max-width: 100%; display: block; }

[hidden] { display: none !important; }

.lcd-link { color: var(--lcd-text); }
.lcd-link:hover { color: #ffffff; }

a { color: var(--link); text-underline-offset: 3px; }
a:hover { color: var(--ink); }

:focus-visible {
  outline: 3px solid var(--link);
  outline-offset: 2px;
  border-radius: 4px;
}

.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 16px;
}

.skip {
  position: absolute;
  left: -9999px;
}
.skip:focus {
  left: 16px;
  top: 12px;
  background: var(--panel);
  padding: 8px 12px;
  z-index: 10;
}

/* ---------- Graph paper ---------- */
.graph {
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  background-position: -1px -1px;
}

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1.5px solid var(--ink);
  background: var(--panel);
}
.site-header .wrap {
  display: flex;
  align-items: center;
  gap: 24px;
  min-height: 64px;
  flex-wrap: wrap;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.35rem;
  letter-spacing: -0.02em;
  color: var(--ink);
  text-decoration: none;
}
.brand-mark {
  width: 30px;
  height: 30px;
  flex: none;
}
.site-nav {
  display: flex;
  gap: 4px;
  margin-left: auto;
  overflow-x: auto;
  scrollbar-width: none;
}
.site-nav a {
  padding: 6px 12px;
  border-radius: 999px;
  color: var(--ink);
  text-decoration: none;
  font-weight: 700;
  font-size: 0.95rem;
  white-space: nowrap;
}
.site-nav a:hover { background: var(--grid); }
.site-nav a[aria-current="page"] { background: var(--ink); color: var(--panel); }

@media (max-width: 720px) {
  .site-header .wrap { gap: 4px; padding-top: 10px; }
  .site-nav { margin: 0 -16px; padding: 4px 16px 10px; width: calc(100% + 32px); }
}

/* ---------- Type ---------- */
h1, h2, h3 {
  font-family: var(--font-display);
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 0 0.5em;
}
h1 { font-size: clamp(2rem, 5vw, 3.1rem); font-weight: 800; }
h2 { font-size: clamp(1.45rem, 3vw, 1.9rem); font-weight: 700; margin-top: 1.8em; }
h3 { font-size: 1.2rem; font-weight: 700; margin-top: 1.5em; }
p { margin: 0 0 1em; }
.lede { font-size: 1.2rem; color: var(--muted); max-width: 60ch; }

/* ---------- Home hero ---------- */
.hero { border-bottom: 1.5px solid var(--ink); }
.hero .wrap {
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 48px;
  align-items: center;
  padding-top: 64px;
  padding-bottom: 64px;
}
.hero h1 {
  font-size: clamp(2.4rem, 6vw, 4.2rem);
  line-height: 1.02;
  max-width: 13ch;
}
.hero .lede { margin-bottom: 1.4em; }
.hero-points {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  color: var(--muted);
  font-size: 0.98rem;
}
.hero-points li::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  margin-right: 8px;
  background: var(--key);
  border: 1.5px solid var(--ink);
  border-radius: 2px;
  vertical-align: 1px;
}
@media (max-width: 860px) {
  .hero .wrap { grid-template-columns: 1fr; gap: 32px; padding-top: 40px; padding-bottom: 40px; }
}

/* ---------- Tool panel ---------- */
.tool {
  background: var(--panel);
  border: 1.5px solid var(--ink);
  border-radius: var(--radius);
  box-shadow: 0 5px 0 var(--ink);
  overflow: hidden;
}
.tool + .tool { margin-top: 28px; }
.tool-title {
  margin: 0;
  padding: 14px 20px;
  font-size: 1.05rem;
  border-bottom: 1.5px solid var(--ink);
  background: var(--paper);
}
.tool-body {
  display: grid;
  grid-template-columns: 1fr 1fr;
}
.tool-body.stack { grid-template-columns: 1fr; }
.tool-inputs {
  padding: 20px;
  display: grid;
  gap: 16px;
  align-content: start;
}
@media (max-width: 760px) {
  .tool-body { grid-template-columns: 1fr; }
}

.field { display: grid; gap: 6px; }
.field label, .field .label {
  font-weight: 700;
  font-size: 0.95rem;
}
.field small { color: var(--muted); font-size: 0.85rem; }
.row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.row-3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 12px; }
@media (max-width: 420px) {
  .row-3 { grid-template-columns: 1fr 1fr; }
}

input[type="number"], input[type="date"], input[type="text"], select {
  width: 100%;
  min-height: 46px;
  padding: 10px 12px;
  font: inherit;
  font-size: 1.05rem;
  color: var(--ink);
  background: var(--panel);
  border: 1.5px solid var(--line);
  border-radius: 10px;
}
input:hover, select:hover { border-color: var(--muted); }
input:focus, select:focus { border-color: var(--ink); outline: 3px solid rgba(27, 94, 140, 0.25); outline-offset: 0; }
input[type="number"] { font-variant-numeric: tabular-nums; }

.input-unit { position: relative; }
.input-unit input { padding-right: 52px; }
.input-unit span {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  font-size: 0.92rem;
  pointer-events: none;
}

.segmented {
  display: inline-flex;
  border: 1.5px solid var(--ink);
  border-radius: 10px;
  overflow: hidden;
  width: fit-content;
}
.segmented label {
  position: relative;
  font-weight: 700;
  font-size: 0.92rem;
}
.segmented input { position: absolute; opacity: 0; inset: 0; cursor: pointer; }
.segmented span { display: block; padding: 8px 14px; cursor: pointer; }
.segmented label + label span { border-left: 1.5px solid var(--ink); }
.segmented input:checked + span { background: var(--ink); color: var(--panel); }
.segmented input:focus-visible + span { outline: 3px solid var(--link); outline-offset: -3px; }

.check { display: flex; gap: 10px; align-items: center; font-size: 0.98rem; }
.check input { width: 20px; height: 20px; accent-color: var(--ink); }

/* Calculator key buttons */
.key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 8px 18px;
  font: inherit;
  font-weight: 700;
  color: var(--ink);
  background: var(--key);
  border: 1.5px solid var(--ink);
  border-radius: 10px;
  box-shadow: 0 3px 0 var(--ink);
  cursor: pointer;
  text-decoration: none;
  transition: transform 80ms ease, box-shadow 80ms ease;
}
.key:hover { background: #ffd23f; color: var(--ink); }
.key:active { transform: translateY(3px); box-shadow: 0 0 0 var(--ink); }
.key.plain { background: var(--panel); }
.key.plain:hover { background: var(--grid); }
.key.small { min-height: 36px; padding: 4px 12px; font-size: 0.92rem; }

/* ---------- LCD readout ---------- */
.readout {
  background: var(--lcd);
  color: var(--lcd-text);
  padding: 22px 22px 24px;
  display: grid;
  gap: 18px;
  align-content: start;
}
.tool-body:not(.stack) .readout { border-left: 1.5px solid var(--ink); }
.tool-body.stack .readout, .readout.below { border-top: 1.5px solid var(--ink); }
@media (max-width: 760px) {
  .tool-body:not(.stack) .readout { border-left: 0; border-top: 1.5px solid var(--ink); }
}
.readout-main .rlabel, .readout-grid .rlabel {
  display: block;
  color: var(--lcd-dim);
  font-size: 0.88rem;
}
.readout-main output {
  display: block;
  font-family: var(--font-lcd);
  font-weight: 500;
  font-size: clamp(2rem, 5vw, 2.8rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  word-break: break-word;
  font-variant-numeric: tabular-nums;
}
.readout-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 14px 18px;
  padding-top: 16px;
  border-top: 1px solid rgba(215, 245, 192, 0.2);
}
.readout-grid output {
  display: block;
  font-family: var(--font-lcd);
  font-size: 1.15rem;
  font-variant-numeric: tabular-nums;
  word-break: break-word;
}
.readout .note {
  margin: 0;
  font-size: 0.92rem;
  color: var(--lcd-dim);
}
.readout .note:empty { display: none; }
.readout .tag {
  display: inline-block;
  margin-top: 6px;
  padding: 2px 10px;
  border-radius: 999px;
  background: var(--lcd-text);
  color: var(--lcd);
  font-weight: 700;
  font-size: 0.92rem;
}
.readout .tag:empty { display: none; }

.flash { animation: flash 260ms steps(2, end); }
@keyframes flash { 50% { opacity: 0.35; } }

/* Tables inside tools and articles */
.table-scroll { overflow-x: auto; }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
  font-variant-numeric: tabular-nums;
}
th, td { padding: 8px 10px; text-align: right; border-bottom: 1px solid var(--line); }
th:first-child, td:first-child { text-align: left; }
thead th { font-family: var(--font-display); border-bottom: 1.5px solid var(--ink); }
.tool-table { padding: 0 20px 20px; }
.tool-table h3 { margin-top: 20px; }
.readout table th, .readout table td { border-color: rgba(215, 245, 192, 0.2); }
.readout table thead th { border-color: var(--lcd-dim); }

/* GPA rows */
.course-list { display: grid; gap: 10px; }
.course {
  display: grid;
  grid-template-columns: 1.6fr 0.8fr 0.9fr auto;
  gap: 8px;
  align-items: center;
}
.course .remove {
  width: 40px;
  height: 46px;
  border: 1.5px solid var(--line);
  border-radius: 10px;
  background: var(--panel);
  color: var(--muted);
  font-size: 1.3rem;
  cursor: pointer;
}
.course .remove:hover { border-color: var(--warn); color: var(--warn); }
.course-head { color: var(--muted); font-size: 0.85rem; font-weight: 700; }
@media (max-width: 480px) {
  .course { grid-template-columns: 1fr 0.7fr 0.8fr auto; }
}

/* ---------- Tool page layout ---------- */
.page-head { padding: 36px 0 32px; border-bottom: 1.5px solid var(--ink); }
.crumbs {
  font-size: 0.92rem;
  color: var(--muted);
  margin-bottom: 14px;
}
.crumbs a { color: var(--muted); }
.crumbs span[aria-hidden] { margin: 0 6px; }
.page-head .lede { margin-bottom: 0; }

.tool-zone { padding: 36px 0 44px; }

.article-zone {
  border-top: 1.5px solid var(--ink);
  background: var(--panel);
  padding: 8px 0 56px;
}
.article-grid {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 56px;
}
.toc {
  position: sticky;
  top: 20px;
  align-self: start;
  padding-top: 40px;
  font-size: 0.95rem;
}
.toc p { font-weight: 700; margin-bottom: 8px; }
.toc ol { list-style: none; padding: 0; margin: 0; display: grid; gap: 6px; }
.toc a { color: var(--muted); text-decoration: none; }
.toc a:hover { color: var(--ink); text-decoration: underline; }
@media (max-width: 900px) {
  .article-grid { grid-template-columns: 1fr; gap: 0; }
  .toc { position: static; padding-top: 28px; }
}

.prose { max-width: 70ch; }
.prose h2 { scroll-margin-top: 20px; }
.prose ul, .prose ol { padding-left: 1.3em; margin: 0 0 1em; }
.prose li { margin-bottom: 0.35em; }
.prose table { margin: 0 0 1.4em; }
.formula {
  margin: 0 0 1.2em;
  padding: 14px 18px;
  background: var(--paper);
  border-left: 4px solid var(--key);
  border-radius: 0 10px 10px 0;
  font-family: var(--font-lcd);
  font-size: 0.98rem;
  overflow-x: auto;
}
.example {
  margin: 0 0 1.4em;
  padding: 16px 18px;
  border: 1.5px solid var(--line);
  border-radius: 12px;
}
.example p:last-child { margin-bottom: 0; }
.callout {
  margin: 0 0 1.4em;
  padding: 14px 18px;
  background: #fff8dc;
  border: 1.5px solid var(--key-dark);
  border-radius: 12px;
  font-size: 0.98rem;
}
.callout p:last-child { margin: 0; }

.faq details {
  border-bottom: 1px solid var(--line);
  padding: 12px 0;
}
.faq summary {
  cursor: pointer;
  font-weight: 700;
  font-family: var(--font-display);
  font-size: 1.08rem;
}
.faq details p { margin: 10px 0 0; }

.related { padding: 44px 0 56px; border-top: 1.5px solid var(--ink); }
.related h2 { margin-top: 0; }

/* ---------- Calculator index (home + all) ---------- */
.index { padding: 56px 0 64px; }
.index > .wrap > h2 { margin-top: 0; }
.index-groups {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 36px 40px;
  margin-top: 28px;
}
.index-group h3 {
  margin: 0 0 10px;
  padding-bottom: 8px;
  border-bottom: 1.5px solid var(--ink);
  display: flex;
  align-items: center;
  gap: 10px;
}
.index-group h3 svg { width: 22px; height: 22px; }
.index-list { list-style: none; margin: 0; padding: 0; }
.index-list li { border-bottom: 1px solid var(--line); }
.index-list a {
  display: block;
  padding: 12px 0;
  text-decoration: none;
  color: var(--ink);
}
.index-list a strong { display: block; font-size: 1.05rem; }
.index-list a span { display: block; color: var(--muted); font-size: 0.93rem; line-height: 1.45; }
.index-list a:hover strong { text-decoration: underline; text-decoration-color: var(--key-dark); text-decoration-thickness: 3px; }

.promise {
  border-top: 1.5px solid var(--ink);
  background: var(--panel);
  padding: 56px 0;
}
.promise-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 28px 40px;
}
.promise h2 { margin-top: 0; }
.promise h3 { margin-top: 0; }
.promise p { color: var(--muted); }

/* ---------- Plain pages ---------- */
.plain { padding: 40px 0 64px; background: var(--panel); }
.plain .prose { margin: 0; }

/* ---------- Footer ---------- */
.site-footer {
  background: var(--ink);
  color: #c9d3df;
  padding: 44px 0 32px;
  font-size: 0.95rem;
}
.site-footer a { color: #ffffff; }
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr repeat(3, 1fr);
  gap: 28px;
}
.footer-grid h2 {
  font-size: 1rem;
  margin: 0 0 10px;
  color: #ffffff;
}
.footer-grid ul { list-style: none; padding: 0; margin: 0; display: grid; gap: 6px; }
.footer-brand { color: #ffffff; }
.footer-bottom {
  margin-top: 32px;
  padding-top: 18px;
  border-top: 1px solid rgba(255, 255, 255, 0.15);
}
@media (max-width: 760px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-grid > div:first-child { grid-column: 1 / -1; }
}

/* Ad slots: invisible until AdSense fills them */
.ad-slot { margin: 28px 0; min-height: 0; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}