/* ===========================================================
   RREF Calculator — styles
   =========================================================== */

:root {
  --c-primary:      #15803D;   /* green */
  --c-primary-dark: #13642F;
  --c-primary-lite: #1E9A4E;
  --c-soft:         #E3F3E8;
  --c-bg:           #F1F2F3;
  --c-box:          #FAFAFA;
  --c-border:       #C9C9C9;
  --c-text:         #1a1a1a;
  --c-muted:        #555;
  --c-var:          #E8870B;   /* orange A */
  --wrap:           1180px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 15px;
  line-height: 1.55;
}

a { color: var(--c-primary); }

.wrap {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- header ---------- */
.site-header .bar-main { background: var(--c-primary); }
.site-header .bar-sub  { background: var(--c-primary-dark); }

.site-header .bar-main .wrap {
  display: flex;
  align-items: center;
  gap: 26px;
  min-height: 48px;
}
.brand { display: flex; align-items: center; gap: 9px; text-decoration: none; color: #fff; }
.brand-mark {
  display: grid; place-items: center;
  width: 30px; height: 30px;
  border-radius: 6px;
  background: rgba(255,255,255,0.16);
  font-family: 'PT Serif', serif; font-weight: 700; font-size: 15px;
}
.brand-name { font-family: 'PT Serif', serif; font-weight: 700; font-size: 17px; }

.nav-main { display: flex; gap: 30px; margin: 0 auto; }
.nav-main a { color: #fff; text-decoration: none; font-size: 13px; letter-spacing: 0.04em; font-weight: 500; }
.nav-main a:hover { text-decoration: underline; }

.nav-sub { display: flex; gap: 22px; justify-content: center; flex-wrap: wrap; padding: 9px 20px; }
.nav-sub a { color: rgba(255,255,255,0.92); text-decoration: none; font-size: 13px; }
.nav-sub a:hover { color: #fff; text-decoration: underline; }

/* ---------- page ---------- */
.page { padding-top: 18px; padding-bottom: 60px; }

.breadcrumb { font-size: 14px; color: var(--c-muted); margin-bottom: 14px; }
.breadcrumb a { text-decoration: none; }
.breadcrumb span { color: #aaa; }
.breadcrumb .current { color: var(--c-muted); }

.page-title {
  text-align: center;
  font-family: 'PT Serif', serif;
  font-weight: 700;
  font-size: 33px;
  margin: 14px 0 6px;
}
.title-rule {
  width: 300px; height: 0;
  border-bottom: 2px dotted #b7b7b7;
  margin: 0 auto 12px;
}
.page-subtitle { text-align: center; color: #777; font-size: 18px; margin: 0 0 24px; }

/* ---------- boxes ---------- */
.box {
  background: var(--c-box);
  border: 1px solid var(--c-border);
  border-radius: 3px;
  padding: 22px 26px;
  margin-bottom: 22px;
}
.box p { margin: 0 0 14px; }
.box p:last-child { margin-bottom: 0; }
.muted { color: var(--c-muted); }

/* ---------- calculator ---------- */
.calculator { padding: 26px 30px; }
.label { font-weight: 700; }

.size-row {
  display: flex; align-items: center; gap: 12px;
  flex-wrap: wrap; margin-bottom: 22px;
}
.size-row input {
  width: 150px; padding: 7px 10px; font-size: 15px;
  border: 1px solid #B8B8B8; border-radius: 3px; background: #fff; color: var(--c-text);
}
.times { font-weight: 700; color: var(--c-muted); }

.matrix-label { margin-bottom: 14px; }
.var-a {
  color: var(--c-var); font-weight: 700;
  font-family: 'PT Serif', serif; font-style: italic; font-size: 17px;
}

.matrix-input {
  display: flex; flex-direction: column; gap: 12px;
  max-width: 760px; margin-bottom: 22px;
}
.matrix-input .mi-row { display: flex; gap: 14px; }
.matrix-input input {
  flex: 1; min-width: 64px;
  padding: 8px 12px; font-size: 15px;
  border: 1px solid #B8B8B8; border-radius: 3px; background: #fff; color: var(--c-text);
  outline: none;
}
.matrix-input input:focus {
  border-color: var(--c-primary);
  box-shadow: 0 0 0 2px var(--c-soft);
}

.reduced { display: inline-flex; align-items: center; gap: 9px; cursor: pointer; margin-bottom: 18px; }
.reduced input { width: 17px; height: 17px; accent-color: var(--c-primary); cursor: pointer; }

.hint { font-size: 14px; margin: 0 0 20px; max-width: 60em; }

/* ---------- buttons ---------- */
.actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.btn {
  cursor: pointer; font-family: inherit; font-weight: 700;
  font-size: 13px; letter-spacing: 0.04em;
  padding: 10px 22px; border-radius: 4px; color: #fff; border: 1px solid transparent;
}
.btn:hover { filter: brightness(1.06); }
.btn-primary { border-color: var(--c-primary-dark); background: linear-gradient(180deg, var(--c-primary-lite), var(--c-primary)); }
.btn-grey    { border-color: #555; background: linear-gradient(180deg, #7A8A7E, #5C6B60); }
.btn-ghost   { color: #333; background: #fff; border: 1px solid #B8B8B8; font-weight: 600; letter-spacing: 0; padding: 8px 16px; }
.btn-ghost:hover { border-color: var(--c-primary); filter: none; }

/* ---------- results ---------- */
.results { padding: 18px 30px 34px; }
.section-head {
  text-align: center;
  font-family: 'PT Serif', serif; font-weight: 700; font-size: 27px;
  color: var(--c-primary); margin: 30px 0 18px;
}
.section-head:first-child { margin-top: 14px; }

.center-line {
  display: flex; align-items: center; justify-content: center;
  gap: 12px; flex-wrap: wrap; font-size: 16px;
}
.center-line .lead { font-weight: 700; }

.step { padding: 10px 0; }
.step p { margin: 0 0 10px; font-size: 16px; }
.step .eq { font-family: 'PT Serif', serif; font-style: italic; }
.no-steps { text-align: center; color: var(--c-muted); margin: 14px 0; }

.export { margin-top: 26px; }

/* ---------- matrices ---------- */
.matrix {
  display: inline-flex; align-items: stretch;
  font-family: 'PT Serif', serif;
}
.matrix .br { width: 8px; align-self: stretch; border: 2px solid #333; }
.matrix .br-l { border-right: none; }
.matrix .br-r { border-left: none; }
.matrix .body { display: flex; flex-direction: column; gap: 4px; padding: 6px 14px; }
.matrix .m-row { display: flex; gap: 18px; }
.matrix .m-cell { min-width: 24px; text-align: center; font-size: 17px; }

.matrix.accent .br { border-color: var(--c-primary); }
.matrix.accent .body { color: var(--c-primary); font-weight: 700; }

.var-a.suffix { margin-left: 2px; }

/* ---------- article / SEO ---------- */
.article { margin-top: 30px; }
.article:first-of-type { margin-top: 38px; }
.article h2 { font-family: 'PT Serif', serif; font-weight: 700; font-size: 26px; margin: 0 0 14px; }
.article p { margin: 0 0 14px; }
.article p:last-child { margin-bottom: 0; }

.table-wrap { overflow-x: auto; border: 1px solid var(--c-border); border-radius: 3px; }
table { width: 100%; border-collapse: collapse; font-size: 15px; min-width: 520px; background: #fff; }
thead tr { background: #F0F1F2; }
th, td { text-align: left; padding: 12px 16px; }
th { font-weight: 700; }
tbody tr { border-top: 1px solid #E2E2E2; }
td:first-child { font-weight: 600; }
.accent { color: var(--c-primary); font-weight: 600; }

.app-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.app-card { background: #fff; border: 1px solid var(--c-border); border-radius: 3px; padding: 18px 20px; }
.app-card h3 { font-family: 'PT Serif', serif; font-weight: 700; font-size: 17px; margin: 0 0 6px; }
.app-card p { font-size: 14px; color: var(--c-muted); margin: 0; }

.faq-list { display: flex; flex-direction: column; gap: 10px; }
.faq { background: #fff; border: 1px solid var(--c-border); border-radius: 3px; padding: 16px 20px; }
.faq h3 { font-family: 'PT Serif', serif; font-weight: 700; font-size: 16px; margin: 0 0 6px; }
.faq p { font-size: 14.5px; color: var(--c-muted); margin: 0; }

/* ---------- footer ---------- */
.site-footer { background: var(--c-primary-dark); color: rgba(255,255,255,0.9); }
.site-footer .wrap {
  display: flex; align-items: center; justify-content: space-between;
  gap: 16px; flex-wrap: wrap; padding: 22px 20px; font-size: 13px;
}
.site-footer .brand-name { color: #fff; font-size: 15px; }

/* ---------- responsive ---------- */
@media (max-width: 720px) {
  .page-title { font-size: 25px; }
  .nav-main { gap: 16px; flex-wrap: wrap; }
  .nav-main, .brand { font-size: 12px; }
  .app-grid { grid-template-columns: 1fr; }
  .size-row input { width: 110px; }
  .calculator, .results, .box { padding-left: 18px; padding-right: 18px; }
  .matrix-input input { min-width: 48px; padding: 8px 6px; }
}

/* ---------- print ---------- */
@media print {
  .site-header, .site-footer, .actions, .breadcrumb, .calculator .size-row,
  .reduced, .hint { display: none !important; }
}