/*
 * Engineering Calculators - frontend styles
 * Design language: modern, minimal, confident. One bold move (the blue
 * result display); everything else quiet and disciplined. Built to the
 * frontend-design skill: deliberate type scale, purposeful structure,
 * accessible focus states, reduced-motion support, fully responsive.
 */

.engcalc-page {
	/* palette - blue is spent only on action + results */
	--ec-blue: #2563EB;
	--ec-blue-700: #1D4ED8;
	--ec-blue-050: #EFF4FF;
	--ec-ink: #0B1120;
	--ec-body: #334155;
	--ec-muted: #64748B;
	--ec-line: #E2E8F0;
	--ec-line-soft: #EEF2F7;
	--ec-surface: #FFFFFF;
	--ec-canvas: #F8FAFC;
	--ec-good: #059669;
	--ec-bad: #DC2626;

	--ec-r-lg: 20px;
	--ec-r-md: 12px;
	--ec-r-sm: 8px;
	--ec-maxw: 760px;

	font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
	color: var(--ec-body);
	line-height: 1.7;
	font-size: 17px;
	-webkit-font-smoothing: antialiased;
}
.engcalc-page *, .engcalc-page *::before, .engcalc-page *::after { box-sizing: border-box; }
.engcalc-container { max-width: var(--ec-maxw); margin: 0 auto; padding: 0 20px; }

/* ---------- Breadcrumb ---------- */
.engcalc-breadcrumb { font-size: 14px; padding: 22px 0 6px; }
.engcalc-breadcrumb ol { list-style: none; display: flex; flex-wrap: wrap; gap: 8px; margin: 0; padding: 0; }
.engcalc-breadcrumb li { display: flex; align-items: center; color: var(--ec-muted); }
.engcalc-breadcrumb li:not(:last-child)::after { content: '/'; margin-left: 8px; color: var(--ec-line); }
.engcalc-breadcrumb a { color: var(--ec-muted); text-decoration: none; transition: color .15s; }
.engcalc-breadcrumb a:hover { color: var(--ec-blue); }
.engcalc-breadcrumb li[aria-current] { color: var(--ec-ink); font-weight: 500; }

/* ---------- Header ---------- */
.engcalc-header { padding: 10px 0 4px; }
.engcalc-header h1 {
	font-size: clamp(2rem, 5vw, 2.85rem);
	line-height: 1.08;
	margin: 0 0 16px;
	font-weight: 800;
	letter-spacing: -0.032em;
	color: var(--ec-ink);
}
.engcalc-intro { font-size: 1.15rem; line-height: 1.6; color: var(--ec-body); margin: 0; max-width: 62ch; }

/* ---------- Calculator (the hero) ---------- */
.engcalc-tool {
	margin: 28px 0 40px;
	border: 1px solid var(--ec-line);
	border-radius: var(--ec-r-lg);
	background: var(--ec-surface);
	box-shadow: 0 1px 2px rgba(11,17,32,.04), 0 12px 32px -16px rgba(11,17,32,.16);
	overflow: hidden;
}
.engcalc-tool-grid { display: grid; grid-template-columns: 1fr 1fr; }
@media (max-width: 680px) { .engcalc-tool-grid { grid-template-columns: 1fr; } }

.engcalc-tool-inputs { padding: 26px; }
@media (max-width: 680px) { .engcalc-tool-inputs { padding: 20px; } }

.engcalc-form { display: flex; flex-direction: column; gap: 16px; }
.engcalc-field-row { display: flex; flex-direction: column; gap: 7px; }
.engcalc-field-row label { font-size: 14px; font-weight: 600; color: var(--ec-ink); }
.engcalc-input-wrap {
	display: flex; align-items: stretch;
	border: 1.5px solid var(--ec-line);
	border-radius: var(--ec-r-sm);
	background: var(--ec-canvas);
	overflow: hidden;
	transition: border-color .15s, box-shadow .15s, background .15s;
}
.engcalc-input-wrap:focus-within { border-color: var(--ec-blue); background: #fff; box-shadow: 0 0 0 4px rgba(37,99,235,.12); }
.engcalc-input-wrap input, .engcalc-input-wrap select {
	flex: 1; min-width: 0; border: 0; outline: 0; background: transparent;
	padding: 12px 14px; font-size: 16px; font-family: inherit; color: var(--ec-ink);
}
.engcalc-input-wrap select { cursor: pointer; appearance: none; -webkit-appearance: none;
	background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath fill='%2364748B' d='M6 8L0 2l1.4-1.4L6 5.2 10.6.6 12 2z'/%3E%3C/svg%3E");
	background-repeat: no-repeat; background-position: right 14px center; padding-right: 36px; }
.engcalc-input-wrap .engcalc-unit {
	display: flex; align-items: center; padding: 0 14px;
	background: var(--ec-line-soft); color: var(--ec-muted);
	font-size: 14px; font-weight: 600; border-left: 1px solid var(--ec-line); white-space: nowrap;
}
.engcalc-tool-note { font-size: 13px; color: var(--ec-muted); margin: 14px 0 0; line-height: 1.5; }

/* the one bold action */
.engcalc-calculate {
	width: 100%; margin-top: 20px;
	border: 0; border-radius: var(--ec-r-sm);
	background: var(--ec-blue); color: #fff;
	font-family: inherit; font-size: 16px; font-weight: 600; letter-spacing: -0.01em;
	padding: 14px 20px; cursor: pointer;
	transition: background .15s, transform .05s;
}
.engcalc-calculate:hover { background: var(--ec-blue-700); }
.engcalc-calculate:active { transform: translateY(1px); }
.engcalc-calculate:focus-visible { outline: 3px solid rgba(37,99,235,.4); outline-offset: 2px; }

/* results panel - the blue display */
.engcalc-results-panel {
	padding: 26px;
	background: linear-gradient(170deg, #1E3A8A 0%, #2563EB 100%);
	color: #fff;
	display: flex; flex-direction: column; gap: 14px;
}
@media (max-width: 680px) { .engcalc-results-panel { padding: 20px; } }
.engcalc-results-panel.is-empty { background: var(--ec-canvas); color: var(--ec-muted); }
.engcalc-results-panel.is-empty .engcalc-results-title { color: var(--ec-muted); }
.engcalc-results-title {
	font-size: 13px; font-weight: 700; margin: 0;
	letter-spacing: 0.04em; text-transform: uppercase; opacity: .8;
}
.engcalc-results-list { display: flex; flex-direction: column; gap: 8px; }
.engcalc-result-row {
	display: flex; justify-content: space-between; align-items: baseline; gap: 12px;
	padding: 12px 14px; border-radius: var(--ec-r-sm);
	background: rgba(255,255,255,.12);
}
.engcalc-result-row.is-primary { background: #fff; }
.engcalc-result-row.is-primary .engcalc-result-label { color: var(--ec-muted); }
.engcalc-result-row.is-primary .engcalc-result-value { color: var(--ec-ink); }
.engcalc-result-label { font-size: 14px; font-weight: 500; opacity: .95; }
.engcalc-result-value { font-size: 22px; font-weight: 700; font-variant-numeric: tabular-nums; letter-spacing: -0.02em; }
.engcalc-result-value em { font-size: 13px; font-weight: 500; font-style: normal; opacity: .7; margin-left: 3px; }
.engcalc-result-row.is-note { justify-content: center; background: transparent; border: 1px dashed rgba(255,255,255,.3); }
.engcalc-results-panel.is-empty .engcalc-result-row.is-note { border-color: var(--ec-line); }
.engcalc-result-note { font-size: 14px; text-align: center; opacity: .85; }
.engcalc-result-row.is-status-good .engcalc-result-value { color: #6EE7B7; }
.engcalc-result-row.is-status-bad .engcalc-result-value { color: #FCA5A5; }
.engcalc-result-row.is-primary.is-status-good .engcalc-result-value { color: var(--ec-good); }
.engcalc-result-row.is-primary.is-status-bad .engcalc-result-value { color: var(--ec-bad); }

/* stale hint when inputs change after calculating */
.engcalc-results-panel.is-stale .engcalc-results-list { opacity: .45; transition: opacity .2s; }
.engcalc-results-panel.is-stale::after {
	content: 'Values changed - press Calculate again';
	font-size: 12px; text-align: center; opacity: .85; margin-top: -4px;
}

/* inline chart */
.engcalc-chart { display: flex; flex-direction: column; gap: 9px; padding-top: 4px; }
.engcalc-chart-title { font-size: 12px; font-weight: 700; letter-spacing: 0.04em; text-transform: uppercase; opacity: .8; margin: 4px 0 2px; }
.engcalc-chart-row { display: grid; grid-template-columns: 1fr 2fr auto; align-items: center; gap: 10px; font-size: 13px; }
.engcalc-chart-label { opacity: .9; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.engcalc-chart-track { height: 8px; border-radius: 99px; background: rgba(255,255,255,.18); overflow: hidden; }
.engcalc-chart-bar { display: block; height: 100%; border-radius: 99px; background: rgba(255,255,255,.55); transition: width .4s cubic-bezier(.4,0,.2,1); }
.engcalc-chart-bar.is-primary { background: #fff; }
.engcalc-chart-val { font-variant-numeric: tabular-nums; font-weight: 600; white-space: nowrap; }

/* ---------- Content sections ---------- */
.engcalc-section { margin: 34px 0; }
.engcalc-section h2 {
	font-size: 1.6rem; font-weight: 750; margin: 0 0 14px;
	letter-spacing: -0.022em; color: var(--ec-ink); line-height: 1.2;
	font-weight: 700;
}
.engcalc-section h3 { font-size: 1.2rem; font-weight: 650; margin: 22px 0 8px; color: var(--ec-ink); font-weight: 600; }
.engcalc-section p { margin: 0 0 15px; }
.engcalc-section a { color: var(--ec-blue-700); text-decoration: none; border-bottom: 1px solid rgba(37,99,235,.3); transition: border-color .15s; }
.engcalc-section a:hover { border-bottom-color: var(--ec-blue-700); }
.engcalc-section ul, .engcalc-section ol { margin: 0 0 15px; padding-left: 22px; }
.engcalc-section li { margin-bottom: 8px; }
.engcalc-section strong { color: var(--ec-ink); font-weight: 650; font-weight: 600; }

/* formula block - distinct, technical, monospace numerals */
.engcalc-formula {
	background: var(--ec-ink); color: #E2E8F0;
	border-radius: var(--ec-r-md); padding: 16px 20px; margin: 16px 0;
	font-size: 1.08rem; font-weight: 500; overflow-x: auto;
	font-variant-numeric: tabular-nums;
	box-shadow: inset 0 0 0 1px rgba(255,255,255,.04);
}
.engcalc-formula sub { font-size: .7em; }

/* tables */
.engcalc-section table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 15px; }
.engcalc-section th, .engcalc-section td { border: 1px solid var(--ec-line); padding: 11px 14px; text-align: left; }
.engcalc-section th { background: var(--ec-canvas); font-weight: 600; color: var(--ec-ink); }
.engcalc-section tbody tr:nth-child(even) { background: #FBFCFE; }

/* ---------- FAQ ---------- */
.engcalc-faq details {
	border: 1px solid var(--ec-line); border-radius: var(--ec-r-md);
	margin-bottom: 10px; background: var(--ec-surface); overflow: hidden;
}
.engcalc-faq details[open] { border-color: #CBD8EE; }
.engcalc-faq summary {
	padding: 16px 18px; font-weight: 600; color: var(--ec-ink); cursor: pointer;
	list-style: none; display: flex; justify-content: space-between; align-items: center; gap: 12px;
}
.engcalc-faq summary::-webkit-details-marker { display: none; }
.engcalc-faq summary::after {
	content: ''; width: 10px; height: 10px; flex-shrink: 0;
	border-right: 2px solid var(--ec-blue); border-bottom: 2px solid var(--ec-blue);
	transform: rotate(45deg); transition: transform .2s; margin-top: -4px;
}
.engcalc-faq details[open] summary::after { transform: rotate(-135deg); margin-top: 2px; }
.engcalc-faq summary:hover { background: var(--ec-canvas); }
.engcalc-faq .engcalc-faq-body { padding: 0 18px 18px; color: var(--ec-body); }
.engcalc-faq .engcalc-faq-body p { margin: 0; }

/* ---------- Related calculators ---------- */
.engcalc-related-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 12px; }
.engcalc-related-card {
	display: block; padding: 16px 18px; border: 1px solid var(--ec-line);
	border-radius: var(--ec-r-md); background: var(--ec-surface); text-decoration: none;
	transition: border-color .15s, box-shadow .15s, transform .15s;
}
.engcalc-related-card:hover { border-color: var(--ec-blue); box-shadow: 0 8px 24px -14px rgba(37,99,235,.5); transform: translateY(-2px); }
.engcalc-related-card .ec-rc-cat { display: block; font-size: 12px; color: var(--ec-blue); font-weight: 600; margin-bottom: 4px; }
.engcalc-related-card .ec-rc-title { display: block; font-size: 15px; font-weight: 600; color: var(--ec-ink); line-height: 1.35; }

/* ---------- Related articles ---------- */
.engcalc-articles-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 16px; }
.engcalc-article-card {
	display: flex; flex-direction: column; border: 1px solid var(--ec-line);
	border-radius: var(--ec-r-md); overflow: hidden; background: var(--ec-surface);
	text-decoration: none; transition: border-color .15s, box-shadow .15s, transform .15s;
}
.engcalc-article-card:hover { border-color: var(--ec-blue); box-shadow: 0 8px 24px -14px rgba(37,99,235,.5); transform: translateY(-2px); }
.engcalc-article-thumb { display: block; width: 100%; aspect-ratio: 16/9; background-size: cover; background-position: center; background-color: var(--ec-line-soft); }
.engcalc-article-body { padding: 14px 16px; display: flex; flex-direction: column; gap: 6px; }
.engcalc-article-title { font-size: 15px; font-weight: 600; color: var(--ec-ink); line-height: 1.35; }
.engcalc-article-excerpt { font-size: 13px; color: var(--ec-muted); line-height: 1.5; }

/* ---------- Category page ---------- */
.engcalc-cat-header { padding: 22px 0 4px; }
.engcalc-cat-header h1 { font-size: clamp(2rem, 5vw, 2.7rem); margin: 0 0 14px; font-weight: 800; letter-spacing: -0.03em; color: var(--ec-ink); }
.engcalc-cat-desc { color: var(--ec-body); font-size: 1.15rem; max-width: 62ch; margin: 0; }
.engcalc-tools-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; margin: 26px 0 44px; }

/* ---------- Accessibility ---------- */
.engcalc-calculate:focus-visible, .engcalc-faq summary:focus-visible, .engcalc-related-card:focus-visible, .engcalc-article-card:focus-visible {
	outline: 3px solid rgba(37,99,235,.45); outline-offset: 2px;
}
@media (prefers-reduced-motion: reduce) {
	.engcalc-page *, .engcalc-page *::before, .engcalc-page *::after { transition: none !important; animation: none !important; }
}

/* result share / copy actions */
.engcalc-actions { display: flex; gap: 8px; margin-top: 14px; padding-top: 14px; border-top: 1px solid rgba(255,255,255,.2); }
.engcalc-results-panel.is-empty .engcalc-actions { border-top-color: var(--ec-line); }
.engcalc-action {
	display: inline-flex; align-items: center; gap: 7px; cursor: pointer;
	background: rgba(255,255,255,.15); color: #fff; border: 1px solid rgba(255,255,255,.25);
	border-radius: 8px; padding: 8px 14px; font: inherit; font-size: 13.5px; font-weight: 600;
	transition: background .15s, border-color .15s;
}
.engcalc-action:hover { background: rgba(255,255,255,.28); border-color: rgba(255,255,255,.5); }
.engcalc-action svg { flex-shrink: 0; }

/* home link card accent */
.engcalc-related-card.is-home .ec-rc-cat { color: var(--ec-accent, #7C3AED); }
.engcalc-related-card.is-category .ec-rc-cat { color: var(--ec-good, #059669); }

/* category intro link paragraph, right under the calculator */
.engcalc-cat-intro { margin: 18px 0 6px; font-size: 15.5px; color: var(--ec-body, #3B475C); }
.engcalc-cat-intro a { color: var(--ec-blue-700, #1D4ED8); border-bottom: 1px solid rgba(37,99,235,.3); text-decoration: none; }
.engcalc-cat-intro a:hover { border-bottom-color: var(--ec-blue-700, #1D4ED8); }

/* parent hub page: grouped child categories */
.engcalc-parent-group { margin: 32px 0; }
.engcalc-parent-group > h2 { font-size: 20px; margin: 0 0 14px; padding-bottom: 8px; border-bottom: 2px solid var(--ec-line, #E8ECF2); }
.engcalc-parent-group > h2 a { color: var(--ec-ink, #0F172A); text-decoration: none; }
.engcalc-parent-group > h2 a:hover { color: var(--ec-blue-700, #1D4ED8); }