/* Matrix Analysis -- web edition.
   Palette carries over the green icon and the amber result panel of the
   original Flash app. Mobile first, because the app it replaces was an iPhone
   app; wider screens just get more breathing room. */

:root {
	--green-900: #063d09;
	--green-700: #0c5a10;
	--green-600: #147a19;
	--green-100: #d8f5d9;
	/* Accent for text and icons sitting on a soft background. The solid greens
	   above stay as they are in dark mode because they are also fill colours. */
	--accent-text: #0c5a10;
	--amber: #ffd860;
	--amber-deep: #7a5600;

	--bg: #f2f4f0;
	--surface: #ffffff;
	--surface-2: #f7f9f6;
	--ink: #16211a;
	--ink-soft: #5c6b60;
	--line: #d7ded8;
	--cell: #eef2ff;
	--cell-line: #c3cbe8;
	--danger: #b3261e;
	--danger-bg: #fbeae9;

	--radius: 14px;
	--gap: 12px;
}

@media (prefers-color-scheme: dark) {
	:root {
		--bg: #10140f;
		--surface: #1a201a;
		--surface-2: #212822;
		--ink: #e8efe7;
		--ink-soft: #9dab9f;
		--line: #333c34;
		--cell: #1e2436;
		--cell-line: #3b456a;
		--green-100: #123d15;
		--accent-text: #86d98d;
		--danger: #ff8a80;
		--danger-bg: #2c1a19;
	}
}

* { box-sizing: border-box; }

/* Any author rule setting `display` outranks the user agent's [hidden] rule,
   which silently un-hides elements. Settle it once for the whole sheet. */
[hidden] { display: none !important; }

html, body {
	margin: 0;
	padding: 0;
}

body {
	background: var(--bg);
	color: var(--ink);
	font: 16px/1.45 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
	-webkit-text-size-adjust: 100%;
	padding-bottom: env(safe-area-inset-bottom);
}

/* ---------- header ---------- */

.topbar {
	display: flex;
	align-items: center;
	gap: 14px;
	padding: calc(14px + env(safe-area-inset-top)) 16px 14px;
	background: var(--green-700);
	color: #fff;
}

.topbar-text h1 {
	margin: 0;
	font-size: 1.3rem;
	letter-spacing: 0.2px;
}

.topbar-text p {
	margin: 2px 0 0;
	font-size: 0.8rem;
	opacity: 0.82;
}

.logo {
	display: grid;
	grid-template-columns: repeat(3, 1fr);
	gap: 3px;
	width: 38px;
	height: 38px;
	flex: none;
}

.logo span {
	border: 2.5px solid #fff;
	border-radius: 1px;
	background: rgba(255, 255, 255, 0.28);
}

/* ---------- layout ---------- */

main {
	max-width: 860px;
	margin: 0 auto;
	padding: 16px 14px 28px;
	display: flex;
	flex-direction: column;
	gap: var(--gap);
}

.panel {
	background: var(--surface);
	border: 1px solid var(--line);
	border-radius: var(--radius);
	padding: 14px;
}

.panel-title {
	margin: 0 0 10px;
	font-size: 0.75rem;
	font-weight: 700;
	letter-spacing: 0.09em;
	text-transform: uppercase;
	color: var(--ink-soft);
}

.hint {
	margin: 10px 0 0;
	font-size: 0.78rem;
	color: var(--ink-soft);
}

.hint code {
	background: var(--surface-2);
	border: 1px solid var(--line);
	border-radius: 4px;
	padding: 0 4px;
}

/* ---------- size steppers ---------- */

.size-row {
	display: flex;
	align-items: flex-end;
	gap: 10px;
}

.stepper { flex: 1 1 0; min-width: 0; }

.stepper label {
	display: block;
	font-size: 0.75rem;
	color: var(--ink-soft);
	margin-bottom: 6px;
}

.stepper-controls {
	display: flex;
	align-items: stretch;
	border: 1px solid var(--line);
	border-radius: 10px;
	overflow: hidden;
	background: var(--surface-2);
}

.stepper-controls input {
	flex: 1 1 auto;
	min-width: 0;
	border: 0;
	background: transparent;
	color: var(--ink);
	font-size: 1.05rem;
	font-weight: 700;
	text-align: center;
	padding: 10px 0;
	-moz-appearance: textfield;
	appearance: textfield;
}

.stepper-controls input::-webkit-outer-spin-button,
.stepper-controls input::-webkit-inner-spin-button {
	-webkit-appearance: none;
	margin: 0;
}

.step {
	flex: none;
	width: 42px;
	border: 0;
	background: transparent;
	color: var(--accent-text);
	font-size: 1.3rem;
	font-weight: 700;
	cursor: pointer;
}

.step:active { background: var(--green-100); }

.times {
	padding-bottom: 12px;
	color: var(--ink-soft);
	font-size: 1.1rem;
}

/* ---------- chips ---------- */

.preset-row, .bulk-actions {
	display: flex;
	flex-wrap: wrap;
	gap: 8px;
	margin-top: 12px;
	align-items: center;
}

.chip {
	border: 1px solid var(--line);
	background: var(--surface-2);
	color: var(--ink);
	border-radius: 999px;
	padding: 8px 14px;
	font-size: 0.85rem;
	font-weight: 600;
	cursor: pointer;
}

.chip:hover { border-color: var(--accent-text); color: var(--accent-text); }

.chip[aria-expanded="true"] {
	background: var(--green-100);
	border-color: var(--accent-text);
	color: var(--accent-text);
}

/* ---------- second operand ---------- */

.mode-row {
	display: flex;
	flex-wrap: wrap;
	gap: 8px;
}

.mode {
	flex: 1 1 auto;
	border: 1px solid var(--line);
	background: var(--surface-2);
	color: var(--ink-soft);
	border-radius: 10px;
	padding: 10px 12px;
	font-size: 0.85rem;
	font-weight: 600;
	cursor: pointer;
	white-space: nowrap;
}

.mode.is-active {
	background: var(--green-100);
	border-color: var(--accent-text);
	color: var(--accent-text);
}

#operand-body { margin-top: 12px; }

#operand-body .size-row { margin-bottom: 12px; }

/* ---------- solution vectors ---------- */

.vec-row {
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	gap: 10px;
	overflow-x: auto;
	-webkit-overflow-scrolling: touch;
}

.vec {
	display: flex;
	align-items: center;
	gap: 6px;
}

.vec-label {
	font: 700 0.95rem/1 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	color: var(--ink-soft);
	white-space: nowrap;
}

/* ---------- named solution list ---------- */

.sol-list {
	display: grid;
	grid-template-columns: auto 1fr;
	gap: 6px 12px;
	align-items: center;
	margin: 0;
	max-width: 320px;
}

.sol-list dt {
	font: 700 1rem/1.2 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	color: var(--ink-soft);
	text-align: right;
}

.sol-list dd {
	margin: 0;
	background: var(--cell);
	border: 1px solid var(--cell-line);
	border-radius: 8px;
	padding: 8px 12px;
	font: 700 1rem/1.2 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	overflow-wrap: anywhere;
}

/* ---------- eigenvalues ---------- */

.eigen-block {
	border-top: 1px solid var(--line);
	padding-top: 12px;
	margin-top: 12px;
}

.eigen-block:first-of-type {
	border-top: 0;
	padding-top: 0;
}

.eigen-head {
	display: flex;
	flex-wrap: wrap;
	align-items: baseline;
	gap: 4px 12px;
	margin: 0 0 10px;
}

.eigen-value {
	font: 700 1.15rem/1.2 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	overflow-wrap: anywhere;
}

.eigen-meta {
	font-size: 0.76rem;
	letter-spacing: 0.03em;
	text-transform: uppercase;
	color: var(--ink-soft);
}

/* ---------- bulk paste ---------- */

.bulk textarea {
	width: 100%;
	border: 1px solid var(--line);
	border-radius: 10px;
	background: var(--surface-2);
	color: var(--ink);
	padding: 10px;
	font: 0.9rem/1.5 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	resize: vertical;
}

.bulk-msg {
	font-size: 0.8rem;
	color: var(--accent-text);
}

/* ---------- input grid ---------- */

.grid-scroll {
	overflow-x: auto;
	-webkit-overflow-scrolling: touch;
	margin: 0 -4px;
	padding: 0 4px 4px;
}

.grid {
	display: grid;
	gap: 6px;
	min-width: min-content;
}

.grid input {
	width: 100%;
	min-width: 58px;
	padding: 10px 4px;
	border: 1px solid var(--cell-line);
	border-radius: 8px;
	background: var(--cell);
	color: var(--ink);
	font-size: 1rem;
	font-weight: 600;
	text-align: center;
}

.grid input:focus {
	outline: 2px solid var(--accent-text);
	outline-offset: 1px;
}

.grid input.bad {
	border-color: var(--danger);
	box-shadow: inset 0 0 0 1px var(--danger);
}

/* ---------- analyze bar ---------- */

.analyze-bar {
	display: flex;
	gap: 10px;
	align-items: stretch;
}

.primary {
	flex: 1 1 auto;
	border: 0;
	border-radius: 12px;
	background: linear-gradient(180deg, var(--green-600), var(--green-700));
	color: #fff;
	font-size: 1.05rem;
	font-weight: 700;
	letter-spacing: 0.02em;
	padding: 14px 18px;
	cursor: pointer;
	box-shadow: 0 2px 0 var(--green-900);
}

.primary:active {
	transform: translateY(1px);
	box-shadow: 0 1px 0 var(--green-900);
}

.format-toggle {
	display: flex;
	flex: none;
	border: 1px solid var(--line);
	border-radius: 12px;
	overflow: hidden;
	background: var(--surface);
}

.fmt {
	border: 0;
	background: transparent;
	color: var(--ink-soft);
	font-size: 0.82rem;
	font-weight: 600;
	padding: 0 14px;
	cursor: pointer;
}

.fmt.is-active {
	background: var(--green-100);
	color: var(--accent-text);
}

.error {
	margin: 0;
	padding: 12px 14px;
	border: 1px solid var(--danger);
	border-radius: var(--radius);
	background: var(--danger-bg);
	color: var(--danger);
	font-size: 0.9rem;
	font-weight: 600;
}

/* ---------- results ---------- */

#results {
	display: flex;
	flex-direction: column;
	gap: var(--gap);
}

.facts {
	display: grid;
	grid-template-columns: repeat(auto-fit, minmax(112px, 1fr));
	gap: 10px;
	margin: 0;
}

.facts div {
	background: var(--surface-2);
	border: 1px solid var(--line);
	border-radius: 10px;
	padding: 9px 10px;
	min-width: 0;
}

.facts dt {
	font-size: 0.68rem;
	letter-spacing: 0.07em;
	text-transform: uppercase;
	color: var(--ink-soft);
}

.facts dd {
	margin: 3px 0 0;
	font-size: 1.05rem;
	font-weight: 700;
	overflow-wrap: anywhere;
}

.tags {
	display: flex;
	flex-wrap: wrap;
	gap: 6px;
	list-style: none;
	margin: 12px 0 0;
	padding: 0;
}

.tags li {
	font-size: 0.74rem;
	font-weight: 700;
	letter-spacing: 0.03em;
	padding: 4px 10px;
	border-radius: 999px;
	background: var(--green-100);
	color: var(--accent-text);
}

.tags li.warn {
	background: #ffeeb8;
	color: var(--amber-deep);
}

.det-card {
	background: linear-gradient(180deg, var(--amber), #f2c437);
	border-color: #d8ae2b;
	color: #2a1f00;
}

.det-card .panel-title { color: #6a4e00; }

.det-value {
	margin: 0;
	font: 700 2rem/1.15 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	overflow-wrap: anywhere;
}

.det-note {
	margin: 8px 0 0;
	font-size: 0.82rem;
	color: #5b4300;
}

/* ---------- tabs ---------- */

.tabs {
	display: flex;
	gap: 6px;
	overflow-x: auto;
	-webkit-overflow-scrolling: touch;
	padding-bottom: 10px;
	margin-bottom: 4px;
	border-bottom: 1px solid var(--line);
}

.tab {
	flex: none;
	border: 1px solid var(--line);
	background: var(--surface-2);
	color: var(--ink-soft);
	border-radius: 999px;
	padding: 7px 14px;
	font-size: 0.82rem;
	font-weight: 600;
	cursor: pointer;
	white-space: nowrap;
}

.tab[aria-selected="true"] {
	background: var(--green-700);
	border-color: var(--green-700);
	color: #fff;
}

.tab-body { padding-top: 12px; }

.tab-note {
	margin: 0 0 10px;
	font-size: 0.82rem;
	color: var(--ink-soft);
}

.matrix-out {
	overflow-x: auto;
	-webkit-overflow-scrolling: touch;
	padding-bottom: 4px;
}

.matrix-out table {
	border-collapse: separate;
	border-spacing: 6px;
	margin: 0 auto;
}

.matrix-out td {
	background: var(--cell);
	border: 1px solid var(--cell-line);
	border-radius: 8px;
	padding: 9px 12px;
	text-align: center;
	font: 600 0.95rem/1.2 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	white-space: nowrap;
}

.matrix-out td.pivot {
	background: var(--green-100);
	border-color: var(--accent-text);
	color: var(--accent-text);
}

.empty-note {
	margin: 0;
	font-size: 0.88rem;
	color: var(--ink-soft);
}

/* ---------- footer ---------- */

footer {
	max-width: 860px;
	margin: 0 auto;
	padding: 4px 16px 28px;
	color: var(--ink-soft);
	font-size: 0.76rem;
	text-align: center;
}

footer p { margin: 2px 0; }
footer a { color: var(--accent-text); }

@media (min-width: 620px) {
	.topbar { padding-left: 24px; padding-right: 24px; }
	main { padding: 20px 20px 32px; }
	.det-value { font-size: 2.4rem; }
}