:root {
	--tertiary: #943700;
	--surface-variant: #e0e3e5;
	--surface-container-low: #f2f4f6;
	--on-surface: #191c1e;
	--primary: #004ac6;
	--inverse-on-surface: #eff1f3;
	--surface-container-lowest: #ffffff;
	--surface-container: #eceef0;
	--on-primary: #ffffff;
	--surface: #f7f9fb;
	--inverse-surface: #2d3133;
	--secondary-container: #d0e1fb;
	--on-surface-variant: #434655;
	--outline-variant: #c3c6d7;
	--outline: #737686;
	--on-secondary-container: #54647a;
	--surface-bright: #f7f9fb;
	--primary-container: #2563eb;

	--font-headline: "Manrope", sans-serif;
	--font-body: "Inter", sans-serif;

	--radius-md: 0.375rem;
	--radius-xl: 0.75rem;
	--radius-2xl: 1rem;

	--space-1: 0.25rem;
	--space-2: 0.5rem;
	--space-3: 0.75rem;
	--space-4: 1rem;
	--space-5: 1.25rem;
	--space-6: 1.5rem;
	--space-8: 2rem;
}

* {
	box-sizing: border-box;
}

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

/* Page base */
body {
	font-family: var(--font-body);
	background: var(--surface);
	color: var(--on-surface);
}

.hidden {
	/* Utility to toggle visibility from JS. */
	display: none !important;
}

.text-center {
	text-align: center;
}

/* Top bar */
.topbar {
	position: fixed;
	top: 0;
	left: 0;
	right: 0;
	z-index: 50;
	height: 4rem;
	padding: 0 var(--space-8);
	background: rgba(247, 249, 251, 0.88);
	backdrop-filter: blur(12px);
	display: flex;
	align-items: center;
	justify-content: flex-start;
	gap: var(--space-6);
	box-shadow: 0 8px 20px rgba(25, 28, 30, 0.04);
}

.topbar-brand {
	display: flex;
	flex-direction: column;
}

.brand-title {
	font-family: var(--font-headline);
	font-size: 1.25rem;
	font-weight: 700;
	line-height: 1.2;
	letter-spacing: -0.02em;
}

.brand-subtitle {
	margin-top: -0.1rem;
	font-size: 0.625rem;
	font-weight: 700;
	text-transform: uppercase;
	letter-spacing: 0.15em;
	color: var(--primary);
}

.app-main {
	padding: 6rem 1.5rem 0rem;
}

/* App layout */
.app-shell {
	max-width: 1500px;
	margin: 0 auto;
	display: grid;
	grid-template-columns: 1fr;
	gap: var(--space-6);
	align-items: start;
}

.panel {
	background: var(--surface-container-lowest);
	border-radius: var(--radius-2xl);
}

/* Config panel */
.config-panel {
	background: var(--surface-container-low);
	display: flex;
	flex-direction: column;
	overflow: hidden;
}

.panel-header {
	padding: var(--space-5);
	display: flex;
	align-items: center;
	gap: var(--space-2);
}

.panel-title {
	margin: 0;
	font-family: var(--font-headline);
	font-size: 0.95rem;
	font-weight: 700;
	letter-spacing: 0.05em;
	text-transform: uppercase;
	color: var(--on-surface);
}

.config-section {
	margin: 0 var(--space-4) var(--space-4);
	padding: var(--space-6);
	border-radius: var(--radius-xl);
	background: var(--surface-container-lowest);
}

.section-heading {
	display: flex;
	align-items: center;
	gap: var(--space-3);
	margin-bottom: var(--space-4);
}

.section-heading-between {
	justify-content: space-between;
}

.section-heading-left {
	display: flex;
	align-items: center;
	gap: var(--space-3);
}

.step-badge {
	width: 1.5rem;
	height: 1.5rem;
	border-radius: 999px;
	display: inline-flex;
	align-items: center;
	justify-content: center;
	font-size: 0.625rem;
	font-weight: 700;
	background: var(--primary);
	color: var(--on-primary);
}

.section-label {
	font-size: 0.6875rem;
	font-weight: 700;
	text-transform: uppercase;
	letter-spacing: 0.14em;
	color: var(--on-surface-variant);
}

.input-label {
	display: block;
	margin-bottom: var(--space-2);
	font-size: 0.6875rem;
	font-weight: 700;
	text-transform: uppercase;
	letter-spacing: 0.08em;
	color: var(--on-surface-variant);
}

/* Form controls */
.algo-select,
.input-field,
.process-input {
	width: 100%;
	background: var(--surface-container-low);
	border: 0;
	border-radius: var(--radius-md);
	padding: 0.6rem 0.75rem;
	font-size: 0.875rem;
	font-weight: 600;
	color: var(--on-surface);
	outline: 0;
	transition: background-color 0.2s ease, box-shadow 0.2s ease;
}

.algo-select {
	font-weight: 500;
	margin-bottom: var(--space-2);
}

.option-group {
	margin-top: var(--space-4);
	padding: var(--space-3);
	border-radius: var(--radius-xl);
	border: 1px solid var(--outline-variant);
	background: var(--surface-container-lowest);
	display: grid;
	gap: var(--space-2);
}

.radio-row {
	display: flex;
	align-items: center;
	gap: 0.5rem;
	font-size: 0.75rem;
	color: var(--on-surface-variant);
	padding: 0.45rem 0.6rem;
	border-radius: var(--radius-md);
	background: var(--surface-container-low);
}

.quantum-group {
	margin-top: var(--space-4);
}

/* Focus ring */
.algo-select:focus,
.input-field:focus,
.process-input:focus,
.counter-btn:focus-visible,
	.btn:focus-visible {
	/* Centralized focus style for accessible keyboard navigation. */
	box-shadow: 0 0 0 2px rgba(0, 74, 198, 0.35);
	outline: none;
}

.counter-control {
	display: inline-flex;
	align-items: center;
	border-radius: var(--radius-md);
	overflow: hidden;
	background: var(--surface-container-low);
}

.counter-btn {
	border: 0;
	background: transparent;
	color: var(--on-surface-variant);
	padding: 0.25rem 0.6rem;
	cursor: pointer;
	transition: background-color 0.2s ease;
}

.counter-btn:hover {
	background: var(--surface-container-lowest);
}

.counter-value {
	min-width: 2.25rem;
	text-align: center;
	font-size: 0.6875rem;
	font-weight: 700;
	color: var(--on-surface);
}

.process-table-wrap,
.results-table-wrap {
	overflow-x: auto;
}

.process-table,
.results-table {
	width: 100%;
	border-collapse: collapse;
}

.process-table th,
.results-table th {
	padding: 0.5rem 0.75rem;
	text-align: center;
	font-size: 0.625rem;
	font-weight: 700;
	letter-spacing: 0.05em;
	text-transform: uppercase;
	color: var(--on-surface-variant);
}

.process-row:hover,
.results-table tbody tr:hover {
	background: var(--surface-bright);
}

.process-cell {
	padding: 0.75rem 0.5rem;
	text-align: center;
}

/* PID chip */
.pid-pill {
	width: 1.6rem;
	height: 1.6rem;
	display: inline-flex;
	align-items: center;
	justify-content: center;
	border-radius: 0.375rem;
	font-size: 0.625rem;
	font-weight: 700;
	color: #ffffff;
	background: var(--pid-color, var(--surface-variant));
}

.process-input {
	width: 3.8rem;
	margin: 0 auto;
	display: block;
	text-align: center;
	font-size: 0.8125rem;
	padding: 0.45rem 0.55rem;
}

.process-input.is-invalid,
.input-field.is-invalid {
	box-shadow: 0 0 0 2px rgba(186, 26, 26, 0.45);
}

.panel-actions {
	margin-top: auto;
	padding: var(--space-6);
	display: grid;
	gap: var(--space-3);
}

.btn {
	border: 0;
	border-radius: var(--radius-md);
	font-family: var(--font-body);
	font-weight: 700;
	cursor: pointer;
	display: inline-flex;
	align-items: center;
	justify-content: center;
	gap: var(--space-2);
	transition: transform 0.2s ease, filter 0.2s ease;
}

.btn:hover {
	filter: brightness(1.03);
}

.btn:active {
	transform: scale(0.98);
}

.btn-primary {
	color: var(--on-primary);
	background: linear-gradient(135deg, var(--primary), var(--primary-container));
	padding: 0.75rem 1.25rem;
	font-size: 0.875rem;
}

.btn-secondary {
	color: var(--on-secondary-container);
	background: var(--secondary-container);
	padding: 0.7rem 1rem;
	font-size: 0.75rem;
}

.btn-full {
	width: 100%;
}

/* Snackbar */
.snackbar {
	/* Live region anchored to the viewport for validation feedback. */
	position: fixed;
	left: 50%;
	bottom: 1.25rem;
	transform: translate(-50%, 18px);
	min-width: 220px;
	max-width: min(90vw, 420px);
	padding: 0.7rem 0.9rem;
	border-radius: 0.7rem;
	background: var(--inverse-surface);
	color: var(--inverse-on-surface);
	font-size: 0.75rem;
	font-weight: 600;
	opacity: 0;
	pointer-events: none;
	transition: opacity 0.22s ease, transform 0.22s ease;
	z-index: 120;
}

.snackbar.show {
	opacity: 1;
	transform: translate(-50%, 0);
}

.snackbar.snackbar-error {
	background: #472527;
	color: #ffdad6;
}

.snackbar.snackbar-info {
	background: #1f3a72;
	color: #dbe1ff;
}

.content-column {
	display: grid;
	gap: var(--space-6);
}

.simulation-empty {
	min-height: 220px;
	display: flex;
	flex-direction: column;
	align-items: center;
	justify-content: center;
	text-align: center;
	padding: var(--space-8);
}

.simulation-title {
	margin: 0;
	font-family: var(--font-headline);
	font-size: 1.125rem;
	font-weight: 700;
}

.simulation-text {
	margin: var(--space-2) auto 0;
	max-width: 34rem;
	font-size: 0.875rem;
	line-height: 1.6;
	color: var(--on-surface-variant);
}

/* Gantt panel */
.gantt-panel {
	overflow: hidden;
}

.gantt-panel-header {
	justify-content: space-between;
}

.gantt-header-left {
	display: flex;
	align-items: center;
	gap: var(--space-2);
}

.gantt-replay-btn {
	padding: 0.35rem 0.75rem;
	font-size: 0.6875rem;
	flex-shrink: 0;
}

.icon-small {
	width: 1rem;
	height: 1rem;
	stroke-width: 2;
}

.gantt-body {
	padding: 0 var(--space-5) var(--space-5);
}

.gantt-canvas-wrap {
	/* Allow horizontal scrolling for wide schedules. */
	background: var(--surface-container-low);
	border-radius: var(--radius-xl);
	padding: var(--space-4) var(--space-4) var(--space-3);
	overflow-x: auto;
}

/* Gantt track */
.gantt {
	display: flex;
	height: 48px;
	border-radius: var(--radius-xl);
	overflow: hidden;
	background: var(--surface-container);
}

/* Gantt segment */
.block {
	/* Each block represents a scheduled slice in the timeline. */
	display: flex;
	align-items: center;
	justify-content: center;
	font-weight: 700;
	font-size: 0.75rem;
	color: #ffffff;
	white-space: nowrap;
	background: var(--pid-color, var(--outline-variant));
	transition: transform 0.2s ease;
}

.block:hover {
	transform: scale(1.02);
	z-index: 2;
}

.gantt-time {
	position: relative;
	height: 18px;
	font-size: 0.6875rem;
	color: var(--on-surface-variant);
}

.gantt-legend {
	display: flex;
	flex-wrap: wrap;
	gap: 0.5rem;
	margin-top: var(--space-4);
}

/* Legend item */
.legend-item {
	display: flex;
	align-items: center;
	gap: 0.375rem;
	font-size: 0.6875rem;
	font-weight: 600;
	color: var(--on-surface-variant);
	background: var(--surface-container-low);
	padding: 0.25rem 0.625rem;
	border-radius: 999px;
}

.legend-dot {
	width: 9px;
	height: 9px;
	border-radius: 50%;
	flex-shrink: 0;
	background: var(--pid-color, var(--outline-variant));
}

.metrics-grid {
	display: grid;
	grid-template-columns: 1fr;
	gap: var(--space-4);
}

/* Metric card */
.metric-card {
	padding: var(--space-6);
}

.metric-card-primary {
	box-shadow: inset 4px 0 0 var(--primary);
}

.metric-card-tertiary {
	box-shadow: inset 4px 0 0 var(--tertiary);
}

.metric-label {
	margin: 0 0 var(--space-1);
	font-size: 0.625rem;
	font-weight: 700;
	text-transform: uppercase;
	letter-spacing: 0.14em;
	color: var(--on-surface-variant);
}

.metric-value {
	margin: 0;
	font-family: var(--font-headline);
	font-size: 2.25rem;
	font-weight: 800;
	line-height: 1;
}

.metric-value-primary {
	color: var(--primary);
}

.metric-value-tertiary {
	color: var(--tertiary);
}

.metric-unit {
	font-family: var(--font-body);
	font-size: 0.875rem;
	font-weight: 400;
	color: var(--on-surface-variant);
}

.results-panel {
	overflow: hidden;
}

.results-table thead {
	background: rgba(242, 244, 246, 0.7);
}

.results-table td {
	padding: 0.9rem 1rem;
	font-size: 0.875rem;
	color: var(--on-surface-variant);
}

.results-table td:first-child {
	color: var(--on-surface);
	font-weight: 700;
}

.site-footer {
	padding: 1.5rem 0.75rem;
	text-align: center;
}

.footer-text {
	margin: 0;
	font-size: 0.8125rem;
	color: var(--on-surface-variant);
}

.footer-link {
	color: var(--primary);
	font-weight: 700;
	text-decoration: none;
}

.footer-link:hover {
	text-decoration: underline;
}

/* PID badge */
.pid-colored-pill {
	display: inline-flex;
	align-items: center;
	gap: 0.375rem;
	font-weight: 700;
	font-size: 0.875rem;
	color: var(--on-surface);
}

.pid-color-dot {
	width: 9px;
	height: 9px;
	border-radius: 50%;
	flex-shrink: 0;
	background: var(--pid-color, var(--outline-variant));
}

@keyframes spin-once {
	/* Replay icon spin tied to the replay button state. */
	from { transform: rotate(0deg); }
	to { transform: rotate(360deg); }
}

.btn-replaying .icon-small {
	animation: spin-once 0.5s ease-out;
}

/* PID color map */
.pid-color-1 { --pid-color: #004ac6; }
.pid-color-2 { --pid-color: #943700; }
.pid-color-3 { --pid-color: #059669; }
.pid-color-4 { --pid-color: #7c3aed; }
.pid-color-5 { --pid-color: #d97706; }
.pid-color-6 { --pid-color: #0891b2; }
.pid-color-7 { --pid-color: #dc2626; }
.pid-color-8 { --pid-color: #db2777; }
.pid-color-9 { --pid-color: #65a30d; }
.pid-color-10 { --pid-color: #0d9488; }
.pid-color-idle { --pid-color: #c3c6d7; }

/* Desktop breakpoint */
@media (min-width: 900px) {
	/* Two-column layout on larger screens. */
	.app-shell {
		grid-template-columns: minmax(320px, 1fr) minmax(0, 2fr);
	}

	.metrics-grid {
		grid-template-columns: repeat(2, minmax(0, 1fr));
	}
}

@media (max-width: 960px) {
	.topbar {
		padding: 0 var(--space-4);
	}
}

@media (max-width: 640px) {
	/* Compact spacing for narrow viewports. */
	.app-main {
		padding: 5.5rem 1rem 2rem;
	}

	.config-section,
	.panel-actions,
	.simulation-empty,
	.metric-card {
		padding: var(--space-5);
	}

	.results-table td {
		padding: 0.85rem 1rem;
	}

	.site-footer {
		padding: 0 1rem 0.5rem;
	}
}