:root {
	--bg: #f7f7fa;
	--panel: #ffffff;
	--border: #e2e2e8;
	--text: #1c1c22;
	--muted: #6b6b76;
	--accent: #4f5df0;
	--accent-text: #ffffff;
	--correct-bg: #e4f7ec;
	--correct-border: #34a853;
	--incorrect-bg: #fdeaea;
	--incorrect-border: #e0453c;
	--cat-containers: #1a73e8;
	--cat-data-management: #9333ea;
	--cat-connect-consume: #d97706;
	--cat-secure-monitor-troubleshoot: #dc2626;
	--cat-none: #6b6b76;
	--selected-bg: rgba(79, 93, 240, 0.08);
}

@media (prefers-color-scheme: dark) {
	:root {
		--bg: #17171c;
		--panel: #1f1f26;
		--border: #333340;
		--text: #ececf1;
		--muted: #9a9aa5;
		--accent: #7c86ff;
		--accent-text: #10101a;
		--correct-bg: #113322;
		--correct-border: #34a853;
		--incorrect-bg: #3a1414;
		--incorrect-border: #e0453c;
		--cat-containers: #5b9dff;
		--cat-data-management: #c084fc;
		--cat-connect-consume: #f2a93c;
		--cat-secure-monitor-troubleshoot: #f37272;
		--cat-none: #9a9aa5;
		--selected-bg: rgba(124, 134, 255, 0.16);
	}
}

* {
	box-sizing: border-box;
}

.hidden {
	display: none !important;
}

body {
	margin: 0;
	font-family: system-ui, -apple-system, 'Segoe UI', sans-serif;
	background: var(--bg);
	color: var(--text);
}

.app {
	display: flex;
	flex-direction: column;
	height: 100vh;
}

.topbar {
	display: flex;
	align-items: center;
	gap: 1rem;
	padding: 0.75rem 1.25rem;
	border-bottom: 1px solid var(--border);
	background: var(--panel);
}

.topbar h1 {
	font-size: 1.1rem;
	margin: 0;
	flex: 1;
}

.mode-toggle {
	display: flex;
	border: 1px solid var(--border);
	border-radius: 8px;
	overflow: hidden;
}

.mode-btn {
	border: none;
	background: transparent;
	color: var(--text);
	padding: 0.4rem 0.9rem;
	cursor: pointer;
	font-size: 0.9rem;
}

.mode-btn.active {
	background: var(--accent);
	color: var(--accent-text);
}

.ghost-btn {
	border: 1px solid var(--border);
	background: transparent;
	color: var(--muted);
	border-radius: 8px;
	padding: 0.4rem 0.8rem;
	cursor: pointer;
	font-size: 0.85rem;
}

.ghost-btn:hover {
	color: var(--text);
	border-color: var(--muted);
}

.body {
	display: flex;
	flex: 1;
	min-height: 0;
}

.sidebar {
	width: 340px;
	flex-shrink: 0;
	display: flex;
	flex-direction: column;
	border-right: 1px solid var(--border);
	background: var(--panel);
	padding: 0.75rem;
	min-height: 0;
}

#search,
#category-filter {
	padding: 0.5rem 0.7rem;
	border: 1px solid var(--border);
	border-radius: 8px;
	background: var(--bg);
	color: var(--text);
	font-size: 0.9rem;
}

#category-filter {
	margin-top: 0.5rem;
}

.count {
	color: var(--muted);
	font-size: 0.75rem;
	margin: 0.5rem 0.25rem;
}

.question-list {
	list-style: none;
	margin: 0;
	padding: 0;
	overflow-y: auto;
	flex: 1;
}

.q-item {
	display: flex;
	align-items: center;
	gap: 0.5rem;
	padding: 0.5rem 0.6rem;
	border-radius: 8px;
	cursor: pointer;
}

.q-item:hover {
	background: var(--bg);
}

.q-item.active {
	background: var(--accent);
	color: var(--accent-text);
}

.q-item.active .q-num,
.q-item.active .q-snippet {
	color: var(--accent-text);
}

.q-dot {
	width: 0.5rem;
	height: 0.5rem;
	border-radius: 50%;
	flex-shrink: 0;
	background: var(--cat-none);
}

.q-dot[data-category="containers"] {
	background: var(--cat-containers);
}

.q-dot[data-category="data-management"] {
	background: var(--cat-data-management);
}

.q-dot[data-category="connect-consume"] {
	background: var(--cat-connect-consume);
}

.q-dot[data-category="secure-monitor-troubleshoot"] {
	background: var(--cat-secure-monitor-troubleshoot);
}

.q-num {
	color: var(--muted);
	font-variant-numeric: tabular-nums;
	font-size: 0.8rem;
	width: 1.6rem;
	flex-shrink: 0;
}

.q-snippet {
	flex: 1;
	font-size: 0.85rem;
	white-space: nowrap;
	overflow: hidden;
	text-overflow: ellipsis;
}

.q-status {
	font-size: 0.85rem;
	width: 1rem;
	flex-shrink: 0;
	text-align: center;
}

.q-status.ok {
	color: var(--correct-border);
}

.q-status.bad {
	color: var(--incorrect-border);
}

.q-item.active .q-status.ok,
.q-item.active .q-status.bad {
	color: var(--accent-text);
}

.detail {
	flex: 1;
	display: flex;
	flex-direction: column;
	min-height: 0;
	padding: 1rem 1.5rem;
	overflow-y: auto;
}

.nav-row {
	display: flex;
	align-items: center;
	gap: 1rem;
	margin-bottom: 1rem;
}

.nav-btn {
	border: 1px solid var(--border);
	background: var(--panel);
	color: var(--text);
	border-radius: 8px;
	padding: 0.4rem 0.9rem;
	cursor: pointer;
}

.nav-btn:disabled {
	opacity: 0.4;
	cursor: default;
}

.position-label {
	color: var(--muted);
	font-size: 0.85rem;
}

.question-card {
	max-width: 760px;
	background: var(--panel);
	border: 1px solid var(--border);
	border-radius: 12px;
	padding: 1.5rem;
}

.empty-state {
	color: var(--muted);
}

.q-meta {
	display: flex;
	align-items: center;
	gap: 0.6rem;
	color: var(--muted);
	font-size: 0.8rem;
	margin-bottom: 0.5rem;
}

.category-badge {
	display: inline-block;
	padding: 0.15rem 0.55rem;
	border-radius: 999px;
	font-size: 0.72rem;
	font-weight: 600;
	color: #fff;
	background: var(--cat-none);
}

.category-badge[data-category="containers"] {
	background: var(--cat-containers);
}

.category-badge[data-category="data-management"] {
	background: var(--cat-data-management);
}

.category-badge[data-category="connect-consume"] {
	background: var(--cat-connect-consume);
}

.category-badge[data-category="secure-monitor-troubleshoot"] {
	background: var(--cat-secure-monitor-troubleshoot);
}

.q-text {
	font-size: 1.05rem;
	line-height: 1.5;
	margin-bottom: 1.25rem;
}

.choices {
	list-style: none;
	margin: 0 0 1.25rem;
	padding: 0;
	display: flex;
	flex-direction: column;
	gap: 0.5rem;
}

.choice {
	display: flex;
	gap: 0.6rem;
	align-items: flex-start;
	border: 1px solid var(--border);
	border-radius: 8px;
	padding: 0.6rem 0.8rem;
	line-height: 1.4;
}

.choice.selectable {
	cursor: pointer;
}

.choice.selectable:hover {
	border-color: var(--accent);
}

.choice.correct {
	background: var(--correct-bg);
	border-color: var(--correct-border);
}

.choice.incorrect {
	background: var(--incorrect-bg);
	border-color: var(--incorrect-border);
}

.choice.selected {
	background: var(--selected-bg);
	border-color: var(--accent);
}

.choice-label {
	font-weight: 600;
	color: var(--muted);
	flex-shrink: 0;
}

.practice-hint {
	color: var(--muted);
	font-size: 0.85rem;
	font-style: italic;
}

.explanation {
	border-top: 1px solid var(--border);
	padding-top: 1rem;
	white-space: pre-line;
	line-height: 1.55;
	color: var(--text);
	font-size: 0.92rem;
}

/* ===== Mock Exam ===== */

.exam-section {
	flex: 1;
	min-height: 0;
	overflow-y: auto;
	padding: 1.5rem;
}

.exam-stage {
	max-width: 900px;
	margin: 0 auto;
	padding-bottom: 2rem;
}

.exam-stage h2 {
	margin: 0 0 0.5rem;
}

.exam-config {
	display: flex;
	gap: 2.5rem;
	flex-wrap: wrap;
	margin: 1.5rem 0;
}

.config-group {
	display: flex;
	flex-direction: column;
	gap: 0.6rem;
}

.config-label {
	font-weight: 600;
	font-size: 0.9rem;
}

.preset-row {
	display: flex;
	gap: 0.5rem;
	flex-wrap: wrap;
}

.preset-btn {
	border: 1px solid var(--border);
	background: var(--panel);
	color: var(--text);
	border-radius: 8px;
	padding: 0.5rem 1rem;
	cursor: pointer;
	font-size: 0.9rem;
}

.preset-btn.active {
	background: var(--accent);
	color: var(--accent-text);
	border-color: var(--accent);
}

.custom-label {
	display: flex;
	align-items: center;
	gap: 0.5rem;
	font-size: 0.85rem;
	color: var(--muted);
}

.custom-label input {
	width: 90px;
	padding: 0.35rem 0.5rem;
	border: 1px solid var(--border);
	border-radius: 6px;
	background: var(--bg);
	color: var(--text);
}

.composition-preview {
	color: var(--muted);
	font-size: 0.85rem;
	margin: 1rem 0;
	min-height: 1.2em;
}

.primary-btn {
	background: var(--accent);
	color: var(--accent-text);
	border: none;
	border-radius: 8px;
	padding: 0.65rem 1.4rem;
	font-size: 0.95rem;
	cursor: pointer;
}

.primary-btn:disabled {
	opacity: 0.4;
	cursor: default;
}

.exam-history {
	margin-top: 2.5rem;
}

.exam-history h3 {
	font-size: 0.95rem;
	margin-bottom: 0.5rem;
}

.history-list {
	list-style: none;
	margin: 0;
	padding: 0;
	display: flex;
	flex-direction: column;
	gap: 0.4rem;
}

.history-item {
	display: flex;
	justify-content: space-between;
	gap: 1rem;
	padding: 0.5rem 0.75rem;
	border: 1px solid var(--border);
	border-radius: 8px;
	font-size: 0.85rem;
}

.history-score {
	font-variant-numeric: tabular-nums;
	white-space: nowrap;
}

.history-score.ok {
	color: var(--correct-border);
	font-weight: 600;
}

.history-score.bad {
	color: var(--incorrect-border);
	font-weight: 600;
}

.exam-header {
	display: flex;
	align-items: center;
	gap: 1rem;
	flex-wrap: wrap;
	margin-bottom: 1.25rem;
}

.exam-timer {
	font-variant-numeric: tabular-nums;
	font-size: 1.15rem;
	font-weight: 700;
	padding: 0.3rem 0.75rem;
	border-radius: 8px;
	background: var(--panel);
	border: 1px solid var(--border);
}

.exam-timer.warning {
	color: #fff;
	background: var(--incorrect-border);
	border-color: var(--incorrect-border);
}

.danger-btn {
	border-color: var(--incorrect-border);
	color: var(--incorrect-border);
}

.danger-btn:hover {
	background: var(--incorrect-bg);
}

.ghost-btn.active {
	background: var(--accent);
	color: var(--accent-text);
	border-color: var(--accent);
}

.exam-palette {
	display: flex;
	flex-wrap: wrap;
	gap: 0.4rem;
	margin-bottom: 1.5rem;
}

.palette-btn {
	width: 2.2rem;
	height: 2.2rem;
	border-radius: 6px;
	border: 1px solid var(--border);
	background: var(--panel);
	color: var(--text);
	cursor: pointer;
	font-size: 0.85rem;
	font-variant-numeric: tabular-nums;
}

.palette-btn.answered {
	background: var(--correct-bg);
	border-color: var(--correct-border);
}

.palette-btn.flagged {
	border-color: #d97706;
	border-width: 2px;
}

.palette-btn.current {
	outline: 2px solid var(--accent);
	outline-offset: 2px;
}

.results-summary {
	margin-bottom: 1.5rem;
}

.score-card {
	max-width: 320px;
	padding: 1.5rem;
	border-radius: 12px;
	text-align: center;
	border: 1px solid var(--border);
}

.score-card.pass {
	background: var(--correct-bg);
	border-color: var(--correct-border);
}

.score-card.fail {
	background: var(--incorrect-bg);
	border-color: var(--incorrect-border);
}

.score-big {
	font-size: 2.5rem;
	font-weight: 800;
}

.score-sub {
	color: var(--muted);
	font-size: 0.9rem;
	margin-top: 0.4rem;
}

.results-breakdown {
	display: flex;
	flex-direction: column;
	gap: 0.75rem;
	margin-bottom: 2rem;
	max-width: 700px;
}

.breakdown-row {
	display: flex;
	align-items: center;
	gap: 0.75rem;
	font-size: 0.85rem;
}

.breakdown-label {
	flex: 0 0 260px;
	color: var(--text);
}

.breakdown-bar {
	flex: 1;
	height: 0.6rem;
	background: var(--border);
	border-radius: 999px;
	overflow: hidden;
}

.breakdown-fill {
	height: 100%;
	background: var(--cat-none);
}

.breakdown-fill[data-category="containers"] {
	background: var(--cat-containers);
}

.breakdown-fill[data-category="data-management"] {
	background: var(--cat-data-management);
}

.breakdown-fill[data-category="connect-consume"] {
	background: var(--cat-connect-consume);
}

.breakdown-fill[data-category="secure-monitor-troubleshoot"] {
	background: var(--cat-secure-monitor-troubleshoot);
}

.breakdown-count {
	flex: 0 0 50px;
	text-align: right;
	color: var(--muted);
	font-variant-numeric: tabular-nums;
}

.results-review {
	display: flex;
	flex-direction: column;
	gap: 0.5rem;
	max-width: 760px;
}

.review-item {
	border: 1px solid var(--border);
	border-radius: 8px;
	padding: 0.25rem 0.75rem;
	background: var(--panel);
}

.review-item summary {
	cursor: pointer;
	padding: 0.6rem 0;
	display: flex;
	align-items: center;
	gap: 0.6rem;
	font-size: 0.9rem;
}

.review-icon {
	font-weight: 700;
	flex-shrink: 0;
}

.review-icon.ok {
	color: var(--correct-border);
}

.review-icon.bad {
	color: var(--incorrect-border);
}

.review-flag {
	margin-left: auto;
	flex-shrink: 0;
}

.review-body {
	padding: 0.5rem 0 1rem;
}

@media (max-width: 700px) {
	.body {
		flex-direction: column;
	}

	.sidebar {
		width: auto;
		max-height: 40vh;
		border-right: none;
		border-bottom: 1px solid var(--border);
	}

	.detail {
		padding: 1rem;
	}

	.exam-config {
		flex-direction: column;
		gap: 1.25rem;
	}

	.breakdown-label {
		flex-basis: 140px;
		font-size: 0.75rem;
	}
}