/* Copyright (c) 2026 abj. All rights reserved. */

/* ===================================================================
   LLD Problems — Style Sheet
   Slate + Blue dark theme (developer-focused)
   =================================================================== */

/* --- Design Tokens --- */
:root {
	--bg-base:        #1a1c23;
	--bg-raised:      #21242d;
	--bg-sunken:      #14161c;
	--text-primary:   #d1d5de;
	--text-soft:      rgba(209, 213, 222, 0.78);
	--text-muted:     rgba(209, 213, 222, 0.52);
	--text-faint:     rgba(209, 213, 222, 0.30);
	--text-heading:   #e2e6f0;
	--accent:         #7ec8c8;
	--accent-strong:  #a3dede;
	--accent-soft:    rgba(126, 200, 200, 0.08);
	--accent-line:    rgba(126, 200, 200, 0.25);
	--link:           #7ec8c8;
	--link-hover:     #a3dede;
	--code-bg:        rgba(0, 0, 0, 0.20);
	--code-text:      #a3dede;
	--border:         rgba(209, 213, 222, 0.08);
	--border-strong:  rgba(209, 213, 222, 0.14);
	--accent-border:  rgba(126, 200, 200, 0.20);
	--font-ui:        "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
	--font-body:      "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
	--font-display:   "Inter", -apple-system, BlinkMacSystemFont, sans-serif;
	--font-italic:    "Georgia", "Cambria", serif;
	--font-mono:      "SF Mono", Menlo, Consolas, monospace;
	--radius-sm:      6px;
	--radius-md:      8px;
	--radius-lg:      12px;
	--shadow-card:    0 4px 16px rgba(0, 0, 0, 0.3);
	--ease:           cubic-bezier(0.16, 1, 0.3, 1);
	--navbar-h:       56px;
	--sidebar-w:      300px;
}

/* --- Reset & Base --- */
*, *::before, *::after {
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}

html {
	font-size: 16px;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
}

body {
	font-family: var(--font-body);
	background: var(--bg-base);
	color: var(--text-primary);
	line-height: 1.65;
	min-height: 100vh;
	overflow-x: hidden;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
}


a {
	color: var(--link);
	text-decoration: none;
	transition: color 0.2s var(--ease);
}
a:hover {
	color: var(--link-hover);
}

::selection {
	background: var(--accent);
	color: var(--bg-base);
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
	width: 8px;
	height: 8px;
}
::-webkit-scrollbar-track {
	background: transparent;
}
::-webkit-scrollbar-thumb {
	background: var(--border-strong);
	border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
	background: var(--text-faint);
}

/* --- Navbar --- */
.navbar {
	position: fixed;
	top: 0;
	left: 0;
	right: 0;
	height: var(--navbar-h);
	z-index: 1000;
	display: flex;
	align-items: center;
	justify-content: space-between;
	padding: 0 24px;
	background: var(--bg-raised);
	border-bottom: 1px solid var(--border);
}

.navbar-brand {
	display: flex;
	align-items: center;
	gap: 10px;
	text-decoration: none;
	color: inherit;
}
.navbar-brand:hover {
	color: inherit;
}
.navbar-brand:hover .navbar-title {
	color: var(--accent);
}

.navbar-logo {
	color: var(--accent);
	font-size: 1.3rem;
}

.navbar-title {
	font-family: var(--font-display);
	font-weight: 700;
	font-size: 1.1rem;
	color: var(--text-heading);
	letter-spacing: -0.02em;
}

.navbar-links {
	display: flex;
	align-items: center;
	gap: 8px;
}

.nav-link {
	font-family: var(--font-ui);
	font-size: 0.82rem;
	font-weight: 500;
	padding: 0.5rem 0.85rem;
	border-radius: 8px;
	color: var(--text-muted);
	letter-spacing: -0.005em;
	transition: color 0.2s ease, background 0.2s ease;
}
.nav-link:hover {
	color: var(--text-primary);
	background: var(--border);
}
.nav-link.active {
	color: var(--text-primary);
}

.mobile-hamburger {
	display: none;
	flex-direction: column;
	gap: 5px;
	background: none;
	border: none;
	cursor: pointer;
	padding: 8px;
}
.mobile-hamburger span {
	display: block;
	width: 22px;
	height: 2px;
	background: var(--text-soft);
	border-radius: 2px;
	transition: all 0.3s var(--ease);
}

/* --- Layout --- */
.layout {
	display: flex;
	padding-top: var(--navbar-h);
	min-height: 100vh;
}

/* --- Sidebar --- */
.sidebar {
	position: fixed;
	top: var(--navbar-h);
	left: 0;
	bottom: 0;
	width: var(--sidebar-w);
	background: var(--bg-raised);
	border-right: 1px solid var(--border);
	z-index: 900;
	display: flex;
	flex-direction: column;
	overflow: hidden;
	transition: transform 0.35s var(--ease);
}

.sidebar-inner {
	display: flex;
	flex-direction: column;
	height: 100%;
	overflow: hidden;
}

.sidebar-overlay {
	display: none;
	position: fixed;
	inset: 0;
	background: rgba(0, 0, 0, 0.6);
	z-index: 899;
}

/* --- Sidebar Search --- */
.sidebar-search {
	position: relative;
	padding: 16px 16px 0;
}

.search-icon {
	position: absolute;
	left: 28px;
	top: 16px;
	margin-top: 12px;
	width: 16px;
	height: 16px;
	color: var(--text-muted);
	pointer-events: none;
}

#search-input {
	width: 100%;
	padding: 10px 12px 10px 38px;
	background: var(--bg-sunken);
	border: 1px solid var(--border);
	border-radius: var(--radius-sm);
	color: var(--text-primary);
	font-family: var(--font-ui);
	font-size: 0.85rem;
	outline: none;
	transition: border-color 0.2s var(--ease);
}
#search-input::placeholder {
	color: var(--text-faint);
}
#search-input:focus {
	border-color: var(--accent-line);
}

/* --- Sidebar Filters --- */
.sidebar-filters {
	padding: 12px 16px;
	display: flex;
	flex-direction: column;
	gap: 8px;
}

.filter-chips {
	display: flex;
	flex-wrap: wrap;
	gap: 6px;
}

.chip {
	font-family: var(--font-ui);
	font-size: 0.72rem;
	font-weight: 500;
	padding: 4px 10px;
	border-radius: 100px;
	border: 1px solid var(--border-strong);
	background: transparent;
	color: var(--text-soft);
	cursor: pointer;
	transition: all 0.2s var(--ease);
	white-space: nowrap;
}
.chip:hover {
	border-color: var(--accent-line);
	color: var(--text-primary);
}
.chip.active {
	border-color: var(--accent);
	background: var(--accent-soft);
	color: var(--accent);
}
.chip-easy.active {
	border-color: #3fb950;
	background: rgba(63, 185, 80, 0.12);
	color: #56d364;
}
.chip-medium.active {
	border-color: #d29922;
	background: rgba(210, 153, 34, 0.12);
	color: #e3b341;
}
.chip-hard.active {
	border-color: #f85149;
	background: rgba(248, 81, 73, 0.12);
	color: #ff7b72;
}

.pattern-chips {
	max-height: 60px;
	overflow-y: auto;
}

/* --- Sidebar Progress --- */
.sidebar-progress {
	padding: 0 16px 12px;
	display: flex;
	align-items: center;
	gap: 10px;
}

.progress-bar {
	flex: 1;
	height: 4px;
	background: var(--border);
	border-radius: 2px;
	overflow: hidden;
}

.progress-fill {
	height: 100%;
	background: linear-gradient(90deg, var(--accent), var(--accent-strong));
	border-radius: 2px;
	transition: width 0.4s var(--ease);
	width: 0%;
}

.progress-text {
	font-family: var(--font-ui);
	font-size: 0.72rem;
	color: var(--text-muted);
	white-space: nowrap;
}

/* --- Folder Tree --- */
.folder-tree {
	flex: 1;
	overflow-y: auto;
	padding: 0 8px 16px;
}

.tree-problem {
	margin-bottom: 2px;
}

.tree-problem-header {
	display: flex;
	align-items: center;
	gap: 6px;
	padding: 8px 12px;
	border-radius: var(--radius-sm);
	cursor: pointer;
	transition: all 0.15s var(--ease);
	user-select: none;
}
.tree-problem-header:hover {
	background: var(--accent-soft);
}
.tree-problem-header.active {
	background: var(--accent-soft);
	color: var(--accent);
}

.tree-arrow {
	width: 20px;
	height: 20px;
	display: flex;
	align-items: center;
	justify-content: center;
	flex-shrink: 0;
	color: var(--text-faint);
	transition: transform 0.2s var(--ease), color 0.2s var(--ease);
	font-size: 0.7rem;
	cursor: pointer;
	border-radius: var(--radius-sm);
}
.tree-arrow:hover {
	color: var(--accent);
	background: var(--accent-soft);
}
.tree-arrow.expanded {
	transform: rotate(90deg);
}

.tree-problem-name {
	font-family: var(--font-ui);
	font-size: 0.82rem;
	font-weight: 500;
	color: var(--text-soft);
	flex: 1;
	white-space: nowrap;
	overflow: hidden;
	text-overflow: ellipsis;
	cursor: pointer;
	transition: color 0.15s var(--ease);
}
.tree-problem-name:hover {
	color: var(--text-primary);
}
.tree-problem-header.active .tree-problem-name {
	color: var(--accent);
}

.tree-check {
	width: 14px;
	height: 14px;
	color: var(--accent);
	flex-shrink: 0;
	opacity: 0;
	transition: opacity 0.2s;
}
.tree-check.completed {
	opacity: 1;
}

.tree-difficulty {
	width: 8px;
	height: 8px;
	border-radius: 50%;
	flex-shrink: 0;
}
.tree-difficulty.easy { background: #3fb950; }
.tree-difficulty.medium { background: #d29922; }
.tree-difficulty.hard { background: #f85149; }

/* File tree (nested) — animated expand/collapse */
.tree-files {
	padding-left: 20px;
	max-height: 0;
	overflow: hidden;
	opacity: 0;
	transition: max-height 0.25s var(--ease), opacity 0.2s var(--ease);
}
.tree-files.open {
	max-height: 4000px;
	opacity: 1;
}

.tree-folder {
	margin-top: 2px;
}

.tree-folder-label {
	display: flex;
	align-items: center;
	gap: 4px;
	padding: 4px 8px;
	font-family: var(--font-mono);
	font-size: 0.72rem;
	color: var(--text-muted);
	cursor: pointer;
	border-radius: var(--radius-sm);
	transition: all 0.15s var(--ease);
}
.tree-folder-label:hover {
	color: var(--text-soft);
	background: rgba(209, 213, 222, 0.04);
}

.tree-folder-children {
	display: none;
	padding-left: 14px;
}
.tree-folder-children.open {
	display: block;
}

.tree-file {
	display: flex;
	align-items: center;
	gap: 6px;
	padding: 3px 8px;
	font-family: var(--font-mono);
	font-size: 0.72rem;
	color: var(--text-soft);
	cursor: pointer;
	border-radius: var(--radius-sm);
	transition: all 0.15s var(--ease);
}
.tree-file:hover {
	color: var(--accent);
	background: var(--accent-soft);
}
.tree-file.active {
	color: var(--accent);
	background: var(--accent-soft);
}

.tree-file-icon {
	width: 12px;
	height: 12px;
	flex-shrink: 0;
	opacity: 0.6;
}

/* --- Main Content --- */
.main-content {
	margin-left: var(--sidebar-w);
	flex: 1;
	min-width: 0;
	height: calc(100vh - var(--navbar-h));
	padding: 32px 40px 48px;
	overflow-x: hidden;
	overflow-y: auto;
	scroll-behavior: smooth;
}

.view {
	animation: fadeInUp 0.3s var(--ease);
}

@keyframes fadeInUp {
	from {
		opacity: 0;
		transform: translateY(12px);
	}
	to {
		opacity: 1;
		transform: translateY(0);
	}
}

/* --- Welcome View --- */
.welcome-hero {
	max-width: 640px;
	margin: 80px auto;
	text-align: center;
}

.welcome-title {
	font-family: var(--font-display);
	font-size: clamp(2.4rem, 5vw, 3.2rem);
	font-weight: 700;
	color: var(--text-heading);
	letter-spacing: -0.03em;
	line-height: 1.1;
	margin-bottom: 20px;
}
.welcome-title em {
	font-family: var(--font-italic);
	font-style: italic;
	font-weight: 300;
	color: var(--accent);
}

.welcome-subtitle {
	font-size: 0.95rem;
	color: var(--text-muted);
	letter-spacing: 0.01em;
	margin: 0 auto 40px;
}

.welcome-stats {
	display: flex;
	gap: 24px;
	justify-content: center;
	flex-wrap: wrap;
}

.stat-card {
	background: var(--bg-raised);
	border: 1px solid var(--border);
	border-radius: var(--radius-md);
	padding: 20px 28px;
	text-align: center;
	box-shadow: var(--shadow-card);
}

.stat-number {
	font-family: var(--font-display);
	font-size: 2rem;
	font-weight: 700;
	color: var(--accent);
	line-height: 1;
}

.stat-label {
	font-family: var(--font-ui);
	font-size: 0.78rem;
	color: var(--text-muted);
	margin-top: 6px;
	text-transform: uppercase;
	letter-spacing: 0.05em;
}

/* --- Welcome Author --- */
.welcome-author {
	margin-top: 48px;
	padding-top: 32px;
	border-top: 1px solid var(--border);
	display: flex;
	align-items: center;
	gap: 16px;
	justify-content: center;
}
.author-avatar {
	width: 52px;
	height: 52px;
	border-radius: 50%;
	object-fit: cover;
	border: 2px solid var(--border-strong);
	flex-shrink: 0;
}
.author-info {
	text-align: left;
}
.author-name {
	font-family: var(--font-ui);
	font-size: 0.9rem;
	font-weight: 600;
}
.author-name a {
	color: var(--text-heading);
	text-decoration: none;
}
.author-name a:hover {
	color: var(--accent);
}
.author-role {
	font-size: 0.78rem;
	color: var(--text-muted);
	margin-top: 2px;
}
.author-links {
	font-size: 0.75rem;
	margin-top: 4px;
	display: flex;
	align-items: center;
	gap: 6px;
}
.author-links a {
	color: var(--text-faint);
	transition: color 0.2s ease;
}
.author-links a:hover {
	color: var(--accent);
}
.author-links span {
	color: var(--text-faint);
}

/* --- Support Section --- */
.support-section {
	margin-top: 32px;
	border: 1px solid var(--border);
	border-radius: var(--radius-md);
	overflow: hidden;
	transition: border-color 0.3s ease;
}
.support-section:has(.support-embed.open) {
	border-color: rgba(255, 221, 87, 0.25);
}
.support-toggle {
	display: flex;
	align-items: center;
	gap: 10px;
	width: 100%;
	padding: 14px 18px;
	background: var(--bg-raised);
	border: none;
	cursor: pointer;
	text-align: left;
	transition: background 0.2s ease;
}
.support-toggle:hover {
	background: rgba(255, 221, 87, 0.04);
}
.support-icon {
	font-size: 1.1rem;
	flex-shrink: 0;
}
.support-text {
	font-family: var(--font-ui);
	font-size: 0.82rem;
	color: var(--text-muted);
	flex: 1;
}
.support-toggle:hover .support-text {
	color: var(--text-soft);
}
.support-chevron {
	color: var(--text-faint);
	flex-shrink: 0;
	transition: transform 0.3s ease, color 0.3s ease;
}
.support-section:has(.support-embed.open) .support-chevron {
	transform: rotate(180deg);
	color: #ffdd57;
}
.support-embed {
	max-height: 0;
	overflow: hidden;
	transition: max-height 0.35s ease;
}
.support-embed.open {
	max-height: 620px;
}
.support-embed > iframe {
	width: 100%;
	height: 600px;
	border: none;
	border-top: 1px solid var(--border);
	background: #fff;
	border-radius: 0 0 var(--radius-md) var(--radius-md);
}
@media (max-width: 480px) {
	.support-embed > iframe {
		height: 520px;
	}
	.support-toggle {
		padding: 12px 14px;
	}
	.support-text {
		font-size: 0.78rem;
	}
}

/* --- Footer --- */
.site-footer {
	position: fixed;
	bottom: 0;
	left: var(--sidebar-w);
	right: 0;
	z-index: 50;
	padding: 10px 24px;
	background: var(--bg-raised);
	border-top: 1px solid var(--border);
}
.footer-inner {
	display: flex;
	align-items: center;
	justify-content: space-between;
	gap: 16px;
}
.footer-author {
	display: flex;
	align-items: center;
	gap: 8px;
	font-size: 0.78rem;
}
.footer-name {
	color: var(--text-soft);
	font-weight: 600;
}
.footer-sep {
	color: var(--text-faint);
}
.footer-author a {
	color: var(--text-muted);
	transition: color 0.2s ease;
}
.footer-author a:hover {
	color: var(--accent);
}
.footer-note {
	font-size: 0.72rem;
	color: var(--text-faint);
}

@media (max-width: 768px) {
	.site-footer {
		left: 0;
	}
	.footer-inner {
		flex-direction: column;
		gap: 4px;
	}
	.footer-note {
		display: none;
	}
}

/* --- Problem View --- */
.problem-header {
	margin-bottom: 32px;
	padding-bottom: 24px;
	border-bottom: 1px solid var(--border);
}

.problem-title-row {
	display: flex;
	align-items: center;
	gap: 16px;
	margin-bottom: 12px;
}

.problem-title {
	font-family: var(--font-display);
	font-size: clamp(1.8rem, 4vw, 2.4rem);
	font-weight: 700;
	color: var(--text-heading);
	letter-spacing: -0.02em;
}

.btn-progress {
	width: 36px;
	height: 36px;
	border-radius: 50%;
	border: 2px solid var(--border-strong);
	background: transparent;
	color: var(--text-faint);
	cursor: pointer;
	display: flex;
	align-items: center;
	justify-content: center;
	transition: all 0.2s var(--ease);
	flex-shrink: 0;
}
.btn-progress:hover {
	border-color: var(--accent);
	color: var(--accent);
}
.btn-progress.completed {
	border-color: var(--accent);
	background: var(--accent);
	color: var(--bg-base);
}

.problem-meta {
	display: flex;
	align-items: center;
	gap: 10px;
	flex-wrap: wrap;
}

.badge {
	font-family: var(--font-ui);
	font-size: 0.72rem;
	font-weight: 600;
	padding: 4px 12px;
	border-radius: 100px;
	text-transform: uppercase;
	letter-spacing: 0.04em;
}
.badge-easy {
	background: rgba(63, 185, 80, 0.12);
	color: #56d364;
	border: 1px solid rgba(63, 185, 80, 0.30);
}
.badge-medium {
	background: rgba(210, 153, 34, 0.12);
	color: #e3b341;
	border: 1px solid rgba(210, 153, 34, 0.30);
}
.badge-hard {
	background: rgba(248, 81, 73, 0.12);
	color: #ff7b72;
	border: 1px solid rgba(248, 81, 73, 0.30);
}

.pattern-tag {
	font-family: var(--font-ui);
	font-size: 0.72rem;
	font-weight: 500;
	padding: 4px 10px;
	border-radius: 100px;
	border: 1px solid var(--accent-border);
	color: var(--text-soft);
	background: transparent;
}

.practice-link {
	display: inline-flex;
	align-items: center;
	gap: 6px;
	font-family: var(--font-ui);
	font-size: 0.82rem;
	font-weight: 600;
	padding: 8px 18px;
	border-radius: var(--radius-sm);
	background: var(--accent);
	color: var(--bg-base);
	border: none;
	cursor: pointer;
	transition: all 0.2s var(--ease);
	text-decoration: none;
	margin-top: 16px;
}
.practice-link:hover {
	background: var(--accent-strong);
	color: var(--bg-base);
	transform: translateY(-1px);
	box-shadow: 0 4px 16px rgba(126, 200, 200, 0.20);
}

/* --- Quick Files (Jump to) --- */
.quick-files {
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	gap: 8px;
	margin-top: 14px;
}

.quick-files span {
	font-family: var(--font-ui);
	font-size: 0.75rem;
	font-weight: 500;
	color: var(--text-muted);
	text-transform: uppercase;
	letter-spacing: 0.04em;
}

.quick-files a {
	font-family: var(--font-mono);
	font-size: 0.72rem;
	font-weight: 500;
	padding: 3px 10px;
	border-radius: 100px;
	border: 1px solid var(--accent-border);
	color: var(--text-soft);
	background: transparent;
	text-decoration: none;
	transition: all 0.2s var(--ease);
}
.quick-files a:hover {
	border-color: var(--accent);
	color: var(--accent);
	background: var(--accent-soft);
}

/* --- Problem Body / Markdown --- */
.problem-body {
	max-width: 780px;
}

.problem-body .markdown-content {
	color: var(--text-soft);
	line-height: 1.75;
}

.markdown-content h1,
.markdown-content h2,
.markdown-content h3,
.markdown-content h4 {
	font-family: var(--font-display);
	color: var(--text-heading);
	margin-top: 2.5em;
	margin-bottom: 0.8em;
	letter-spacing: -0.02em;
	font-weight: 700;
	line-height: 1.3;
}
.markdown-content h1 { font-size: 1.9rem; }
.markdown-content h2 { font-size: 1.5rem; border-bottom: 1px solid var(--border); padding-bottom: 10px; }
.markdown-content h3 { font-size: 1.25rem; color: var(--accent); }
.markdown-content h4 { font-size: 1.1rem; }

.markdown-content p {
	margin-bottom: 1em;
}

.markdown-content ul,
.markdown-content ol {
	padding-left: 1.5em;
	margin-bottom: 1em;
}
.markdown-content li {
	margin-bottom: 0.3em;
}

.markdown-content blockquote {
	border-left: 2px solid var(--border-strong);
	padding: 0.25rem 0 0.25rem 1.5rem;
	margin: 1.5em 0;
	background: transparent;
	color: var(--text-muted);
	font-style: italic;
}

.markdown-content code {
	font-family: var(--font-mono);
	font-size: 0.88em;
	background: var(--code-bg);
	color: var(--code-text);
	padding: 0.15em 0.4em;
	border-radius: 4px;
}

.markdown-content pre {
	background: var(--code-bg);
	border: 1px solid var(--border);
	border-radius: var(--radius-md);
	padding: 1.1rem 1.3rem;
	margin: 1.5em 0;
	overflow-x: auto;
	tab-size: 4;
	-moz-tab-size: 4;
	line-height: 1.55;
}
.markdown-content pre code {
	background: none;
	padding: 0;
	font-size: 0.85rem;
	color: var(--code-text);
	white-space: pre;
	tab-size: 4;
	-moz-tab-size: 4;
}

.markdown-content table {
	width: 100%;
	border-collapse: collapse;
	margin: 1em 0;
	font-size: 0.88rem;
}
.markdown-content th,
.markdown-content td {
	padding: 10px 14px;
	border: 1px solid var(--border);
	text-align: left;
}
.markdown-content th {
	background: var(--bg-sunken);
	color: var(--text-heading);
	font-weight: 600;
}
.markdown-content tr:hover td {
	background: rgba(209, 213, 222, 0.03);
}

.markdown-content hr {
	border: none;
	border-top: 1px solid var(--border);
	margin: 2em 0;
}

.markdown-content a {
	color: var(--link);
	text-decoration: underline;
	text-underline-offset: 2px;
}
.markdown-content a:hover {
	color: var(--link-hover);
}

/* --- Variations Section --- */
.variations-section {
	margin-top: 32px;
	padding-top: 24px;
	border-top: 1px solid var(--accent-border);
}

.variations-section h2 {
	color: var(--accent);
	font-family: var(--font-display);
	display: flex;
	align-items: center;
	gap: 8px;
}

/* --- Code Viewer --- */
.code-header {
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	gap: 10px 16px;
	padding-bottom: 16px;
	margin-bottom: 16px;
	border-bottom: 1px solid var(--border);
}

.code-breadcrumb {
	font-family: var(--font-mono);
	font-size: 0.82rem;
	color: var(--text-muted);
	display: flex;
	align-items: center;
	gap: 4px;
	flex-wrap: wrap;
	flex: 1 1 auto;
	min-width: 0;
}

.breadcrumb-segment {
	color: var(--text-soft);
	white-space: nowrap;
}
.breadcrumb-link {
	cursor: pointer;
	text-decoration: none;
	transition: color 0.15s var(--ease);
}
.breadcrumb-link:hover {
	color: var(--accent);
	text-decoration: underline;
	text-underline-offset: 2px;
}
.breadcrumb-separator {
	color: var(--text-faint);
	margin: 0 2px;
}
.breadcrumb-file {
	color: var(--accent);
	font-weight: 600;
	white-space: nowrap;
	overflow: hidden;
	text-overflow: ellipsis;
}
.breadcrumb-patterns {
	display: flex;
	align-items: center;
	gap: 5px;
	flex-wrap: wrap;
	margin-left: auto;
}
.breadcrumb-pattern-tag {
	font-family: var(--font-ui);
	font-size: 0.65rem;
	font-weight: 500;
	padding: 2px 8px;
	border-radius: 100px;
	border: 1px solid var(--accent-border);
	color: var(--accent);
	background: var(--accent-soft);
	white-space: nowrap;
}

.code-header-actions {
	display: flex;
	align-items: center;
	gap: 8px;
	flex-wrap: wrap;
	flex-shrink: 0;
}

.btn-copy, .btn-edit, .btn-save, .btn-reset, .btn-run, .btn-tests {
	display: flex;
	align-items: center;
	gap: 6px;
	font-family: var(--font-ui);
	font-size: 0.78rem;
	font-weight: 500;
	padding: 6px 14px;
	border-radius: var(--radius-sm);
	border: 1px solid var(--border-strong);
	background: transparent;
	color: var(--text-soft);
	cursor: pointer;
	transition: all 0.2s var(--ease);
}
.btn-copy svg, .btn-edit svg, .btn-save svg, .btn-reset svg, .btn-run svg, .btn-tests svg {
	width: 14px;
	height: 14px;
}
.btn-save {
	border-color: #3fb950;
	color: #56d364;
	background: rgba(63, 185, 80, 0.08);
}
.btn-save:hover {
	background: rgba(63, 185, 80, 0.15);
	color: #56d364;
}
.btn-save.saved {
	border-color: #56d364;
	background: rgba(63, 185, 80, 0.20);
	color: #56d364;
}
.btn-reset {
	border-color: var(--border-strong);
	color: var(--text-muted);
}
.btn-reset:hover {
	border-color: #f85149;
	color: #ff7b72;
	background: rgba(248, 81, 73, 0.08);
}
.btn-copy:hover, .btn-edit:hover, .btn-tests:hover {
	border-color: var(--accent-line);
	color: var(--accent);
}
.btn-run {
	background: var(--accent-soft);
	border-color: var(--accent-line);
	color: var(--accent);
}
.btn-run:hover {
	background: var(--accent);
	color: var(--bg-base);
}
.btn-run:disabled, .btn-tests:disabled {
	opacity: 0.5;
	cursor: not-allowed;
}
.btn-edit.active {
	background: var(--accent-soft);
	border-color: var(--accent);
	color: var(--accent);
}
.btn-copy.copied {
	border-color: #3fb950;
	color: #56d364;
}

/* Monaco editor container */
.code-editor {
	height: 60vh;
	min-height: 400px;
	width: 100%;
	border-radius: var(--radius-md);
	overflow: hidden;
}

/* Run output panel */
.run-panel {
	margin-top: 12px;
	background: var(--bg-sunken);
	border: 1px solid var(--border);
	border-radius: var(--radius-md);
	overflow: hidden;
}
.run-panel-header {
	display: flex;
	align-items: center;
	justify-content: space-between;
	padding: 10px 16px;
	background: var(--bg-raised);
	border-bottom: 1px solid var(--border);
}
.run-panel-title {
	font-family: var(--font-ui);
	font-size: 0.82rem;
	font-weight: 600;
	color: var(--text-primary);
}
.run-panel-title.ok { color: #56d364; }
.run-panel-title.fail { color: #f85149; }
.run-panel-close {
	background: none;
	border: none;
	color: var(--text-muted);
	font-size: 1.2rem;
	cursor: pointer;
	padding: 0 6px;
	line-height: 1;
}
.run-panel-close:hover { color: var(--text-primary); }
.run-panel-body {
	padding: 14px 16px;
	font-family: var(--font-mono);
	font-size: 0.78rem;
	color: var(--text-soft);
	max-height: 400px;
	overflow: auto;
	white-space: pre-wrap;
	word-break: break-word;
}
.run-panel-section + .run-panel-section {
	margin-top: 12px;
	padding-top: 12px;
	border-top: 1px dashed var(--border);
}
.run-panel-section-label {
	font-family: var(--font-ui);
	font-size: 0.7rem;
	text-transform: uppercase;
	letter-spacing: 0.08em;
	color: var(--text-faint);
	margin-bottom: 4px;
}
.run-panel-stderr { color: #ff7b72; }

/* Test case rows */
/* Test case results */
.test-case {
	border: 1px solid var(--border);
	border-radius: var(--radius-md);
	margin-bottom: 8px;
	overflow: hidden;
}
.test-case-header {
	display: flex;
	align-items: center;
	gap: 10px;
	padding: 10px 14px;
	background: var(--bg-raised);
}
.test-case-status {
	flex-shrink: 0;
	font-family: var(--font-mono);
	font-size: 0.7rem;
	font-weight: 700;
	text-transform: uppercase;
	letter-spacing: 0.04em;
	padding: 2px 8px;
	border-radius: 4px;
}
.test-case-status.pass {
	color: #56d364;
	background: rgba(63, 185, 80, 0.10);
}
.test-case-status.fail {
	color: #f85149;
	background: rgba(248, 81, 73, 0.10);
}
.test-case-status.skip {
	color: var(--text-faint);
}
.test-case-name {
	font-family: var(--font-ui);
	font-size: 0.82rem;
	font-weight: 500;
	color: var(--text-primary);
}

/* Test I/O detail body */
.test-case-body {
	padding: 10px 14px;
	display: flex;
	flex-direction: column;
	gap: 8px;
	border-top: 1px solid var(--border);
}
.test-case-body--fail {
	background: rgba(248, 81, 73, 0.03);
}
.test-io-row {
	display: grid;
	grid-template-columns: 72px 1fr;
	gap: 8px;
	align-items: start;
}
.test-io-label {
	font-family: var(--font-ui);
	font-size: 0.68rem;
	font-weight: 600;
	text-transform: uppercase;
	letter-spacing: 0.04em;
	color: var(--text-faint);
	padding-top: 4px;
}
.test-io-value {
	font-family: var(--font-mono);
	font-size: 0.75rem;
	line-height: 1.5;
	color: var(--text-soft);
	background: var(--code-bg);
	border-radius: var(--radius-sm);
	padding: 6px 10px;
	margin: 0;
	white-space: pre-wrap;
	word-break: break-word;
	max-height: 160px;
	overflow-y: auto;
}
.test-io-row--error .test-io-label {
	color: #ff7b72;
}
.test-io-row--error .test-io-value {
	color: #ff7b72;
	background: rgba(248, 81, 73, 0.06);
}

/* Responsive: stack on small screens */
@media (max-width: 600px) {
	.test-io-row {
		grid-template-columns: 1fr;
		gap: 2px;
	}
	.test-io-label {
		padding-top: 0;
	}
	.test-case-header {
		padding: 8px 10px;
	}
	.test-case-body {
		padding: 8px 10px;
	}
}

.code-container {
	background: var(--bg-sunken);
	border: 1px solid var(--border);
	border-radius: var(--radius-md);
	overflow: hidden;
	box-shadow: var(--shadow-card);
}

.code-container pre {
	margin: 0;
	padding: 20px;
	overflow-x: auto;
	tab-size: 4;
	-moz-tab-size: 4;
}

.code-container pre code {
	font-family: var(--font-mono);
	font-size: 0.82rem;
	line-height: 1.65;
	white-space: pre;
	tab-size: 4;
	-moz-tab-size: 4;
}

/* --- Prism.js Theme Override (Navy + Brass) --- */
code[class*="language-"],
pre[class*="language-"] {
	color: var(--text-soft);
	background: var(--bg-sunken);
	font-family: var(--font-mono);
	font-size: 0.82rem;
	line-height: 1.65;
	tab-size: 4;
	-moz-tab-size: 4;
	white-space: pre;
	word-spacing: normal;
	word-break: normal;
	word-wrap: normal;
	hyphens: none;
}

pre[class*="language-"] {
	padding: 20px;
	overflow: auto;
	border-radius: var(--radius-md);
}

/* Line numbers */
.line-numbers .line-numbers-rows {
	border-right: 1px solid var(--border);
	padding-right: 12px;
}
.line-numbers .line-numbers-rows > span::before {
	color: var(--text-faint);
}

pre[class*="language-"].line-numbers {
	padding-left: 3.8em;
}

/* Token colors (muted, easy on the eyes) */
.token.comment,
.token.prolog,
.token.doctype,
.token.cdata {
	color: #6b7280;
	font-style: italic;
}

.token.punctuation {
	color: #9ca3af;
}

.token.namespace {
	opacity: 0.7;
}

.token.property,
.token.tag,
.token.boolean,
.token.number,
.token.constant,
.token.symbol {
	color: #d4976c;
}

.token.selector,
.token.attr-name,
.token.string,
.token.char,
.token.builtin {
	color: #8abf8a;
}

.token.operator,
.token.entity,
.token.url {
	color: #c9a0dc;
}

.token.atrule,
.token.attr-value,
.token.keyword {
	color: #c9a0dc;
}

.token.function {
	color: #7ec8c8;
}

.token.class-name {
	color: #e2c07b;
}

.token.regex,
.token.important,
.token.variable {
	color: #d4976c;
}

.token.important,
.token.bold {
	font-weight: bold;
}

.token.italic {
	font-style: italic;
}

.token.annotation {
	color: #7ec8c8;
}

/* --- Responsive: Tablet landscape --- */
@media (max-width: 1024px) {
	:root {
		--sidebar-w: 240px;
	}
	.main-content {
		padding: 20px 24px;
	}
	.code-header {
		gap: 8px 12px;
	}
	.breadcrumb-patterns {
		margin-left: 0;
		flex-basis: 100%;
	}
}

/* --- Responsive: Tablet portrait / iPad --- */
@media (max-width: 768px) {
	.navbar-links {
		display: none;
	}
	.mobile-hamburger {
		display: flex;
	}

	.sidebar {
		transform: translateX(-100%);
		width: 300px;
	}
	.sidebar.open {
		transform: translateX(0);
	}
	.sidebar-overlay.open {
		display: block;
	}

	.main-content {
		margin-left: 0;
		padding: 20px 16px;
	}

	.welcome-title {
		font-size: 1.8rem;
	}

	.problem-title {
		font-size: 1.4rem;
	}

	.welcome-stats {
		flex-direction: row;
		flex-wrap: wrap;
		justify-content: center;
	}
	.stat-card {
		padding: 14px 18px;
	}

	/* Code header: stack into rows on tablet */
	.code-header {
		flex-direction: column;
		align-items: flex-start;
		gap: 10px;
	}
	.code-breadcrumb {
		width: 100%;
		font-size: 0.78rem;
	}
	.breadcrumb-patterns {
		margin-left: 0;
		flex-basis: 100%;
		order: 3;
	}
	.code-header-actions {
		width: 100%;
		justify-content: flex-start;
	}
}

/* --- Responsive: Mobile --- */
@media (max-width: 480px) {
	.main-content {
		padding: 14px 12px;
	}

	.welcome-title {
		font-size: 1.5rem;
	}

	.welcome-stats {
		flex-direction: column;
		align-items: stretch;
		gap: 8px;
	}
	.stat-card {
		padding: 12px 14px;
	}
	.stat-number {
		font-size: 1.5rem;
	}

	.code-breadcrumb {
		font-size: 0.72rem;
	}
	.breadcrumb-pattern-tag {
		font-size: 0.6rem;
		padding: 2px 6px;
	}
	.code-header-actions {
		gap: 6px;
	}
	.btn-copy, .btn-edit, .btn-save, .btn-reset, .btn-run, .btn-tests {
		padding: 5px 10px;
		font-size: 0.72rem;
	}
	.btn-copy span, .btn-edit span, .btn-save span, .btn-reset span, .btn-run span, .btn-tests span {
		display: none;
	}

	.problem-title {
		font-size: 1.2rem;
	}
	.problem-meta {
		gap: 6px;
	}
	.badge {
		font-size: 0.65rem;
		padding: 3px 8px;
	}
	.pattern-tag {
		font-size: 0.65rem;
		padding: 3px 8px;
	}
}

/* --- Folder Listing (GitHub-style directory view) --- */
.folder-listing {
	padding: 8px 0;
}

.folder-listing-header {
	display: flex;
	align-items: center;
	gap: 10px;
	padding: 12px 20px;
	border-bottom: 1px solid var(--border);
	font-family: var(--font-mono);
	font-size: 0.85rem;
	color: var(--text-soft);
}

.folder-listing-icon {
	width: 18px;
	height: 18px;
	color: var(--accent);
	flex-shrink: 0;
}

.folder-listing-count {
	margin-left: auto;
	font-size: 0.72rem;
	color: var(--text-muted);
}

.folder-listing-item {
	display: flex;
	align-items: center;
	gap: 12px;
	padding: 10px 20px;
	border-bottom: 1px solid var(--border);
	font-family: var(--font-mono);
	font-size: 0.82rem;
	color: var(--text-soft);
	text-decoration: none;
	transition: background 0.12s var(--ease);
	cursor: pointer;
}

.folder-listing-item:hover {
	background: var(--accent-soft);
	color: var(--accent);
}

.folder-listing-item:last-child {
	border-bottom: none;
}

.folder-listing-item svg {
	width: 16px;
	height: 16px;
	flex-shrink: 0;
	opacity: 0.7;
}

.folder-listing-folder svg {
	color: var(--accent);
	opacity: 1;
}

.folder-listing-badge {
	margin-left: auto;
	font-family: var(--font-ui);
	font-size: 0.62rem;
	font-weight: 500;
	padding: 2px 7px;
	border-radius: 100px;
	border: 1px solid var(--accent-border);
	color: var(--text-muted);
	background: transparent;
	white-space: nowrap;
}

.folder-listing-item:hover .folder-listing-badge {
	border-color: var(--accent-line);
	color: var(--accent);
}

/* --- IDE Features: Clickable Symbols + Tooltips --- */
.ide-link {
	color: var(--text-heading);
	text-decoration: underline;
	text-decoration-style: dotted;
	text-underline-offset: 3px;
	text-decoration-color: rgba(88, 166, 255, 0.4);
	border-radius: 2px;
	cursor: pointer;
	transition: all 0.12s ease;
}

.ide-link:hover {
	text-decoration-color: var(--accent);
	text-decoration-style: solid;
	background: rgba(126, 200, 200, 0.08);
	color: var(--accent-strong) !important;
	border-radius: 3px;
	padding: 0 2px;
	margin: 0 -2px;
}

/* Same-file links: subtle, no navigation cursor */
.ide-link.ide-link-same {
	text-decoration-color: rgba(209, 213, 222, 0.18);
	cursor: default;
}

.ide-link.ide-link-same:hover {
	text-decoration-color: rgba(209, 213, 222, 0.35);
	background: rgba(209, 213, 222, 0.05);
	color: var(--text-heading) !important;
}

.ide-tooltip {
	position: fixed;
	z-index: 9999;
	max-width: 560px;
	min-width: 300px;
	background: var(--bg-sunken);
	border: 1px solid var(--accent-border);
	border-radius: var(--radius-md);
	box-shadow: 0 12px 40px rgba(0, 0, 0, 0.6), 0 0 0 1px rgba(126, 200, 200, 0.06);
	padding: 0;
	overflow: hidden;
	opacity: 0;
	transition: opacity 0.15s ease;
	pointer-events: auto;
}

.ide-tooltip-header {
	display: flex;
	align-items: center;
	gap: 8px;
	padding: 8px 12px;
	background: rgba(126, 200, 200, 0.05);
	border-bottom: 1px solid var(--border);
}

.ide-tooltip-kind {
	font-family: var(--font-mono);
	font-size: 0.7rem;
	font-weight: 600;
	text-transform: uppercase;
	letter-spacing: 0.05em;
	color: var(--accent);
	background: rgba(126, 200, 200, 0.08);
	padding: 2px 7px;
	border-radius: 4px;
}

.ide-tooltip-file {
	font-family: var(--font-mono);
	font-size: 0.7rem;
	color: var(--text-muted);
}

.ide-tooltip-code {
	margin: 0;
	padding: 10px 12px;
	font-family: var(--font-mono);
	font-size: 0.72rem;
	line-height: 1.5;
	color: var(--text-soft);
	background: transparent;
	white-space: pre;
	overflow-x: auto;
	max-height: 200px;
	overflow-y: auto;
	border: none;
	border-radius: 0;
	scrollbar-width: thin;
	scrollbar-color: var(--accent-border) transparent;
}

.ide-tooltip-code code {
	font-family: inherit;
	font-size: inherit;
	background: none;
	padding: 0;
	color: inherit;
}

.ide-tooltip-hint {
	display: block;
	padding: 5px 12px 7px;
	font-family: var(--font-ui);
	font-size: 0.65rem;
	color: var(--text-faint);
	border-top: 1px solid var(--border);
	text-align: center;
}

.ide-tooltip-desc {
	padding: 8px 12px 10px;
	font-family: var(--font-ui);
	font-size: 0.78rem;
	line-height: 1.5;
	color: var(--text-soft);
}

.ide-tooltip-keyword {
	max-width: 340px;
	min-width: 200px;
}

.ide-keyword-hoverable {
	cursor: help;
}

.ide-hint {
	margin-left: auto;
	font-family: var(--font-ui);
	font-size: 0.65rem;
	color: var(--text-faint);
	font-style: italic;
	letter-spacing: 0.02em;
}

/* --- TOC Sidebar (right) --- */
.toc-sidebar {
	position: fixed;
	top: var(--navbar-h);
	right: 0;
	bottom: 0;
	width: 240px;
	padding: 28px 12px 52px 0;
	overflow-y: auto;
	display: none;
	scrollbar-width: thin;
	scrollbar-color: var(--border-strong) transparent;
}
.toc-sidebar.visible {
	display: flex;
	flex-direction: column;
}
.toc-inner {
	padding-left: 16px;
	border-left: 1px solid var(--border);
}
.toc-title {
	font-family: var(--font-ui);
	font-size: 0.68rem;
	font-weight: 600;
	text-transform: uppercase;
	letter-spacing: 0.08em;
	color: var(--text-faint);
	margin-bottom: 16px;
	padding-left: 10px;
}
.toc-nav {
	display: flex;
	flex-direction: column;
	gap: 1px;
}
.toc-link {
	font-family: var(--font-ui);
	font-size: 0.76rem;
	color: var(--text-muted);
	text-decoration: none;
	padding: 6px 10px;
	border-radius: var(--radius-sm);
	border-left: 2px solid transparent;
	margin-left: -1px;
	line-height: 1.45;
	transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
	cursor: pointer;
}
.toc-link:hover {
	color: var(--text-primary);
	background: rgba(209, 213, 222, 0.05);
}
.toc-link.active {
	color: var(--accent);
	border-left-color: var(--accent);
	background: var(--accent-soft);
}
.toc-link.toc-h3 {
	padding-left: 22px;
	font-size: 0.72rem;
	color: var(--text-faint);
}
.toc-link.toc-h3:hover {
	color: var(--text-muted);
}
.toc-link.toc-h3.active {
	color: var(--accent);
}

/* Heading highlight flash when clicked from TOC */
.toc-highlight {
	animation: toc-flash 1.5s ease;
}
@keyframes toc-flash {
	0% { background: var(--accent-soft); border-radius: var(--radius-sm); }
	100% { background: transparent; }
}

/* Adjust main content width when TOC is visible */
.main-content.has-toc {
	margin-right: 240px;
}

@media (max-width: 1280px) {
	.toc-sidebar {
		width: 200px;
	}
	.main-content.has-toc {
		margin-right: 200px;
	}
}
@media (max-width: 1024px) {
	.toc-sidebar {
		display: none !important;
	}
	.main-content.has-toc {
		margin-right: 0;
	}
}

/* --- Utility --- */
.hidden {
	display: none !important;
}

/* Focus visible for accessibility */
:focus-visible {
	outline: 2px solid var(--accent);
	outline-offset: 2px;
}