:root,
:root[data-theme='dark'] {
  color-scheme: dark;
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-accent: rgba(148, 163, 184, 0.1);
  --bg-accent-2: rgba(100, 116, 139, 0.12);
  --bg-gradient-start: #0f172a;
  --bg-gradient-end: #020617;
  --bg-card: rgba(15, 23, 42, 0.7);
  --surface-muted: rgba(148, 163, 184, 0.08);
  --surface-strong: rgba(15, 23, 42, 0.45);
  --surface-input: rgba(15, 23, 42, 0.85);
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-accent: #cbd5e1;
  --border-soft: rgba(148, 163, 184, 0.2);
  --code-bg: #1e293b;
  --code-border: #334155;
  --good-color: #10b981;
  --bad-color: #ef4444;
  --badge-bg: #334155;
  --warn-color: #f59e0b;
  --table-header-bg: rgba(86, 156, 214, 0.1);
  --table-row-hover: rgba(255, 255, 255, 0.02);
  --accent-soft: rgba(59, 130, 246, 0.2);
  --accent-strong: rgba(59, 130, 246, 0.6);
  --button-bg: rgba(148, 163, 184, 0.1);
  --button-border-hover: rgba(148, 163, 184, 0.5);
  --focus-ring: rgba(59, 130, 246, 0.6);
}

:root[data-theme='light'] {
  color-scheme: light;
  --bg-primary: #f8fafc;
  --bg-secondary: #e2e8f0;
  --bg-accent: rgba(59, 130, 246, 0.16);
  --bg-accent-2: rgba(14, 165, 233, 0.12);
  --bg-gradient-start: #f8fafc;
  --bg-gradient-end: #e2e8f0;
  --bg-card: rgba(255, 255, 255, 0.92);
  --surface-muted: rgba(15, 23, 42, 0.04);
  --surface-strong: rgba(15, 23, 42, 0.06);
  --surface-input: #ffffff;
  --text-main: #0f172a;
  --text-muted: #475569;
  --text-accent: #1e293b;
  --border-soft: rgba(15, 23, 42, 0.12);
  --code-bg: #f1f5f9;
  --code-border: #cbd5e1;
  --good-color: #16a34a;
  --bad-color: #dc2626;
  --badge-bg: #e2e8f0;
  --warn-color: #f59e0b;
  --table-header-bg: rgba(59, 130, 246, 0.08);
  --table-row-hover: rgba(15, 23, 42, 0.04);
  --accent-soft: rgba(37, 99, 235, 0.12);
  --accent-strong: rgba(37, 99, 235, 0.4);
  --button-bg: rgba(15, 23, 42, 0.04);
  --button-border-hover: rgba(15, 23, 42, 0.2);
  --focus-ring: rgba(37, 99, 235, 0.5);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  padding: clamp(1.5rem, 3vw, 3rem);
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background:
    radial-gradient(circle at 20% 20%, var(--bg-accent), transparent 60%),
    radial-gradient(circle at 80% 10%, var(--bg-accent-2), transparent 55%),
    linear-gradient(160deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
  color: var(--text-main);
  line-height: 1.6;
}

.app-shell {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(220px, 280px) minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 3rem);
  align-items: start;
}

.sidebar {
  position: sticky;
  top: clamp(1rem, 2vw, 2rem);
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: 1rem;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  max-height: calc(100vh - 4rem);
  overflow: auto;
}

.sidebar-header h1 {
  margin: 0.5rem 0 0.75rem 0;
  font-size: clamp(1.3rem, 2.8vw, 1.75rem);
}

.header-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.sidebar-subtitle {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.18em;
  font-size: 0.7rem;
  color: var(--text-muted);
  margin: 0;
}

.sidebar-section h2 {
  margin: 0 0 0.75rem 0;
  font-size: 1rem;
  color: var(--text-accent);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.topic-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.topic-group {
  border: 1px solid var(--border-soft);
  border-radius: 0.75rem;
  padding: 0.5rem 0.75rem;
  background: var(--surface-strong);
}

.topic-group summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--text-accent);
  list-style: none;
}

.topic-group summary::-webkit-details-marker {
  display: none;
}

.topic-questions {
  margin-top: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.question-link {
  text-align: left;
  border: 1px solid transparent;
  background: var(--surface-muted);
  color: var(--text-main);
  padding: 0.5rem 0.75rem;
  border-radius: 0.6rem;
  font-size: 0.85rem;
  line-height: 1.4;
  cursor: pointer;
  transition: border-color 0.2s ease, background 0.2s ease;
}

.question-link:hover {
  border-color: var(--button-border-hover);
}

.question-link.active {
  background: var(--accent-soft);
  border-color: var(--accent-strong);
}

.card-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: 1.25rem;
  padding: clamp(1.5rem, 3vw, 2.5rem);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.card-type-badge {
  background: var(--badge-bg);
  color: var(--text-accent);
  padding: 0.35rem 0.85rem;
  border-radius: 0.375rem;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  width: fit-content;
}

.card-type-badge.practice {
  background: linear-gradient(135deg, #38bdf8 0%, #2563eb 100%);
  color: white;
}

.card-header {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  justify-content: space-between;
}

.card-question {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  line-height: 1.3;
  margin: 0;
  font-weight: 700;
  color: var(--text-main);
  text-align: left;
}

.card-answer {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  text-align: left;
}

.card-answer.is-hidden {
  display: none;
}

.answer-text {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  line-height: 1.7;
  margin: 0;
  color: var(--text-accent);
}

.answer-list {
  font-size: clamp(1rem, 2.5vw, 1.2rem);
  line-height: 1.8;
  margin: 0.5rem 0;
  padding-left: 1.5rem;
  color: var(--text-accent);
}

.answer-list li {
  margin: 0.5rem 0;
  padding-left: 0.25rem;
}

.answer-list li::marker {
  color: var(--good-color);
}

.table-wrapper {
  margin: 1rem 0;
  overflow-x: auto;
  border-radius: 0.5rem;
  border: 1px solid var(--code-border);
}

.answer-table {
  width: 100%;
  border-collapse: collapse;
  font-size: clamp(0.85rem, 2vw, 1rem);
  background: var(--code-bg);
}

.answer-table th,
.answer-table td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--code-border);
}

.answer-table th {
  background: var(--table-header-bg);
  color: #569cd6;
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.85em;
  letter-spacing: 0.05em;
}

.answer-table tbody tr:hover {
  background: var(--table-row-hover);
}

.answer-table tbody tr:last-child td {
  border-bottom: none;
}

.code-wrapper {
  position: relative;
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: 0.5rem;
  overflow: hidden;
  margin: 0.5rem 0;
}

.code-wrapper.good {
  border-left: 4px solid var(--good-color);
}

.code-wrapper.bad {
  border-left: 4px solid var(--bad-color);
}

.code-badge {
  display: inline-block;
  padding: 0.4rem 0.8rem;
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: 0 0 0.375rem 0;
  position: absolute;
  top: 0;
  right: 0;
  z-index: 1;
}

.code-badge.good {
  background: var(--good-color);
  color: white;
}

.code-badge.bad {
  background: var(--bad-color);
  color: white;
}

pre {
  margin: 0;
  padding: 3rem 1.25rem 1.25rem 1.25rem;
  overflow-x: auto;
  font-family: 'JetBrains Mono', 'Consolas', 'Monaco', monospace;
  font-size: clamp(0.8rem, 1.8vw, 0.95rem);
  line-height: 1.6;
}

code {
  font-family: inherit;
  color: #dcdcdc;
}

/* Visual Studio Dark Theme Colors for C# */
code[class*="language-"],
pre[class*="language-"] {
  color: #dcdcdc;
  background: none;
  font-family: 'JetBrains Mono', 'Consolas', 'Monaco', monospace;
  text-align: left;
  white-space: pre;
  word-spacing: normal;
  word-break: normal;
  word-wrap: normal;
  line-height: 1.6;
  tab-size: 4;
}

/* Keywords: if, else, return, public, private, class, etc. */
.token.keyword {
  color: #569cd6;
}

/* Class names, types */
.token.class-name {
  color: #4ec9b0;
}

/* Strings */
.token.string {
  color: #d69d85;
}

/* Numbers */
.token.number {
  color: #b5cea8;
}

/* Comments */
.token.comment {
  color: #6a9955;
  font-style: italic;
}

/* Functions, method names */
.token.function {
  color: #dcdcaa;
}

/* Operators: =, +, -, etc. */
.token.operator {
  color: #d4d4d4;
}

.answer-check {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  padding: 1rem;
  border-radius: 0.85rem;
  background: var(--surface-strong);
  border: 1px solid var(--border-soft);
}

.answer-check label {
  font-weight: 600;
  color: var(--text-accent);
}

.answer-check textarea {
  resize: vertical;
  min-height: 120px;
  border-radius: 0.75rem;
  border: 1px solid var(--border-soft);
  background: var(--surface-input);
  color: var(--text-main);
  padding: 0.75rem 0.9rem;
  font-size: 0.95rem;
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

.answer-check textarea:focus {
  outline: 2px solid var(--focus-ring);
  border-color: transparent;
}

.check-result {
  min-height: 1.4rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.check-result[data-tone="good"] {
  color: var(--good-color);
}

.check-result[data-tone="okay"] {
  color: #38bdf8;
}

.check-result[data-tone="warning"] {
  color: var(--warn-color);
}

.card-actions {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.75rem;
}

.btn {
  padding: 0.7rem 1rem;
  border-radius: 0.8rem;
  border: 1px solid var(--border-soft);
  background: var(--button-bg);
  color: var(--text-main);
  cursor: pointer;
  font-weight: 600;
  transition: border-color 0.2s ease, background 0.2s ease, transform 0.2s ease;
}

.btn:hover {
  border-color: var(--button-border-hover);
  transform: translateY(-1px);
}

.btn.primary {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.3), rgba(37, 99, 235, 0.3));
  border-color: rgba(56, 189, 248, 0.5);
}

.btn.ghost {
  background: transparent;
}

.theme-switcher {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.theme-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
  font-weight: 600;
}

.theme-select {
  background: var(--bg-secondary);
  color: var(--text-main);
  border: 1px solid var(--border-soft);
  border-radius: 0.65rem;
  padding: 0.5rem 0.75rem;
  font-weight: 600;
}

:root[data-theme='light'] .answer-table th {
  color: #1d4ed8;
}

:root[data-theme='light'] code,
:root[data-theme='light'] pre,
:root[data-theme='light'] code[class*="language-"],
:root[data-theme='light'] pre[class*="language-"] {
  color: #1f1f1f;
}

:root[data-theme='light'] .token.keyword {
  color: #0000ff;
}

:root[data-theme='light'] .token.class-name,
:root[data-theme='light'] .token.namespace,
:root[data-theme='light'] .token.builtin {
  color: #267f99;
}

:root[data-theme='light'] .token.string {
  color: #a31515;
}

:root[data-theme='light'] .token.number {
  color: #098658;
}

:root[data-theme='light'] .token.comment {
  color: #008000;
}

:root[data-theme='light'] .token.function {
  color: #795e26;
}

:root[data-theme='light'] .token.property,
:root[data-theme='light'] .token.parameter,
:root[data-theme='light'] .token.variable {
  color: #001080;
}

:root[data-theme='light'] .token.operator,
:root[data-theme='light'] .token.punctuation {
  color: #000000;
}

@media (max-width: 960px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: relative;
    max-height: none;
  }
}

/* Punctuation: {}, (), [], etc. */
.token.punctuation {
  color: #d4d4d4;
}

/* Properties */
.token.property {
  color: #9cdcfe;
}

/* Variables, parameters */
.token.parameter,
.token.variable {
  color: #9cdcfe;
}

/* Attributes like [HttpGet] */
.token.annotation,
.token.attr-name {
  color: #4ec9b0;
}

/* Boolean, null, etc. */
.token.boolean,
.token.constant,
.token.null {
  color: #569cd6;
}

/* Namespaces */
.token.namespace {
  color: #4ec9b0;
}

/* Generics <T> */
.token.generic {
  color: #4ec9b0;
}

.card-meta {
  margin: 0;
  font-size: clamp(0.75rem, 2vw, 0.9rem);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  text-align: left;
}

/* Scrollbar styling for code blocks */
pre::-webkit-scrollbar {
  height: 8px;
}

pre::-webkit-scrollbar-track {
  background: var(--bg-primary);
  border-radius: 4px;
}

pre::-webkit-scrollbar-thumb {
  background: var(--code-border);
  border-radius: 4px;
}

pre::-webkit-scrollbar-thumb:hover {
  background: #475569;
}

@media (max-width: 768px) {
  body {
    padding: 1.5rem 1rem;
  }

  .card-question {
    font-size: 1.5rem;
  }

  .answer-text {
    font-size: 1rem;
  }

  pre {
    padding: 2.5rem 1rem 1rem 1rem;
    font-size: 0.8rem;
  }

  .code-badge {
    font-size: 0.75rem;
    padding: 0.3rem 0.6rem;
  }
}

@media (max-width: 480px) {
  body {
    padding: 1rem 0.75rem;
  }

  .card-type-badge {
    font-size: 0.65rem;
    padding: 0.25rem 0.65rem;
  }

  .card-question {
    font-size: 1.25rem;
  }

  .answer-text {
    font-size: 0.95rem;
  }

  pre {
    font-size: 0.75rem;
  }

  .card-meta {
    letter-spacing: 0.1em;
  }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
  .card-panel,
  * {
    transition-duration: 0.01ms !important;
  }
}

/* Print styles */
@media print {
  body {
    background: white;
    color: black;
  }

  .card-panel,
  .sidebar {
    background: white;
    color: black;
    border-color: #ccc;
  }

  .code-wrapper {
    border: 1px solid #ccc;
    page-break-inside: avoid;
  }

  pre {
    background: #f5f5f5;
  }

  code {
    color: black;
  }
}