:root {
  --paper-bg: #FDFBF7;
  --paper-card: #FFFEFD;
  --paper-muted: #F5F2EC;
  --paper-line: #E8E4DC;
  --ink: #2C2A26;
  --ink-muted: #6B665E;
  --accent-yellow: #FFE066;
  --accent-green: #A8E06C;
  --accent-pink: #FF9EB5;
  --accent-blue: #7EC8E3;
  --brand-navy: #2E3A59;

  --subject-math: var(--accent-blue);
  --subject-chinese: var(--accent-green);
  --subject-english: var(--accent-pink);
  --subject-general: var(--accent-yellow);

  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 40px;
  --space-xxl: 64px;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-pill: 999px;

  --shadow-sm: 0 1px 3px rgba(44, 42, 38, 0.06);
  --shadow-md: 0 4px 12px rgba(44, 42, 38, 0.08);
  --shadow-lg: 0 12px 28px rgba(44, 42, 38, 0.12);

  --font-display: "Noto Serif SC", "STSong", "SimSun", "Songti SC", Georgia, serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-hand: "Kaiti SC", "STKaiti", "KaiTi", cursive;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  color: var(--ink);
  line-height: 1.6;
  background-color: var(--paper-bg);
  background-image:
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 31px,
      var(--paper-line) 31px,
      var(--paper-line) 32px
    ),
    radial-gradient(ellipse at 50% 0, rgba(255, 255, 255, 0.9), transparent 60%);
  background-attachment: fixed;
  min-height: 100vh;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.3;
}

a {
  color: var(--brand-navy);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

button {
  font-family: inherit;
}

/* Layout helpers */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.hidden {
  display: none !important;
}

.center-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
}

/* Brand header */
.brand-header {
  background: var(--paper-card);
  border-bottom: 2px dashed var(--paper-line);
  padding: var(--space-lg) 0;
  margin-bottom: var(--space-xl);
  box-shadow: var(--shadow-sm);
}

.brand-header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-md);
}

.brand-title {
  display: inline;
  font-family: var(--font-display);
  font-size: 1.75rem;
  color: var(--brand-navy);
  background-image: linear-gradient(180deg, transparent 62%, var(--accent-yellow) 62%, var(--accent-yellow) 92%, transparent 92%);
  padding: 0 4px;
}

.brand-header p {
  color: var(--ink-muted);
  margin-top: var(--space-xs);
  font-size: 0.95rem;
}

.header-link {
  color: var(--ink-muted);
  font-size: 0.95rem;
  white-space: nowrap;
}

.header-link:hover {
  color: var(--brand-navy);
}

/* Buttons */
.btn,
button,
.tool-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-md);
  border: none;
  border-radius: var(--radius-pill);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  box-shadow: var(--shadow-sm);
}

.btn:hover,
button:hover,
.tool-link:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
  text-decoration: none;
}

.btn:active,
button:active,
.tool-link:active {
  transform: translateY(0);
}

.btn-primary,
button:not(.btn-secondary):not(.btn-danger):not(.btn-ghost):not(.copy-btn):not(.filter-btn),
.tool-link {
  background: var(--accent-yellow);
  color: var(--brand-navy);
}

.btn-primary:hover,
button:not(.btn-secondary):not(.btn-danger):not(.btn-ghost):not(.copy-btn):hover,
.tool-link:hover {
  background: #FFD94D;
}

.btn-secondary {
  background: var(--paper-muted);
  color: var(--ink);
}

.btn-secondary:hover {
  background: var(--paper-line);
}

.btn-danger {
  background: var(--accent-pink);
  color: var(--brand-navy);
}

.btn-danger:hover {
  background: #FF8AA5;
}

.btn-ghost {
  background: transparent;
  color: var(--ink-muted);
  box-shadow: none;
}

.btn-ghost:hover {
  background: var(--paper-muted);
  box-shadow: none;
}

.copy-btn {
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.85rem;
  background: var(--paper-muted);
  color: var(--ink);
}

.copy-btn:hover {
  background: var(--paper-line);
}

/* Cards */
.card,
.tool-card,
.entry-card,
.info-card,
.admin-section {
  background: var(--paper-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--paper-line);
}

.card {
  padding: var(--space-xl);
}

.tool-card {
  padding: var(--space-lg);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.tool-card:hover {
  transform: rotate(-1deg) translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.entry-card {
  width: 90%;
  max-width: 460px;
  padding: var(--space-xxl) var(--space-xl);
  text-align: center;
}

.info-card {
  padding: var(--space-md) var(--space-lg);
  margin-bottom: var(--space-xl);
}

/* Code entry */
.code-entry {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  max-width: 500px;
  margin: 0 auto;
}

.code-entry input {
  flex: 1;
  padding: var(--space-md) var(--space-lg);
  border: 2px solid var(--paper-line);
  border-radius: var(--radius-pill);
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 2px;
  background: var(--paper-card);
  color: var(--ink);
  transition: border-color 0.2s, box-shadow 0.2s;
}

.code-entry input:focus {
  outline: none;
  border-color: var(--accent-yellow);
  box-shadow: 0 0 0 4px rgba(255, 224, 102, 0.25);
}

.code-entry button {
  white-space: nowrap;
}

/* Forms */
.form-row {
  display: flex;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
  align-items: end;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.form-group label {
  font-size: 0.9rem;
  color: var(--ink-muted);
  font-weight: 600;
}

.form-group input,
.form-group select,
.form-group textarea,
.data-item input {
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--paper-line);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  min-width: 160px;
  background: var(--paper-card);
  color: var(--ink);
  transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus,
.data-item input:focus {
  outline: none;
  border-color: var(--accent-yellow);
  box-shadow: 0 0 0 3px rgba(255, 224, 102, 0.2);
}

/* Lock overlay */
.lock-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(253, 251, 247, 0.96);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.lock-content {
  background: var(--paper-card);
  border: 2px dashed var(--paper-line);
  border-radius: var(--radius-lg);
  padding: var(--space-xxl) var(--space-xl);
  max-width: 420px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}

.lock-content h2 {
  margin-bottom: var(--space-sm);
  color: var(--brand-navy);
}

.lock-content p {
  color: var(--ink-muted);
  margin-bottom: var(--space-lg);
}

.lock-content input {
  width: 100%;
  padding: var(--space-md);
  border: 2px solid var(--paper-line);
  border-radius: var(--radius-pill);
  font-size: 1rem;
  margin-bottom: var(--space-md);
  text-transform: uppercase;
  letter-spacing: 2px;
  background: var(--paper-card);
  color: var(--ink);
}

.lock-content input:focus {
  outline: none;
  border-color: var(--accent-yellow);
  box-shadow: 0 0 0 4px rgba(255, 224, 102, 0.25);
}

/* Home page */
.hero {
  text-align: center;
  margin-bottom: var(--space-xxl);
}

.hero h2 {
  font-size: 2rem;
  margin-bottom: var(--space-lg);
  color: var(--brand-navy);
}

.tools-section {
  margin-bottom: var(--space-xxl);
}

.tools-section h2 {
  font-size: 1.6rem;
  margin-bottom: var(--space-sm);
  color: var(--brand-navy);
}

.hint {
  color: var(--ink-muted);
  margin-bottom: var(--space-lg);
}

/* Filter bar */
.filter-bar {
  display: flex;
  gap: 8px;
  margin-bottom: var(--space-lg);
}

.filter-btn {
  padding: 6px 20px;
  border-radius: 999px;
  border: 2px solid #D1CFC9;
  background: #FFFFFF;
  color: var(--ink-muted);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
}

.filter-btn:hover {
  border-color: #C4A520;
  color: var(--ink);
}

.filter-btn.active {
  background: var(--accent-yellow);
  border-color: var(--accent-yellow);
  color: var(--brand-navy);
  font-weight: 700;
  box-shadow: 0 2px 10px rgba(255, 224, 102, 0.5);
}

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.tool-icon {
  font-size: 3rem;
  margin-bottom: var(--space-sm);
}

/* ===== 免费体验区 ===== */
.free-zone {
  margin: var(--space-xl) 0 var(--space-xxl);
}

.free-zone-header {
  text-align: center;
  margin-bottom: var(--space-lg);
}

.free-zone-title {
  font-family: var(--font-display);
  font-size: 1.75rem;
  color: var(--brand-navy);
  margin-bottom: var(--space-xs);
}

.highlight-underline {
  background-image: linear-gradient(180deg, transparent 58%, var(--accent-yellow) 58%, var(--accent-yellow) 90%, transparent 90%);
}

.free-zone-sub {
  color: var(--ink-muted);
  font-size: 0.95rem;
}

.free-tools-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  padding: 12px 0 24px;
}

.free-card {
  position: relative;
  background: var(--paper-card);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(44,42,38,0.06), 0 8px 24px rgba(44,42,38,0.08);
  text-decoration: none;
  transition: transform 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94),
              box-shadow 0.4s ease;
  transform-style: preserve-3d;
  perspective: 1000px;
  animation: cardRise 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94) both;
  animation-delay: calc(var(--i) * 0.1s);
  display: flex;
  flex-direction: column;
}

@keyframes cardRise {
  from {
    opacity: 0;
    transform: translateY(40px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.free-card:hover {
  z-index: 10;
  box-shadow: 0 16px 32px rgba(44,42,38,0.12), 0 32px 64px rgba(44,42,38,0.1);
}

.free-card-media {
  position: relative;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background: var(--paper-muted);
}

.free-card-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: top center;
  transition: transform 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.free-card:hover .free-card-media img {
  transform: scale(1.08);
}

.free-card-glow {
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(255,224,102,0.3) 0%, transparent 70%);
  opacity: 0;
  transition: opacity 0.5s ease;
  pointer-events: none;
  z-index: 2;
}

.free-card:hover .free-card-glow {
  opacity: 1;
}

.free-card-shine {
  position: absolute;
  inset: 0;
  background: linear-gradient(105deg, transparent 40%, rgba(255,255,255,0.08) 45%, rgba(255,255,255,0.25) 50%, rgba(255,255,255,0.08) 55%, transparent 60%);
  transform: translateX(-100%);
  transition: transform 0.8s ease;
  pointer-events: none;
  z-index: 3;
}

.free-card:hover .free-card-shine {
  transform: translateX(100%);
}

.free-card-fallback {
  font-size: 3rem;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.free-card-body {
  padding: 16px;
  display: flex;
  align-items: center;
  gap: 12px;
  position: relative;
  z-index: 4;
  background: var(--paper-card);
}

.free-card-stripe {
  width: 5px;
  height: 40px;
  border-radius: 3px;
  flex-shrink: 0;
  transition: height 0.3s ease;
}

.free-card:hover .free-card-stripe {
  height: 48px;
}

.free-card-text {
  flex: 1;
  min-width: 0;
}

.free-card-text h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--brand-navy);
  margin: 0 0 2px;
  transition: color 0.3s;
}

.free-card-text p {
  font-size: 0.82rem;
  color: var(--ink-muted);
  margin: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.free-card-cta {
  flex-shrink: 0;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--brand-navy);
  opacity: 0;
  transform: translateX(-8px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.free-card:hover .free-card-cta {
  opacity: 1;
  transform: translateX(0);
}

/* Free badge on grid cards */
.free-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  background: var(--accent-yellow);
  color: var(--brand-navy);
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  z-index: 2;
}

/* Preview image */
.tool-preview-wrap {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-md);
  position: relative;
  background: var(--paper-muted);
}

.tool-preview-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: top center;
  transition: object-position 2s ease, transform 0.5s ease;
}

.tool-card:hover .tool-preview-img {
  object-position: center bottom;
  transform: scale(1.03);
}

.tool-icon-fallback {
  font-size: 3rem;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
}

.tool-card h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-xs);
  color: var(--brand-navy);
}

.tool-meta {
  margin-bottom: var(--space-md);
}

.marker-badge {
  display: inline-block;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--brand-navy);
  background: var(--accent-yellow);
}

.marker-badge[data-subject="数学"],
.marker-badge[data-subject="math"] {
  background: var(--subject-math);
}

.marker-badge[data-subject="语文"],
.marker-badge[data-subject="chinese"] {
  background: var(--subject-chinese);
}

.marker-badge[data-subject="英语"],
.marker-badge[data-subject="english"] {
  background: var(--subject-english);
}

.marker-badge[data-subject="通用"],
.marker-badge[data-subject="general"] {
  background: var(--subject-general);
}

.tool-desc {
  color: var(--ink-muted);
  font-size: 0.95rem;
  margin: var(--space-md) 0 var(--space-lg);
  min-height: 48px;
}

.tool-link {
  padding: var(--space-sm) var(--space-md);
  font-size: 0.95rem;
}

/* Footer */
.footer {
  text-align: center;
  padding: var(--space-xl) 0;
  color: var(--ink-muted);
  border-top: 1px solid var(--paper-line);
}

/* Workspace */
.workspace-info {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-lg);
}

.workspace-info .label {
  color: var(--ink-muted);
  font-size: 0.9rem;
}

.workspace-info .value {
  font-weight: 700;
  color: var(--brand-navy);
  font-size: 1.05rem;
}

.loading {
  text-align: center;
  padding: var(--space-xxl);
  color: var(--ink-muted);
  font-size: 1.1rem;
}

.error-box {
  text-align: center;
  padding: var(--space-xxl) var(--space-xl);
  background: var(--paper-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--paper-line);
}

.error-box h2 {
  color: var(--accent-pink);
  margin-bottom: var(--space-sm);
}

.error-box p {
  color: var(--ink-muted);
  margin-bottom: var(--space-lg);
}

.error-msg {
  color: var(--accent-pink);
  margin-top: var(--space-md);
  min-height: 24px;
  font-weight: 600;
}

.success-msg {
  color: #5A8F3A;
  margin-top: var(--space-sm);
  font-weight: 600;
}

/* Tool page */
.tool-page {
  min-height: 100vh;
}

.tool-header {
  background: var(--paper-card);
  padding: var(--space-md) var(--space-lg);
  border-bottom: 2px dashed var(--paper-line);
  box-shadow: var(--shadow-sm);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.tool-header h1 {
  font-size: 1.35rem;
  color: var(--brand-navy);
}

.tool-header .code-info {
  color: var(--ink-muted);
  font-size: 0.9rem;
}

.tool-layout {
  display: flex;
  height: calc(100vh - 70px);
  gap: var(--space-lg);
  padding: var(--space-lg);
}

.tool-sidebar {
  width: 360px;
  min-width: 340px;
  flex-shrink: 0;
  background: var(--paper-card);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  overflow-y: auto;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--paper-line);
}

.tool-sidebar h3 {
  font-size: 1.1rem;
  margin-bottom: var(--space-md);
  color: var(--brand-navy);
}

.tool-main {
  flex: 1;
  min-width: 0;
  background: var(--paper-card);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--paper-line);
  display: flex;
  flex-direction: column;
}

.tool-placeholder {
  padding: var(--space-xxl) var(--space-lg);
  text-align: center;
  color: var(--ink-muted);
}

.tool-placeholder h2 {
  color: var(--brand-navy);
  margin-bottom: var(--space-md);
}

.tool-placeholder .btn {
  margin-top: var(--space-lg);
}

/* Tool data list */
.data-list {
  margin-top: var(--space-md);
}

.data-item {
  display: flex;
  gap: var(--space-xs);
  align-items: center;
  padding: var(--space-xs) var(--space-sm);
  background: var(--paper-muted);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-xs);
}

.data-item input {
  flex: 1;
  min-width: 0;
  padding: 6px var(--space-sm);
  border: 1px solid var(--paper-line);
  border-radius: var(--radius-sm);
  background: var(--paper-card);
  color: var(--ink);
}

.data-item input[type="number"] {
  width: 56px;
  flex: none;
}

.data-item button {
  padding: 4px 8px;
  font-size: 0.8rem;
  white-space: nowrap;
}

.btn-group {
  display: flex;
  gap: var(--space-sm);
  margin-top: var(--space-md);
  flex-wrap: wrap;
}

.btn-group button,
.btn-group label {
  flex: 1;
  min-width: 100px;
}

.btn-group button {
  padding: var(--space-sm);
  font-size: 0.9rem;
}

.file-upload {
  flex: 1;
  min-width: 100px;
}

.file-upload button {
  width: 100%;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.sync-status {
  min-height: 24px;
  margin-top: var(--space-sm);
  font-size: 0.9rem;
  text-align: center;
  color: var(--ink-muted);
}

.sync-status.success { color: #5A8F3A; }
.sync-status.error { color: #C45C6F; }
.sync-status.warn { color: #B8860B; }

.hint-warn {
  background: rgba(255, 224, 102, 0.15);
  border: 1px dashed var(--accent-yellow);
  color: var(--brand-navy);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-md);
  font-size: 0.9rem;
}

/* Chart containers */
.chart-container {
  flex: 1;
  position: relative;
  min-height: 300px;
}

#chart-canvas {
  width: 100%;
  height: 100%;
  border-radius: var(--radius-md);
  background: var(--paper-muted);
}

.stats-bar {
  display: flex;
  gap: var(--space-lg);
  margin-bottom: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
}

.stat-item {
  background: var(--paper-muted);
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--radius-md);
  text-align: center;
  min-width: 100px;
  border: 1px solid var(--paper-line);
}

.stat-item .number {
  font-size: 2rem;
  font-weight: 700;
  color: var(--brand-navy);
}

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

/* Admin */
.admin-header {
  background: var(--brand-navy);
  border-bottom: none;
}

.admin-header .brand-title {
  color: var(--paper-card);
  background-image: linear-gradient(180deg, transparent 62%, rgba(255, 224, 102, 0.4) 62%, rgba(255, 224, 102, 0.4) 92%, transparent 92%);
}

.admin-header .header-link {
  color: rgba(255, 255, 255, 0.8);
}

.admin-nav {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
  flex-wrap: wrap;
}

.admin-nav button {
  background: var(--paper-muted);
  color: var(--ink-muted);
  border-radius: var(--radius-pill);
}

.admin-nav button.active,
.admin-nav button:hover {
  background: var(--accent-yellow);
  color: var(--brand-navy);
}

.admin-section {
  padding: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.admin-section h2 {
  margin-bottom: var(--space-md);
  color: var(--brand-navy);
}

.admin-form-full {
  width: 100%;
  max-width: 600px;
  margin-bottom: var(--space-md);
}

.admin-form-full input {
  width: 100%;
}

.table-wrapper {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

th, td {
  padding: var(--space-md);
  text-align: left;
  border-bottom: 1px solid var(--paper-line);
}

th {
  background: var(--paper-muted);
  font-weight: 700;
  color: var(--ink-muted);
}

.generated-codes {
  background: var(--paper-muted);
  border: 1px dashed var(--paper-line);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin-top: var(--space-md);
  font-family: monospace;
  word-break: break-all;
}

.generated-codes .code-item {
  display: inline-block;
  background: var(--paper-card);
  padding: var(--space-xs) var(--space-sm);
  margin: var(--space-xs);
  border-radius: var(--radius-sm);
  border: 1px solid var(--paper-line);
  cursor: pointer;
  transition: transform 0.1s;
}

.generated-codes .code-item:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

/* Manipulative / math atoms */
.manipulative-block {
  border-radius: var(--radius-sm);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.5),
    0 3px 0 rgba(0, 0, 0, 0.08),
    0 4px 8px rgba(0, 0, 0, 0.08);
  background-image: linear-gradient(180deg, rgba(255,255,255,0.2) 0%, rgba(0,0,0,0.05) 100%);
}

.math-rod {
  border-radius: var(--radius-pill);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.5),
    0 2px 0 rgba(0, 0, 0, 0.08),
    0 3px 6px rgba(0, 0, 0, 0.08);
}

.math-bead {
  border-radius: 50%;
  box-shadow:
    inset 0 -3px 6px rgba(0, 0, 0, 0.1),
    0 2px 4px rgba(0, 0, 0, 0.1);
  background: radial-gradient(circle at 30% 30%, rgba(255,255,255,0.8), transparent 50%);
}

.math-expression {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-body);
  font-size: 1.2rem;
}

.math-expression .operator {
  color: var(--ink-muted);
  font-weight: 700;
}

.math-expression .operand {
  font-weight: 700;
  color: var(--brand-navy);
}

.math-expression .result {
  font-weight: 700;
  color: var(--brand-navy);
  border-bottom: 3px solid var(--accent-yellow);
}

.fraction {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  vertical-align: middle;
  font-size: 1rem;
}

.fraction .top {
  padding: 0 var(--space-xs);
}

.fraction .bar {
  width: 100%;
  height: 2px;
  background: var(--ink);
}

.fraction .bottom {
  padding: 0 var(--space-xs);
}

.step-card {
  background: var(--paper-card);
  border-left: 4px solid var(--accent-yellow);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: var(--space-md) var(--space-lg);
  margin-bottom: var(--space-md);
  box-shadow: var(--shadow-sm);
}

.step-number {
  font-family: var(--font-hand);
  font-size: 1.4rem;
  color: var(--accent-yellow);
  margin-right: var(--space-sm);
  text-shadow: 1px 1px 0 rgba(0,0,0,0.1);
}

/* Responsive */
@media (max-width: 900px) {
  .tool-sidebar {
    width: 100%;
    min-width: 0;
    flex-shrink: 1;
  }

  .tool-layout {
    flex-direction: column;
    height: auto;
  }

  .tool-main {
    min-height: 400px;
  }
}

@media (max-width: 768px) {
  .brand-header .container {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
  }

  .code-entry {
    flex-direction: column;
  }

  .workspace-info {
    flex-direction: column;
    gap: var(--space-sm);
  }

  .tools-grid {
    grid-template-columns: 1fr;
  }

  .stats-bar {
    gap: var(--space-sm);
  }

  .form-row {
    flex-direction: column;
    align-items: stretch;
  }

  .form-group input,
  .form-group select {
    width: 100%;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }

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

  .hero h2 {
    font-size: 1.5rem;
  }

  .card, .entry-card {
    padding: var(--space-lg);
  }
}