/* ============================================================
   Tiny Language Model — Interactive Educational Site
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;600&family=Inter:wght@400;500;600;700&display=swap');

:root {
  --bg-primary: #08090d;
  --bg-secondary: #0f1117;
  --bg-card: #151720;
  --bg-input: #1a1c28;
  --border: #252836;
  --border-hover: #3a3f55;
  --text-primary: #e8e9ed;
  --text-secondary: #8b8fa3;
  --text-muted: #5a5e72;
  --accent: #4f8ff7;
  --accent-glow: rgba(79, 143, 247, 0.15);
  --accent-hover: #6ba3ff;
  --green: #4fc78f;
  --green-glow: rgba(79, 199, 143, 0.15);
  --orange: #f7a84f;
  --pink: #f75f8a;
  --purple: #7c5ff7;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 4px 24px rgba(0,0,0,0.3);
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

/* ---- Layout ---- */

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ---- Header & Nav ---- */

header {
  border-bottom: 1px solid var(--border);
  background: var(--bg-secondary);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
}

.logo {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 600;
  font-size: 18px;
  color: var(--accent);
  letter-spacing: -0.5px;
}

.logo span {
  color: var(--text-muted);
  font-weight: 400;
}

nav {
  display: flex;
  gap: 4px;
}

.nav-tab {
  padding: 8px 20px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  border: 1px solid transparent;
  transition: all 0.2s;
  background: none;
  font-family: inherit;
}

.nav-tab:hover {
  color: var(--text-primary);
  background: var(--bg-card);
}

.nav-tab.active {
  color: var(--accent);
  background: var(--accent-glow);
  border-color: rgba(79, 143, 247, 0.2);
}

/* ---- Pages ---- */

.page {
  display: none;
  padding: 40px 0 80px;
  animation: fadeIn 0.3s ease;
}

.page.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ---- Learn Page ---- */

.hero {
  text-align: center;
  margin-bottom: 56px;
}

.hero h1 {
  font-size: 36px;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

.hero h1 .gradient-text {
  background: linear-gradient(135deg, var(--accent), var(--purple));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  color: var(--text-secondary);
  font-size: 17px;
  max-width: 600px;
  margin: 0 auto;
}

.concept-section {
  margin-bottom: 48px;
}

.concept-section h2 {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.concept-section h2 .step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--accent-glow);
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  font-family: 'IBM Plex Mono', monospace;
  flex-shrink: 0;
}

.concept-section > p {
  color: var(--text-secondary);
  margin-bottom: 20px;
  font-size: 15px;
  max-width: 720px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

/* ---- Interactive Demos ---- */

.demo-label {
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 8px;
}

.demo-text-display {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 18px;
  color: var(--accent);
  margin-bottom: 16px;
}

.demo-arrow {
  text-align: center;
  color: var(--text-muted);
  font-size: 13px;
  padding: 12px 0;
  position: relative;
}

.demo-arrow::before {
  content: '↓';
  display: block;
  font-size: 18px;
  margin-bottom: 4px;
  color: var(--accent);
}

.token-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.token-cell {
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px 12px;
  min-width: 42px;
  transition: border-color 0.2s;
}

.token-cell:hover {
  border-color: var(--accent);
}

.token-char {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 16px;
  color: var(--text-primary);
  font-weight: 600;
}

.token-id {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 10px;
  color: var(--text-muted);
  margin-top: 4px;
}

.token-merged {
  border-color: var(--green);
  background: var(--green-glow);
}

.token-merged .token-char {
  color: var(--green);
}

.merge-summary {
  margin-top: 12px;
  font-size: 13px;
  color: var(--text-secondary);
  font-family: 'IBM Plex Mono', monospace;
}

/* Tokenization viz (Lab page) */

.merge-rules-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.merge-rule {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 6px 12px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
}

.merge-num {
  color: var(--text-muted);
  font-size: 10px;
  min-width: 20px;
}

.merge-pair {
  color: var(--text-secondary);
}

.merge-arrow-sm {
  color: var(--accent);
  font-size: 14px;
}

.merge-result {
  color: var(--green);
  font-weight: 600;
}

.tokenized-text-display {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  max-height: 260px;
  overflow-y: auto;
  line-height: 1.8;
}

.tokenized-text-display::-webkit-scrollbar {
  width: 6px;
}

.tokenized-text-display::-webkit-scrollbar-track {
  background: var(--bg-input);
  border-radius: 3px;
}

.tokenized-text-display::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

.token-pill {
  display: inline-block;
  padding: 2px 5px;
  border-radius: 3px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  cursor: default;
  border: 1px solid transparent;
  transition: border-color 0.15s;
}

.token-pill:hover {
  border-color: var(--accent);
}

.token-single {
  background: rgba(79, 143, 247, 0.08);
  color: var(--text-secondary);
}

.token-multi {
  background: rgba(79, 199, 143, 0.1);
  color: var(--green);
  font-weight: 500;
  border-color: rgba(79, 199, 143, 0.15);
}

/* Prediction demo */

.context-display {
  display: flex;
  gap: 2px;
  margin-bottom: 8px;
}

.ctx-char {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  height: 40px;
  padding: 0 8px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 4px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  font-weight: 500;
}

.ctx-next {
  background: var(--accent-glow);
  border-color: var(--accent);
  color: var(--accent);
  animation: pulse 1.5s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.prob-bars, .pred-bars {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.prob-bar-row, .pred-bar-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.prob-char, .pred-char {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 13px;
  width: 60px;
  text-align: right;
  color: var(--text-primary);
  flex-shrink: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.prob-bar-track, .pred-bar-track {
  flex: 1;
  height: 20px;
  background: var(--bg-input);
  border-radius: 4px;
  overflow: hidden;
}

.prob-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--purple));
  border-radius: 4px;
  transition: width 0.3s ease;
}

.pred-bar-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 4px;
  transition: width 0.15s ease;
}

.pred-correct .pred-bar-fill {
  background: var(--green);
}

.prob-pct, .pred-pct {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  color: var(--text-muted);
  width: 48px;
  text-align: right;
  flex-shrink: 0;
}

.pred-context {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.pred-correct .pred-char {
  color: var(--green);
}

/* ---- Math Blocks ---- */

.math-block {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin: 16px 0;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  color: var(--orange);
  overflow-x: auto;
  line-height: 1.8;
}

.math-block .comment {
  color: var(--text-muted);
}

/* ---- Concept Grid ---- */

.concept-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.concept-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  transition: border-color 0.2s;
}

.concept-card:hover {
  border-color: var(--border-hover);
}

.concept-card h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.concept-card p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.concept-card .card-color {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  display: inline-block;
  margin-right: 6px;
  vertical-align: middle;
}

/* ---- Lab Page ---- */

.lab-step {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
  transition: border-color 0.2s, opacity 0.2s;
}

.lab-step-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 20px;
  cursor: pointer;
  transition: background 0.2s;
  user-select: none;
}

.lab-step-header:hover {
  background: rgba(255, 255, 255, 0.02);
}

.lab-step-header h2 {
  margin: 0;
  font-size: 17px;
  font-weight: 600;
}

.step-indicator {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 600;
  font-family: 'IBM Plex Mono', monospace;
  background: var(--bg-input);
  color: var(--text-muted);
  flex-shrink: 0;
  transition: background 0.2s, color 0.2s;
}

.lab-step-content {
  padding: 0 20px 20px;
}

/* Step states */
.lab-step.collapsed .lab-step-content {
  display: none;
}

.lab-step.locked {
  opacity: 0.35;
}

.lab-step.locked .lab-step-header {
  cursor: default;
  pointer-events: none;
}

.lab-step.completed .step-indicator {
  background: var(--green-glow);
  color: var(--green);
}

.lab-step.completed .lab-step-header {
  cursor: pointer;
}

.lab-step.active {
  border-color: rgba(79, 143, 247, 0.3);
}

.lab-step.active .step-indicator {
  background: var(--accent);
  color: #fff;
}

.lab-section {
  margin-bottom: 32px;
}

.lab-section h2 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
}

.lab-section h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text-secondary);
}

/* Text input area */

.text-input-area {
  position: relative;
}

textarea#training-text {
  width: 100%;
  min-height: 160px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 13px;
  color: var(--text-primary);
  resize: vertical;
  line-height: 1.6;
  transition: border-color 0.2s;
}

textarea#training-text:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

textarea#training-text::placeholder {
  color: var(--text-muted);
}

#text-stats {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 8px;
  font-family: 'IBM Plex Mono', monospace;
}

/* Sample buttons */

.sample-buttons {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.sample-btn {
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-secondary);
  font-size: 13px;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}

.sample-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-glow);
}

/* File upload */

.upload-area {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 12px;
}

.upload-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  border: 1px dashed var(--border);
  background: none;
  color: var(--text-secondary);
  font-size: 13px;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}

.upload-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

input[type="file"] {
  display: none;
}

/* Controls */

.controls-row {
  display: flex;
  gap: 12px;
  margin-bottom: 16px;
  flex-wrap: wrap;
  align-items: flex-end;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.label-unit {
  font-weight: 400;
  font-style: italic;
  font-size: 9px;
  color: var(--text-muted);
}

.control-group label {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.6px;
}

.control-group .slider-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.control-group input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 120px;
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  outline: none;
}

.control-group input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 2px solid var(--bg-primary);
}

.control-group:has(input:disabled) {
  opacity: 0.3;
  pointer-events: none;
}

.slider-val {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12px;
  color: var(--text-secondary);
  min-width: 36px;
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  font-family: inherit;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 0 20px var(--accent-glow);
}

.btn-danger {
  background: rgba(247, 95, 138, 0.1);
  color: var(--pink);
  border: 1px solid rgba(247, 95, 138, 0.2);
}

.btn-danger:hover {
  background: rgba(247, 95, 138, 0.2);
}

.btn-success {
  background: rgba(79, 199, 143, 0.1);
  color: var(--green);
  border: 1px solid rgba(79, 199, 143, 0.2);
}

.btn-success:hover {
  background: rgba(79, 199, 143, 0.2);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  border-color: var(--border-hover);
  color: var(--text-primary);
}

.btn-icon {
  font-size: 12px;
}

.btn-row {
  display: flex;
  gap: 8px;
  margin: 16px 0;
}

/* Model info */

#model-info {
  margin: 12px 0;
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
}

.info-item {
  background: var(--bg-input);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
}

.info-label {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: 4px;
}

.info-value {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  color: var(--text-primary);
  font-weight: 500;
}

/* Training Visualization */

#training-viz {
  display: none;
}

#training-viz.active {
  display: block;
}


.viz-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 16px;
}

@media (max-width: 720px) {
  .viz-grid {
    grid-template-columns: 1fr;
  }
}

.viz-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  overflow: hidden;
  min-width: 0;
}

.viz-panel h4 {
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: 12px;
}

.viz-panel canvas {
  width: 100%;
  display: block;
}

.training-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

#step-counter, #loss-value {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  color: var(--text-secondary);
}

#loss-value {
  color: var(--accent);
  font-weight: 600;
}

/* Generation section */

.gen-input-row {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
}

#prompt-input {
  flex: 1;
  padding: 10px 16px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 14px;
  transition: border-color 0.2s;
}

#prompt-input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

#prompt-input::placeholder {
  color: var(--text-muted);
}

/* Generated text display */

#generation-output {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  min-height: 80px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 15px;
  line-height: 1.7;
  white-space: pre-wrap;
  word-break: break-word;
  margin-bottom: 16px;
}

.gen-seed {
  color: var(--accent);
  font-weight: 600;
}

.gen-char, .gen-token {
  color: var(--text-primary);
  transition: opacity 0.2s;
  border-right: 1px solid rgba(255, 255, 255, 0.15);
}

/* Generation steps */

#generation-steps-viz h4 {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.gen-steps-scroll {
  max-height: 400px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding-right: 8px;
}

.gen-steps-scroll::-webkit-scrollbar {
  width: 6px;
}

.gen-steps-scroll::-webkit-scrollbar-track {
  background: var(--bg-input);
  border-radius: 3px;
}

.gen-steps-scroll::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

.gen-step {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  transition: border-color 0.2s;
}

.gen-step:hover {
  border-color: var(--border-hover);
}

.gen-step-num {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 10px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.gen-step-ctx {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.gen-step-selected {
  color: var(--green);
  font-weight: 600;
}

.gen-step-conf {
  font-size: 11px;
  color: var(--text-muted);
}

.gen-step-probs {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.gen-prob-pill {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 10px;
  background: var(--bg-input);
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.gen-prob-pill.selected {
  background: var(--green-glow);
  color: var(--green);
  border-color: rgba(79, 199, 143, 0.3);
}

/* Mono helper */
.mono {
  font-family: 'IBM Plex Mono', monospace;
}

/* ---- Diagram ---- */

.architecture-diagram {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  padding: 24px 0;
  flex-wrap: wrap;
}

.arch-block {
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-size: 12px;
  font-weight: 600;
  font-family: 'IBM Plex Mono', monospace;
  text-align: center;
  border: 1px solid;
}

.arch-block.input {
  background: rgba(79, 143, 247, 0.1);
  border-color: rgba(79, 143, 247, 0.2);
  color: var(--accent);
}

.arch-block.embed {
  background: rgba(124, 95, 247, 0.1);
  border-color: rgba(124, 95, 247, 0.2);
  color: var(--purple);
}

.arch-block.hidden {
  background: rgba(247, 168, 79, 0.1);
  border-color: rgba(247, 168, 79, 0.2);
  color: var(--orange);
}

.arch-block.output {
  background: rgba(79, 199, 143, 0.1);
  border-color: rgba(79, 199, 143, 0.2);
  color: var(--green);
}

.arch-arrow {
  font-size: 18px;
  color: var(--text-muted);
}

/* ---- Responsive ---- */

@media (max-width: 768px) {
  .container {
    padding: 0 16px;
  }

  .page {
    padding: 24px 0 60px;
  }

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

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

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

  .math-block {
    font-size: 12px;
    padding: 12px 14px;
    line-height: 1.7;
  }

  .merge-rules-grid {
    gap: 4px;
  }

  .merge-rule {
    padding: 5px 8px;
    font-size: 11px;
    gap: 4px;
  }

  .training-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }
}

@media (max-width: 600px) {
  .header-inner {
    flex-direction: column;
    gap: 8px;
    padding: 10px 0;
  }

  .hero {
    margin-bottom: 36px;
  }

  .hero h1 {
    font-size: 24px;
  }

  .hero p {
    font-size: 15px;
  }

  .concept-section {
    margin-bottom: 36px;
  }

  .concept-section h2 {
    font-size: 19px;
  }

  .concept-section > p {
    font-size: 14px;
  }

  .card {
    padding: 16px;
  }

  /* Controls */
  .controls-row {
    flex-direction: column;
  }

  .control-group input[type="range"] {
    width: 100%;
    min-width: 0;
    height: 6px;
  }

  .control-group input[type="range"]::-webkit-slider-thumb {
    width: 22px;
    height: 22px;
  }

  .control-group {
    width: 100%;
  }

  .control-group .slider-row {
    width: 100%;
  }

  /* Buttons — larger touch targets */
  .btn {
    padding: 12px 24px;
    font-size: 15px;
    min-height: 44px;
  }

  .btn-row {
    flex-wrap: wrap;
  }

  .sample-btn {
    padding: 8px 14px;
    font-size: 14px;
    min-height: 40px;
  }

  .nav-tab {
    padding: 8px 16px;
    font-size: 14px;
    min-height: 40px;
  }

  /* Text input */
  textarea#training-text {
    min-height: 120px;
    font-size: 14px;
  }

  /* Generation */
  .gen-input-row {
    flex-direction: column;
  }

  #prompt-input {
    font-size: 16px; /* prevents iOS zoom on focus */
  }

  #generation-output {
    font-size: 14px;
    padding: 16px;
  }

  /* Diagrams */
  .architecture-diagram {
    flex-direction: column;
    gap: 2px;
    padding: 16px 0;
  }

  .arch-arrow {
    transform: rotate(90deg);
  }

  .arch-block {
    width: 100%;
    max-width: 200px;
  }

  /* Token demo */
  .demo-text-display {
    font-size: 16px;
    word-break: break-all;
  }

  .token-cell {
    padding: 6px 8px;
    min-width: 36px;
  }

  .token-char {
    font-size: 14px;
  }

  /* Prediction demo */
  .context-display {
    flex-wrap: wrap;
  }

  .prob-char, .pred-char {
    font-size: 12px;
    width: 50px;
  }

  .prob-pct, .pred-pct {
    font-size: 11px;
    width: 40px;
  }

  /* Generation steps */
  .gen-step {
    padding: 8px 10px;
  }

  .gen-step-ctx {
    font-size: 12px;
    word-break: break-all;
  }

  .gen-prob-pill {
    font-size: 10px;
    padding: 2px 6px;
  }

  /* Tokenization viz */
  .tokenized-text-display {
    padding: 12px;
    max-height: 200px;
  }

  .token-pill {
    font-size: 11px;
    padding: 2px 4px;
  }

  /* Info grid */
  .info-grid {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .info-item {
    padding: 10px 12px;
  }

  .info-value {
    font-size: 13px;
  }

  /* Lab section */
  .lab-section h2 {
    font-size: 17px;
  }

  /* Lab steps */
  .lab-step-header {
    padding: 14px 16px;
  }

  .lab-step-content {
    padding: 0 16px 16px;
  }

  .lab-step-header h2 {
    font-size: 15px;
  }

}

/* Ensure touch targets are at least 44px on touch devices */
@media (pointer: coarse) {
  .btn {
    min-height: 44px;
  }

  .sample-btn {
    min-height: 44px;
    padding: 10px 16px;
  }

  .nav-tab {
    min-height: 44px;
  }

  .upload-btn {
    min-height: 44px;
    padding: 10px 16px;
  }

  .control-group input[type="range"] {
    height: 6px;
  }

  .control-group input[type="range"]::-webkit-slider-thumb {
    width: 24px;
    height: 24px;
  }
}