````markdown
## Design System — "Speak Clearly" Theme

### CSS Reset

All elements: `box-sizing: border-box; margin: 0; padding: 0`

---

### Root Variables
```css
--bg-deep: #0f1117
--bg-surface: #181b24
--bg-elevated: #1f2330
--bg-card: #252a36
--bg-hover: #2c3242

--text-primary: #d8dae0
--text-secondary: #9ca0ad
--text-muted: #8b90a5
--text-bright: #eef0f5

--accent: #6ea8d7
--accent-a18: #6ea8d72e
--accent-a30: #6ea8d74d
--accent-a40: #6ea8d766
--accent-warm: #d4a06a
--accent-green: #7bc89c
--accent-rose: #c98a9a
--accent-rose-a08: #c98a9a14

--evidence-strong: #7bc89c
--evidence-strong-a18: #7bc89c2e
--evidence-strong-a30: #7bc89c4d
--evidence-moderate: #d4a06a
--evidence-moderate-a18: #d4a06a2e
--evidence-moderate-a30: #d4a06a4d
--evidence-emerging: #c98a9a
--evidence-emerging-a18: #c98a9a2e
--evidence-emerging-a30: #c98a9a4d

--border: #2a2f3d
--border-light: #353b4d

--font-display: 'Newsreader', 'Georgia', serif
--font-body: 'DM Sans', 'Noto Sans KR', sans-serif
--font-mono: 'JetBrains Mono', monospace

--measure: 72ch
--space-xs:  0.25rem
--space-s:   0.5rem
--space-m:   1rem
--space-l:   1.5rem
--space-xl:  2.5rem
--space-2xl: 4rem

--radius: 6px
--radius-lg: 10px
```

---

### Google Fonts Import
````
Newsreader: ital,opsz,wght@0,6..72,400;0,6..72,500;0,6..72,600;1,6..72,400
DM Sans: ital,opsz,wght@0,9..40,400;0,9..40,500;0,9..40,600;1,9..40,400
Noto Sans KR: wght@400;500;700
JetBrains Mono: wght@400
display=swap
````

---

### HTML / Body
```css
html {
  font-size: 17px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 1.7;
  color: var(--text-primary);
  background: var(--bg-deep);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
```

---

### Typography

#### Headings

All headings: `font-family: --font-display`, `font-weight: 500`, `line-height: 1.25`, `color: --text-bright`, `letter-spacing: -0.01em`

| Element | Size | Weight | Letter-spacing | Other |
|---|---|---|---|---|
| h1 | 2.6rem | 400 | -0.02em | — |
| h2 | 1.65rem | 500 | -0.01em | `margin-top: 4rem`, `margin-bottom: 1.5rem`, `padding-bottom: 0.5rem`, `border-bottom: 1px solid --border` |
| h3 | 1.25rem | 500 | -0.01em | `margin-top: 2.5rem`, `margin-bottom: 1rem`, `color: --accent` |
| h4 | 1.05rem | 500 | -0.01em | `margin-top: 1.5rem`, `margin-bottom: 0.5rem` |

#### Body & Inline
```css
p {
  margin-bottom: 1rem;
  max-width: 72ch;
}

a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-color: var(--accent-a40);
  text-underline-offset: 2px;
  transition: text-decoration-color 0.2s;
}
a:hover { text-decoration-color: var(--accent); }
a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}

strong {
  font-weight: 600;
  color: var(--text-bright);
}

em { font-style: italic; } /* explicit override needed for DM Sans */

code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--bg-elevated);
  padding: 0.15em 0.4em;
  border-radius: 3px;
}

blockquote {
  border-left: 3px solid var(--accent);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  background: var(--bg-surface);
  border-radius: 0 6px 6px 0;
  font-style: italic;
  color: var(--text-secondary);
}
blockquote p { margin-bottom: 0; }
```

#### Utility Classes
```css
.muted  { color: var(--text-muted); }
.small  { font-size: 0.88rem; }
.text-center { text-align: center; }

/* IPA / phonetic notation */
.ipa {
  font-family: var(--font-mono);
  font-size: 0.92em;
}

/* Kicker / overline label */
.kicker {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  display: block;
  margin-bottom: 1rem;
}
```

---

### Layout
```css
.page-wrapper {
  max-width: 900px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem;
}

hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 4rem 0;
}
```

**Mobile (`max-width: 600px`):**
- `html { font-size: 16px }`
- `.page-wrapper { padding: 1.5rem 1rem }`
- `h1 { font-size: 2rem }`

---

### Header Block
```css
header {
  text-align: center;
  padding: 4rem 0;
  margin-bottom: 2.5rem;
  border-bottom: 1px solid var(--border);
}
/* Structure: .kicker → h1 → .subtitle */
header .subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 55ch;
  margin: 0 auto;
  line-height: 1.6;
}
```

---

### Feature / Quickstart Banner
```css
.quickstart {
  background: linear-gradient(135deg, var(--bg-elevated), var(--bg-card));
  border: 1px solid var(--accent-a30);
  border-radius: var(--radius-lg);
  padding: 1.5rem 2.5rem;
  margin-bottom: 4rem;
  position: relative;
  overflow: hidden;
}
/* Decorative top line */
.quickstart::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}
```

---

### Status / Evidence Badge
```css
.evidence-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35em;
  font-size: 0.72rem;
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.2em 0.6em;
  border-radius: 20px;       /* pill */
  vertical-align: middle;
  font-weight: 500;
}
/* Dot via ::before */
.evidence-tag::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
}

.evidence-strong  { background: #7bc89c2e; color: #7bc89c; border: 1px solid #7bc89c4d; }
.evidence-strong::before  { background: #7bc89c; }

.evidence-moderate  { background: #d4a06a2e; color: #d4a06a; border: 1px solid #d4a06a4d; }
.evidence-moderate::before  { background: #d4a06a; }

.evidence-emerging  { background: #c98a9a2e; color: #c98a9a; border: 1px solid #c98a9a4d; }
.evidence-emerging::before  { background: #c98a9a; }
```

Reuse this pattern for any confidence, status, tier, or category badge system.

---

### Time / Meta Inline Badge
```css
.time-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  background: var(--accent-a18);
  color: var(--accent);
  padding: 0.2em 0.6em;
  border-radius: 4px;
  margin-right: 0.5rem;
}
```

---

### Collapsible (`<details>` / `<summary>`)
```css
details {
  margin: 1rem 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
details[open] { border-color: var(--border-light); }

summary {
  padding: 1rem 1.5rem;
  background: var(--bg-surface);
  cursor: pointer;
  font-weight: 500;
  color: var(--text-bright);
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  user-select: none;
  transition: background 0.15s;
}
summary:hover { background: var(--bg-elevated); }
summary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;   /* inset — differs from default 2px outset */
}
summary::-webkit-details-marker { display: none; }

/* Rotating arrow */
summary::before {
  content: '▸';
  font-size: 0.85em;
  color: var(--accent);
  transition: transform 0.2s;
  flex-shrink: 0;
  speak: never;
}
details[open] > summary::before { transform: rotate(90deg); }

.details-body {
  padding: 1.5rem;
  background: var(--bg-deep);
}
```

---

### Cards

#### Exercise Card
```css
.exercise-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin: 1.5rem 0;
}
.exercise-card h4 {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-top: 0;
}
```

#### Routine / Feature Box
```css
.routine-box {
  background: linear-gradient(135deg, var(--bg-card), var(--bg-elevated));
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 1.5rem 2.5rem;
  margin: 1.5rem 0;
}
```

#### Numbered Steps List
```css
.exercise-steps {
  list-style: none;
  counter-reset: step;
  padding-left: 0;
}
.exercise-steps li {
  counter-increment: step;
  padding: 0.5rem 0 0.5rem 2.2em;
  position: relative;
  max-width: 72ch;
}
.exercise-steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  width: 1.6em;
  height: 1.6em;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: 50%;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent);
  font-family: var(--font-mono);
}
```

---

### Callout / Principle Boxes
```css
/* Warm highlight — key insights, principles */
.principle {
  border-left: 3px solid var(--accent-warm);
  background: var(--bg-surface);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  border-radius: 0 var(--radius) var(--radius) 0;
}
.principle strong { color: var(--accent-warm); }

/* Rose highlight — warnings, cautions */
.warning-box {
  border-left: 3px solid var(--accent-rose);
  background: var(--accent-rose-a08); /* #c98a9a14 */
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  border-radius: 0 var(--radius) var(--radius) 0;
}
```

Both use `role="note"` for accessibility.

---

### Language / Section Aside
```css
.lang-section {
  border-left: 2px solid var(--accent-a40);
  padding-left: 1.5rem;
  margin: 1.5rem 0;
}
.lang-label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}
```

---

### Table of Contents
```css
.toc a { text-decoration: none; }
.toc a:hover { text-decoration: underline; }
.toc ol { padding-left: 1.4em; }
.toc li { margin-bottom: 0.25rem; }
```

---

### References / Bibliography
```css
.references {
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-secondary);
}
/* Hanging indent for each entry */
.references p {
  margin-bottom: 0.5rem;
  padding-left: 2em;
  text-indent: -2em;
}
```

---

### Skip Link (Accessibility)
```css
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  background: var(--accent);
  color: var(--bg-deep);
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  font-weight: 600;
  z-index: 100;
  text-decoration: none;
}
.skip-link:focus { top: 1rem; }
```

---

### Focus Style (Global)
```css
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 2px;
}
/* Exception — summary uses outline-offset: -2px (inset) */
```

---

### Motion
```css
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}
```

Transitions in use:
- Link underline colour: `0.2s`
- Summary background: `0.15s`
- Summary arrow rotation: `0.2s`

---

### Print
```css
@media print {
  body { background: white; color: #222; }
  details { border: 1px solid #ccc; }
  summary { background: #f5f5f5; }
  .details-body { background: white; }
  .evidence-tag { border: 1px solid #666; color: #333; background: #eee; }
  .evidence-tag::before { background: #666; }
  .skip-link { display: none; }
}
```

---

### Footer

No dedicated class. Uses `.text-center .small .muted` utility classes with inline `padding: 2.5rem 0`. Contains a disclaimer paragraph and a "Last updated" line.
````