/* ═══════════════════════════════════════════════
   TOKENS
═══════════════════════════════════════════════ */
:root {
  --bg:             #F7F4EF;
  --surface:        #FFFFFF;
  --surface2:       #F0ECE5;
  --border:         #1A1A1A;
  --border-light:   #D8D3CB;
  --text:           #1A1A1A;
  --text-secondary: #5A5550;
  --text-muted:     #9B9690;
  --accent:         #D4380D;
  --accent-bg:      #FFF3EE;
  --code-bg:        #EDE9E2;
  --output-bg:      #F0ECE5;
  --shadow:         4px 4px 0px #1A1A1A;
  --shadow-sm:      2px 2px 0px #1A1A1A;
}

[data-theme="dark"] {
  --bg:             #111110;
  --surface:        #1C1C1A;
  --surface2:       #252522;
  --border:         #444440;
  --border-light:   #333330;
  --text:           #F0EDE8;
  --text-secondary: #9B9690;
  --text-muted:     #666660;
  --accent:         #FF6B3D;
  --accent-bg:      #2A1A14;
  --code-bg:        #252522;
  --output-bg:      #252522;
  --shadow:         4px 4px 0px #444440;
  --shadow-sm:      2px 2px 0px #444440;
}

/* ═══════════════════════════════════════════════
   EXERCISE 3 — DARK MODE (body class overrides)
   These override the CSS variables so every
   panel updates. The top toggle clears them.
═══════════════════════════════════════════════ */
body.darkMode {
  --bg:             #111111 !important;
  --surface:        #1a1a1a !important;
  --surface2:       #222222 !important;
  --border:         #444444 !important;
  --border-light:   #333333 !important;
  --text:           #eeeeee !important;
  --text-secondary: #aaaaaa !important;
  --text-muted:     #666666 !important;
  --code-bg:        #222222 !important;
  --output-bg:      #222222 !important;
}

body.darkRedMode {
  --bg:             #1a0000 !important;
  --surface:        #220000 !important;
  --surface2:       #2a0000 !important;
  --border:         #660000 !important;
  --border-light:   #440000 !important;
  --text:           #ffcccc !important;
  --text-secondary: #ff9999 !important;
  --text-muted:     #cc6666 !important;
  --accent:         #ff4444 !important;
  --accent-bg:      #330000 !important;
  --code-bg:        #2a0000 !important;
  --output-bg:      #2a0000 !important;
}

/* ═══════════════════════════════════════════════
   RESET & BASE
═══════════════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'DM Sans', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background .25s, color .25s;
}

code {
  font-family: 'DM Mono', monospace;
  font-size: .85em;
  background: var(--code-bg);
  padding: 1px 6px;
  border-radius: 3px;
  border: 1px solid var(--border-light);
}

.hidden { display: none !important; }

/* ═══════════════════════════════════════════════
   TOP BAR
═══════════════════════════════════════════════ */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  height: 56px;
  border-bottom: 2px solid var(--border);
  background: var(--surface);
  position: sticky;
  top: 0;
  z-index: 100;
}

.topbar-left {
  display: flex;
  align-items: center;
  gap: 20px;
}

.topbar-logo {
  font-family: 'Playfair Display', serif;
  font-size: 1.15rem;
  font-weight: 900;
  letter-spacing: -.02em;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
}

.logo-pill {
  background: var(--accent);
  color: #fff;
  font-family: 'DM Mono', monospace;
  font-size: .65rem;
  font-weight: 500;
  padding: 3px 8px;
  border-radius: 2px;
  letter-spacing: .08em;
}

.topbar-divider {
  width: 1px;
  height: 20px;
  background: var(--border-light);
}

.topbar-meta { display: flex; gap: 16px; }

.meta-item {
  font-size: .72rem;
  font-family: 'DM Mono', monospace;
  color: var(--text-secondary);
  letter-spacing: .03em;
}

.meta-item strong { color: var(--text); font-weight: 500; }

.topbar-right { display: flex; align-items: center; gap: 12px; }

.badge {
  font-family: 'DM Mono', monospace;
  font-size: .68rem;
  font-weight: 500;
  padding: 4px 10px;
  border: 1.5px solid var(--border);
  border-radius: 2px;
  letter-spacing: .05em;
  color: var(--text-secondary);
  text-transform: uppercase;
}

.dm-toggle {
  display: flex;
  align-items: center;
  gap: 7px;
  cursor: pointer;
  padding: 5px 10px;
  border: 1.5px solid var(--border-light);
  border-radius: 2px;
  background: transparent;
  color: var(--text);
  font-family: 'DM Mono', monospace;
  font-size: .68rem;
  letter-spacing: .04em;
  transition: border-color .2s, background .2s;
}
.dm-toggle:hover { border-color: var(--border); background: var(--surface2); }

.dm-icon { font-size: .9rem; transition: transform .3s; }
[data-theme="dark"] .dm-icon { transform: rotate(180deg); }

/* ═══════════════════════════════════════════════
   EXERCISE NAV STRIP
═══════════════════════════════════════════════ */
.ex-nav {
  display: flex;
  align-items: stretch;
  border-bottom: 2px solid var(--border);
  background: var(--surface);
  padding: 0 32px;
  gap: 4px;
  overflow-x: auto;
}

.ex-btn {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 22px;
  background: transparent;
  border: none;
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  font-family: 'DM Sans', sans-serif;
  font-size: .82rem;
  font-weight: 600;
  color: var(--text-secondary);
  letter-spacing: .01em;
  transition: color .15s, border-color .15s;
  white-space: nowrap;
}
.ex-btn:hover { color: var(--text); }
.ex-btn.active { color: var(--accent); border-bottom-color: var(--accent); }

.ex-btn-num {
  font-family: 'DM Mono', monospace;
  font-size: .65rem;
  font-weight: 500;
  background: var(--surface2);
  border: 1.5px solid var(--border-light);
  color: var(--text-muted);
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 2px;
  transition: background .15s, color .15s;
}
.ex-btn.active .ex-btn-num {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

/* ═══════════════════════════════════════════════
   MAIN LAYOUT
═══════════════════════════════════════════════ */
.layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  flex: 1;
  min-height: 0;
}

/* ═══════════════════════════════════════════════
   ACTIVITY PANEL (left col)
═══════════════════════════════════════════════ */
.act-panel {
  border-right: 2px solid var(--border);
  background: var(--surface);
  padding: 24px 0;
  position: sticky;
  top: 112px;
  height: calc(100vh - 112px);
  overflow-y: auto;
}

.act-panel-label {
  font-family: 'DM Mono', monospace;
  font-size: .63rem;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: .1em;
  text-transform: uppercase;
  padding: 0 20px 12px;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 8px;
}

.act-group { display: none; }
.act-group.visible { display: block; }

.act-btn {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 20px;
  background: transparent;
  border: none;
  cursor: pointer;
  text-align: left;
  font-family: 'DM Sans', sans-serif;
  font-size: .8rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: background .12s, color .12s;
}
.act-btn:hover { background: var(--surface2); color: var(--text); }
.act-btn.active { background: var(--accent-bg); color: var(--accent); }

.act-btn-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--border-light);
  flex-shrink: 0;
  transition: background .12s;
}
.act-btn.active .act-btn-dot { background: var(--accent); }

.act-panel-empty {
  padding: 32px 20px;
  font-size: .78rem;
  color: var(--text-muted);
  line-height: 1.7;
  font-family: 'DM Mono', monospace;
}

/* ═══════════════════════════════════════════════
   CONTENT AREA (right col)
═══════════════════════════════════════════════ */
.content-area {
  padding: 40px 48px;
  overflow-y: auto;
  max-width: 860px;
}

/* Empty state */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  text-align: center;
  gap: 16px;
}

.empty-mark {
  width: 80px;
  height: 80px;
  border: 2px solid var(--border-light);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  color: var(--text-muted);
}

.empty-state h3 {
  font-family: 'Playfair Display', serif;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text);
}

.empty-state p {
  font-size: .82rem;
  color: var(--text-muted);
  max-width: 260px;
  line-height: 1.7;
}

/* ═══════════════════════════════════════════════
   ACTIVITY CARD
═══════════════════════════════════════════════ */
.activity-card { animation: fadeUp .25s ease; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}

.card-eyebrow {
  font-family: 'DM Mono', monospace;
  font-size: .65rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: .1em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

.activity-card h2 {
  font-family: 'Playfair Display', serif;
  font-size: 1.75rem;
  font-weight: 900;
  line-height: 1.2;
  margin-bottom: 10px;
  color: var(--text);
}

.activity-card .objective {
  font-size: .85rem;
  color: var(--text-secondary);
  line-height: 1.7;
  padding: 12px 16px;
  border-left: 3px solid var(--accent);
  background: var(--accent-bg);
  border-radius: 0 4px 4px 0;
  margin-bottom: 28px;
}

.activity-card h4 {
  font-family: 'DM Mono', monospace;
  font-size: .72rem;
  font-weight: 500;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 20px 0 8px;
}

.activity-card ol,
.activity-card ul {
  padding-left: 20px;
  font-size: .85rem;
  color: var(--text-secondary);
  line-height: 2;
}

/* ═══════════════════════════════════════════════
   DEMO AREA
═══════════════════════════════════════════════ */
.demo-area {
  margin-top: 28px;
  border: 2px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.demo-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: var(--border);
}

.demo-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: rgba(255,255,255,.25);
}

.demo-label {
  font-family: 'DM Mono', monospace;
  font-size: .63rem;
  color: rgba(255,255,255,.6);
  letter-spacing: .08em;
  text-transform: uppercase;
  margin-left: 4px;
}

.demo-body {
  padding: 20px;
  background: var(--surface);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: flex-start;
}

/* Buttons */
.demo-btn {
  font-family: 'DM Mono', monospace;
  font-size: .75rem;
  font-weight: 500;
  padding: 8px 16px;
  background: var(--text);
  color: var(--bg);
  border: 2px solid var(--border);
  border-radius: 3px;
  cursor: pointer;
  letter-spacing: .03em;
  transition: transform .1s, box-shadow .1s;
  box-shadow: var(--shadow-sm);
}
.demo-btn:hover  { transform: translate(-1px,-1px); box-shadow: 3px 3px 0 var(--border); }
.demo-btn:active { transform: translate(1px,1px);  box-shadow: 1px 1px 0 var(--border); }
.demo-btn.outline { background: transparent; color: var(--text); }

/* Inputs */
.demo-input {
  font-family: 'DM Mono', monospace;
  font-size: .78rem;
  padding: 8px 12px;
  background: var(--bg);
  color: var(--text);
  border: 1.5px solid var(--border-light);
  border-radius: 3px;
  outline: none;
  transition: border-color .15s;
  min-width: 160px;
}
.demo-input:focus { border-color: var(--accent); }

.demo-checkbox-label {
  font-size: .82rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
}

/* Output text */
.output-text {
  width: 100%;
  font-family: 'DM Mono', monospace;
  font-size: .75rem;
  line-height: 1.8;
  white-space: pre-wrap;
  color: var(--text);
  background: var(--output-bg);
  padding: 12px 14px;
  border: 1px solid var(--border-light);
  border-radius: 3px;
  margin-top: 4px;
}

/* ═══════════════════════════════════════════════
   EXERCISE 3 SPECIFIC
═══════════════════════════════════════════════ */
#myList {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 8px;
  width: 100%;
}
#myList li {
  font-family: 'DM Mono', monospace;
  font-size: .78rem;
  padding: 8px 12px;
  background: var(--surface2);
  border: 1px solid var(--border-light);
  border-radius: 3px;
  color: var(--text-secondary);
}

#taskList {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 8px;
  width: 100%;
}
#taskList li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: 'DM Mono', monospace;
  font-size: .78rem;
  padding: 8px 12px;
  background: var(--surface2);
  border: 1px solid var(--border-light);
  border-radius: 3px;
  color: var(--text);
}

/* ═══════════════════════════════════════════════
   EXERCISE 4 SPECIFIC
═══════════════════════════════════════════════ */
.score-section-label {
  font-family: 'DM Mono', monospace;
  font-size: .65rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 20px 0 8px;
}

.score-container {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 4px;
}

.score-container input {
  font-family: 'DM Mono', monospace;
  font-size: .78rem;
  padding: 7px 10px;
  width: 110px;
  background: var(--bg);
  color: var(--text);
  border: 1.5px solid var(--border-light);
  border-radius: 3px;
  outline: none;
}
.score-container input:focus { border-color: var(--accent); }

.grade-result {
  margin-top: 20px;
  padding: 16px 20px;
  background: var(--surface2);
  border: 2px solid var(--border);
  border-radius: 4px;
  box-shadow: var(--shadow-sm);
}

.grade-result .final-val {
  font-family: 'Playfair Display', serif;
  font-size: 2.2rem;
  font-weight: 900;
  color: var(--accent);
}

.grade-result .letter {
  font-family: 'DM Mono', monospace;
  font-size: .75rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* ═══════════════════════════════════════════════
   FOOTER
═══════════════════════════════════════════════ */
.footer {
  border-top: 2px solid var(--border);
  background: var(--surface);
  padding: 14px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-left,
.footer-right {
  font-family: 'DM Mono', monospace;
  font-size: .68rem;
  color: var(--text-muted);
  letter-spacing: .05em;
}