:root {
  --sentence-highlight: #fff8b8;   /* light yellow: spoken sentence */
  --word-highlight: #ffd21f;       /* dark yellow: spoken word */
  --accent: #2f6fde;
  --bg: #fafaf7;
  --bar-bg: #ffffff;
  --border: #e2e2da;
  --text: #1d1d1b;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  background: var(--bg);
  color: var(--text);
}

/* ---------- top bar ---------- */
#topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.6rem 1rem;
  background: var(--bar-bg);
  border-bottom: 1px solid var(--border);
  font-family: system-ui, sans-serif;
}

#logo { font-weight: 700; white-space: nowrap; }

#url-input {
  flex: 1;
  min-width: 10rem;
  padding: 0.45rem 0.7rem;
  font-size: 0.95rem;
  border: 1px solid var(--border);
  border-radius: 6px;
}

button, .btn {
  padding: 0.45rem 0.9rem;
  font-size: 0.95rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: #f3f3ee;
  cursor: pointer;
  user-select: none;
}
button:hover, .btn:hover { background: #e9e9e2; }
#load-btn { background: var(--accent); border-color: var(--accent); color: #fff; }
#load-btn:hover { background: #2558b4; }

/* disabled inputs/buttons while a document is processing */
button:disabled, #url-input:disabled { opacity: 0.5; cursor: not-allowed; }
.btn.disabled { opacity: 0.5; pointer-events: none; }

/* cancel (✕) button shown during processing */
#cancel-btn {
  margin-left: auto;
  width: 2rem;
  height: 2rem;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  line-height: 1;
  border-radius: 50%;
  color: #c0392b;
  border-color: #e3b6b0;
}
#cancel-btn:hover { background: #f7e3e0; }
#cancel-btn.hidden { display: none; }

#status {
  font-size: 0.85rem;
  color: #777;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 28ch;
}
#status.error { color: #c0392b; }

/* ---------- article ---------- */
#paper {
  max-width: 46rem;
  margin: 0 auto;
  padding: 1.5rem 1.2rem 9rem;
  line-height: 1.75;
  font-size: 1.06rem;
}

#placeholder { color: #666; margin-top: 4rem; }
#placeholder h2 { color: var(--text); }
kbd {
  font-family: system-ui, sans-serif;
  font-size: 0.8em;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 0 0.35em;
  background: #fff;
}
.demo-sent { background: var(--sentence-highlight); border-radius: 3px; }
.demo-word { background: var(--word-highlight); border-radius: 3px; }

#paper h1.doc-title { font-size: 1.7rem; line-height: 1.3; }
#paper .doc-source { font-family: system-ui, sans-serif; font-size: 0.8rem; color: #888; margin-bottom: 2rem; }
#paper .doc-source a { color: var(--accent); }
#paper h2, #paper h3, #paper h4 { line-height: 1.35; margin-top: 1.8em; }

#paper figure {
  margin: 1.6rem 0;
  text-align: center;
}
#paper figure img {
  max-width: 100%;
  max-height: 26rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: #fff;
}
#paper figcaption {
  font-size: 0.92rem;
  color: #555;
  margin-top: 0.5rem;
  text-align: left;
}

/* ---------- sentence / word highlighting ---------- */
.sent {
  cursor: pointer;
  border-radius: 3px;
  transition: background 0.15s ease;
}
.sent:hover { background: #f0f0e4; }
.sent.active {
  background: var(--sentence-highlight);
  box-decoration-break: clone;
  -webkit-box-decoration-break: clone;
}
.sent .w { border-radius: 3px; }
.sent .w .katex { font-size: 1em; }
/* Long standalone equations: centered block, horizontally scrollable */
.sent .w.math-block {
  display: block;
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  text-align: center;
  padding: 0.5em 0;
  margin: 0.2em 0;
}
.sent .w.active {
  background: var(--word-highlight);
  box-decoration-break: clone;
  -webkit-box-decoration-break: clone;
}
.sent.loading { opacity: 0.55; }

/* ---------- bottom control bar ---------- */
#controls {
  position: fixed;
  bottom: 1.2rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.55rem 0.9rem;
  background: var(--bar-bg);
  border: 1px solid var(--border);
  border-radius: 999px;
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.12);
  font-family: system-ui, sans-serif;
}
#controls.hidden { display: none; }

#controls button {
  width: 2.7rem;
  height: 2.7rem;
  padding: 0;
  font-size: 1.05rem;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}
#play-btn {
  width: 3.3rem;
  height: 3.3rem;
  font-size: 1.3rem;
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
#play-btn:hover { background: #2558b4; }
#play-btn.busy { opacity: 0.6; }

#speed-select {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.3rem 0.4rem;
  background: #f3f3ee;
}
#progress { font-size: 0.8rem; color: #888; min-width: 7ch; text-align: right; }