/* Study assistant — Focus-mode chat UI */

.study-ai,
#hwStudyAi {
  --sa-bg: var(--paper, #fff);
  --sa-ink: var(--ink, #1a2332);
  --sa-mute: var(--mute, #64748b);
  --sa-line: var(--line, rgba(26, 35, 50, 0.1));
  --sa-line-strong: var(--line-strong, rgba(26, 35, 50, 0.16));
  --sa-soft: var(--bg-deep, #ebeef2);
  --sa-accent: var(--accent, #2563eb);
  --sa-accent-dark: var(--accent-dark, #1d4ed8);
  --sa-accent-soft: var(--accent-soft, #e8eefb);
  --sa-user: color-mix(in srgb, var(--sa-accent) 12%, var(--sa-bg));
  --sa-bot: var(--sa-soft);
  --sa-radius: 14px;
  --sa-ease: cubic-bezier(0.22, 0.8, 0.2, 1);
  --sa-ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  /* Frame height — JS refines this; CSS fallback keeps composer visible */
  --sa-chat-h: min(520px, calc(100dvh - 180px));
  --sa-scroll-thumb-a: color-mix(in srgb, var(--sa-accent) 75%, #fff);
  --sa-scroll-thumb-b: var(--sa-accent-dark);
}

#hwStudyAi.hidden,
.study-ai.hidden {
  display: none !important;
}

#hwStudyAi {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
  box-sizing: border-box;
  width: 100%;
  height: var(--sa-chat-h);
  max-height: var(--sa-chat-h);
  min-height: 320px;
  overflow: visible;
  animation: portalPaneIn 460ms var(--ease-out, var(--sa-ease-out)) both;
}

.hw-panel-body.is-study-ai,
.hw-workspace-body.is-study-ai {
  max-height: none;
  min-height: 0;
  mask-image: none;
  overflow: visible;
  display: flex;
  flex-direction: column;
}

.hw-panel.is-study-ai-tool {
  min-height: 0 !important;
  max-height: none !important;
  height: auto !important;
  overflow: visible;
}

.hw-panel.is-study-ai-tool .hw-panel-body.is-study-ai {
  overflow: visible !important;
  flex: 1 1 auto;
  min-height: 0;
}

.hw-shell.is-study-ai-tool {
  min-height: 0;
}

.hw-panel-body.is-study-ai #hwStudyAi,
.hw-workspace-body.is-study-ai #hwStudyAi {
  flex: 0 0 auto;
  width: 100%;
  min-height: 320px;
  height: var(--sa-chat-h);
  max-height: var(--sa-chat-h);
}

.study-ai__toolbar,
.study-ai__saved {
  flex: 0 0 auto;
}

.study-ai__composer {
  flex: 0 0 auto;
}

/* Toolbar */
.study-ai__toolbar {
  display: flex;
  gap: 12px;
  align-items: center;
  justify-content: space-between;
}

.study-ai__toolbar-text {
  min-width: 0;
}

.study-ai__hint {
  margin: 0;
  color: var(--sa-mute);
  font-size: 0.88rem;
  font-weight: 500;
}

.study-ai__subhint {
  margin: 3px 0 0;
  color: color-mix(in srgb, var(--sa-accent-dark) 55%, var(--sa-mute));
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.01em;
}

.study-ai__ghost {
  min-height: 34px;
  padding: 0 12px;
  border: 1px solid var(--sa-line);
  border-radius: 10px;
  color: var(--sa-ink);
  background: var(--sa-bg);
  font-size: 0.78rem;
  font-weight: 700;
  transition:
    border-color 200ms var(--sa-ease),
    background-color 200ms var(--sa-ease),
    transform 180ms var(--sa-ease-out);
}

.study-ai__ghost:hover {
  border-color: var(--sa-line-strong);
  background: var(--sa-soft);
}

.study-ai__ghost:active {
  transform: scale(0.97);
}

/* Stage — only the message list scrolls */
.study-ai__stage {
  position: relative;
  flex: 1 1 auto;
  min-height: 160px;
  overflow-x: hidden;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  scroll-behavior: smooth;
  scroll-padding-block: 12px;
  border: 1px solid color-mix(in srgb, var(--sa-accent) 14%, var(--sa-line));
  border-radius: var(--sa-radius);
  background:
    radial-gradient(120% 80% at 0% 0%, color-mix(in srgb, var(--sa-accent) 7%, transparent), transparent 55%),
    color-mix(in srgb, var(--sa-bg) 88%, var(--sa-soft));
  box-shadow: inset 0 1px 0 color-mix(in srgb, #fff 40%, transparent);
  scrollbar-width: thin;
  scrollbar-color: var(--sa-scroll-thumb-a) color-mix(in srgb, var(--sa-accent) 8%, transparent);
}

/* Animated custom scrollbar */
.study-ai__stage::-webkit-scrollbar {
  width: 11px;
  display: block;
}

.study-ai__stage::-webkit-scrollbar-track {
  margin: 6px 0;
  background:
    linear-gradient(
      180deg,
      color-mix(in srgb, var(--sa-accent) 6%, transparent),
      color-mix(in srgb, var(--sa-accent) 12%, transparent)
    );
  border-radius: 999px;
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--sa-accent) 10%, transparent);
}

.study-ai__stage::-webkit-scrollbar-thumb {
  border: 2px solid transparent;
  border-radius: 999px;
  background:
    linear-gradient(
      180deg,
      var(--sa-scroll-thumb-a),
      var(--sa-accent),
      var(--sa-scroll-thumb-b),
      var(--sa-accent),
      var(--sa-scroll-thumb-a)
    );
  background-size: 100% 220%;
  background-clip: padding-box;
  box-shadow:
    0 0 10px color-mix(in srgb, var(--sa-accent) 45%, transparent),
    0 0 2px color-mix(in srgb, var(--sa-accent) 70%, transparent);
  animation: studyAiScrollPulse 2.4s linear infinite;
}

.study-ai__stage::-webkit-scrollbar-thumb:hover {
  background:
    linear-gradient(
      180deg,
      #fff,
      var(--sa-scroll-thumb-a),
      var(--sa-accent),
      var(--sa-scroll-thumb-a),
      #fff
    );
  background-size: 100% 220%;
  background-clip: padding-box;
  box-shadow:
    0 0 16px color-mix(in srgb, var(--sa-accent) 60%, transparent),
    0 0 4px color-mix(in srgb, var(--sa-accent) 80%, transparent);
  animation-duration: 1.2s;
}

.study-ai__stage::-webkit-scrollbar-thumb:active {
  background: var(--sa-accent);
  background-clip: padding-box;
}

.study-ai__stage.is-scrolling::-webkit-scrollbar-thumb {
  animation-duration: 0.9s;
  box-shadow:
    0 0 18px color-mix(in srgb, var(--sa-accent) 70%, transparent),
    0 0 6px color-mix(in srgb, var(--sa-accent) 90%, transparent);
}

@keyframes studyAiScrollPulse {
  0% {
    background-position: 0% 0%;
    box-shadow:
      0 0 8px color-mix(in srgb, var(--sa-accent) 35%, transparent),
      0 0 2px color-mix(in srgb, var(--sa-accent) 55%, transparent);
  }
  50% {
    background-position: 0% 100%;
    box-shadow:
      0 0 16px color-mix(in srgb, var(--sa-accent) 65%, transparent),
      0 0 4px color-mix(in srgb, var(--sa-accent) 85%, transparent);
  }
  100% {
    background-position: 0% 200%;
    box-shadow:
      0 0 8px color-mix(in srgb, var(--sa-accent) 35%, transparent),
      0 0 2px color-mix(in srgb, var(--sa-accent) 55%, transparent);
  }
}

.study-ai__empty {
  display: grid;
  gap: 10px;
  justify-items: center;
  align-content: center;
  min-height: 200px;
  height: 100%;
  padding: 24px 20px;
  text-align: center;
  animation: portalPaneIn 480ms var(--sa-ease-out) both;
  transition:
    opacity 280ms var(--sa-ease),
    transform 280ms var(--sa-ease);
}

.study-ai__empty.is-leaving {
  opacity: 0;
  transform: translateY(-8px) scale(0.98);
  pointer-events: none;
}

.study-ai__empty.is-enter {
  animation: portalPaneIn 420ms var(--sa-ease-out) both;
}

.study-ai__empty-mark {
  position: relative;
  width: 56px;
  height: 56px;
  margin-bottom: 4px;
  border-radius: 16px;
  background:
    radial-gradient(circle at 30% 28%, color-mix(in srgb, var(--sa-accent) 45%, transparent), transparent 55%),
    linear-gradient(145deg, var(--sa-accent-soft), color-mix(in srgb, var(--sa-accent) 12%, var(--sa-bg)));
  box-shadow:
    inset 0 0 0 1px color-mix(in srgb, var(--sa-accent) 22%, transparent),
    0 0 24px color-mix(in srgb, var(--sa-accent) 18%, transparent);
  overflow: hidden;
}

.study-ai__empty-orb {
  position: absolute;
  inset: 18% 18%;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, #fff, color-mix(in srgb, var(--sa-accent) 70%, #fff) 45%, transparent 72%);
  box-shadow: 0 0 18px color-mix(in srgb, var(--sa-accent) 45%, transparent);
  animation: studyAiOrb 3.2s ease-in-out infinite;
}

@keyframes studyAiOrb {
  0%, 100% { transform: scale(0.92); opacity: 0.75; }
  50% { transform: scale(1.08); opacity: 1; }
}

.study-ai__empty-title {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 780;
  letter-spacing: -0.035em;
}

.study-ai__empty-text {
  margin: 0;
  max-width: 36ch;
  color: var(--sa-mute);
  font-size: 0.92rem;
  line-height: 1.45;
}

.study-ai__chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
  max-width: 520px;
  margin-top: 8px;
}

.study-ai__chip {
  min-height: 36px;
  padding: 0 14px;
  border: 1px solid var(--sa-line);
  border-radius: 999px;
  color: var(--sa-ink);
  background: var(--sa-bg);
  font-size: 0.82rem;
  font-weight: 650;
  cursor: pointer;
  transition:
    transform 200ms var(--sa-ease-out),
    border-color 200ms var(--sa-ease),
    background-color 200ms var(--sa-ease),
    box-shadow 220ms var(--sa-ease);
}

.study-ai__chip:hover {
  border-color: color-mix(in srgb, var(--sa-accent) 35%, var(--sa-line));
  background: var(--sa-accent-soft);
  color: var(--sa-accent-dark);
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.06);
}

.study-ai__chip:active {
  transform: none;
}

/* Messages */
.study-ai__list {
  display: grid;
  gap: 12px;
  padding: 16px;
}

.study-ai__msg {
  position: relative;
  max-width: min(100%, 640px);
  padding: 12px 14px 14px;
  border: 1px solid var(--sa-line);
  border-radius: 14px;
  opacity: 1;
  transform: none;
}

.study-ai__msg.is-send,
.study-ai__msg.is-receive {
  opacity: 0;
}

.study-ai__msg.is-send.is-in {
  animation: studyAiSendIn 480ms var(--sa-ease-out) both;
}

.study-ai__msg.is-receive.is-in {
  animation: studyAiReceiveIn 520ms var(--sa-ease-out) both;
}

.study-ai__msg.is-settle {
  animation: studyAiSettle 420ms var(--sa-ease-out) both;
}

.study-ai__msg.is-streaming {
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--sa-accent) 18%, transparent);
}

.study-ai__msg.is-thinking {
  min-width: 140px;
}

.study-ai__msg.is-reveal .study-ai__body {
  animation: studyAiReveal 360ms var(--sa-ease-out) both;
}

.study-ai__msg--user {
  justify-self: end;
  background: var(--sa-user);
  border-color: color-mix(in srgb, var(--sa-accent) 22%, var(--sa-line));
}

.study-ai__msg--assistant {
  justify-self: start;
  background: var(--sa-bg);
  box-shadow:
    0 1px 0 color-mix(in srgb, #fff 50%, transparent) inset,
    0 8px 22px color-mix(in srgb, var(--sa-accent) 5%, transparent);
}

.study-ai__msg--assistant::before {
  position: absolute;
  left: 0;
  top: 12px;
  bottom: 12px;
  width: 3px;
  border-radius: 0 3px 3px 0;
  background: linear-gradient(
    180deg,
    color-mix(in srgb, var(--sa-accent) 25%, transparent),
    var(--sa-accent),
    color-mix(in srgb, var(--sa-accent) 25%, transparent)
  );
  box-shadow: 0 0 10px color-mix(in srgb, var(--sa-accent) 35%, transparent);
  content: "";
  opacity: 0.85;
}

.study-ai__msg.is-error {
  border-color: color-mix(in srgb, #f87171 40%, var(--sa-line));
  animation: studyAiShake 420ms var(--sa-ease-out) both;
}

.study-ai__role {
  margin: 0 0 8px;
  color: var(--sa-mute);
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.study-ai__msg--assistant .study-ai__role {
  color: color-mix(in srgb, var(--sa-accent-dark) 55%, var(--sa-mute));
}

.study-ai__body {
  color: var(--sa-ink);
  font-size: 0.95rem;
  line-height: 1.6;
  word-break: break-word;
}

.study-ai__body > :first-child {
  margin-top: 0;
}

.study-ai__body > :last-child {
  margin-bottom: 0;
}

.study-ai__body p {
  margin: 0 0 0.75em;
}

.study-ai__body ul,
.study-ai__body ol,
.study-ai__body .comet-ai__list {
  margin: 0 0 0.85em;
  padding-left: 1.25em;
}

.study-ai__body li + li {
  margin-top: 0.35em;
}

.study-ai__body h1,
.study-ai__body h2,
.study-ai__body h3,
.study-ai__body h4,
.study-ai__body .comet-ai__heading {
  margin: 0.95em 0 0.45em;
  font-weight: 780;
  letter-spacing: -0.03em;
  line-height: 1.25;
}

.study-ai__body h3,
.study-ai__body h4 {
  font-size: 1.02rem;
}

.study-ai__body > .study-ai__sz:first-child,
.study-ai__body > h3:first-child,
.study-ai__body > h2:first-child {
  margin-top: 0;
}

.study-ai__body hr,
.study-ai__body .comet-ai__hr {
  margin: 1em 0;
  border: 0;
  border-top: 1px solid color-mix(in srgb, var(--sa-accent) 16%, var(--sa-line));
}

.study-ai__body blockquote,
.study-ai__body .comet-ai__quote {
  margin: 0.8em 0;
  padding: 0.55em 0.85em;
  border-left: 3px solid color-mix(in srgb, var(--sa-accent) 55%, transparent);
  border-radius: 0 10px 10px 0;
  background: color-mix(in srgb, var(--sa-accent) 6%, var(--sa-soft));
  color: var(--sa-ink);
}

.study-ai__body .comet-ai__callout {
  margin: 0.85em 0;
  padding: 10px 12px;
  border: 1px solid var(--sa-line);
  border-radius: 12px;
  background: color-mix(in srgb, var(--sa-soft) 70%, var(--sa-bg));
}

.study-ai__body .comet-ai__callout strong {
  display: block;
  margin-bottom: 4px;
  color: var(--sa-accent-dark);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.study-ai__body code,
.study-ai__inline-code,
.comet-ai__inline-code {
  padding: 0.1em 0.35em;
  border-radius: 6px;
  background: var(--sa-soft);
  font-family: ui-monospace, "Cascadia Code", Consolas, monospace;
  font-size: 0.86em;
}

.study-ai__code,
.comet-ai__code,
.study-ai__body pre {
  margin: 0.7em 0;
  padding: 12px;
  border: 1px solid var(--sa-line);
  border-radius: 10px;
  background: #0f172a;
  color: #e2e8f0;
  overflow: auto;
  scrollbar-width: thin;
}

.study-ai__body pre code {
  padding: 0;
  background: transparent;
  color: inherit;
  font-size: 0.82rem;
  line-height: 1.5;
}

/* Mixed size / color tags */
.study-ai__sz {
  display: inline;
  font-weight: inherit;
}

.study-ai__c {
  display: inline;
  font-weight: 650;
}

.study-ai__math-fallback {
  font-style: italic;
  font-weight: 650;
  font-feature-settings: "tnum" 1;
}

/* Answer highlight — stroke follows glyph outlines (not a box) */
.study-ai__answer {
  position: relative;
  display: inline-grid;
  place-items: center;
  vertical-align: baseline;
  max-width: 100%;
  margin: 0.12em 0.08em;
  padding: 0.12em 0.15em;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
  isolation: isolate;
  line-height: 1;
}

.study-ai__answer-text {
  position: relative;
  z-index: 0;
  display: inline-block;
  font-weight: 750;
  letter-spacing: -0.01em;
  line-height: 1.35;
}

.study-ai__answer-text > :first-child {
  margin-top: 0;
}

.study-ai__answer-text > :last-child {
  margin-bottom: 0;
}

.study-ai__answer-text p {
  margin: 0;
  display: inline;
}

.study-ai__answer.is-glyph-stroke .study-ai__answer-text.is-ghost {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
  opacity: 0;
  pointer-events: none;
}

.study-ai__answer-svg {
  display: block;
  overflow: visible;
  position: relative;
  z-index: 1;
  pointer-events: none;
}

.study-ai__answer-glyph {
  user-select: none;
}

.study-ai__answer-glyph--fill {
  fill: var(--sa-ink);
  stroke: none;
}

.study-ai__answer-glyph--stroke {
  fill: none;
  stroke: var(--sa-accent);
  stroke-width: 2.35;
  stroke-linecap: round;
  stroke-linejoin: round;
  paint-order: stroke;
  animation: studyAiGlyphStroke 2.2s linear infinite;
}

@keyframes studyAiGlyphStroke {
  to {
    stroke-dashoffset: calc(-1 * var(--glyph-len, 120));
  }
}

/* Complex answers (fractions, lists): no box chrome — just strong text */
.study-ai__answer.is-plain-answer {
  display: inline-block;
  padding: 0.05em 0.1em;
  background: transparent;
  box-shadow: none;
}

.study-ai__answer.is-plain-answer .study-ai__answer-text {
  font-weight: 780;
  color: var(--sa-ink);
  text-shadow:
    0 0 0.55px color-mix(in srgb, var(--sa-accent) 55%, transparent),
    0 0 12px color-mix(in srgb, var(--sa-accent) 18%, transparent);
}

.study-ai__tool-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 10px;
}

.study-ai__tool-chip {
  display: inline-flex;
  align-items: center;
  max-width: 100%;
  padding: 4px 9px;
  border: 1px solid color-mix(in srgb, var(--sa-accent) 28%, var(--sa-line));
  border-radius: 999px;
  background: color-mix(in srgb, var(--sa-accent) 10%, var(--sa-bg));
  color: var(--sa-ink);
  font-size: 0.72rem;
  font-weight: 700;
  line-height: 1.3;
  animation: studyAiFadeUp 360ms var(--sa-ease-out) both;
}

.study-ai__tool-chip.is-error {
  border-color: color-mix(in srgb, #f87171 40%, var(--sa-line));
  background: color-mix(in srgb, #f87171 10%, var(--sa-bg));
}

/* Structured copyable blocks */
.study-ai__block {
  position: relative;
  margin: 0.85em 0;
  padding: 10px 12px 12px;
  border: 1px solid color-mix(in srgb, var(--sa-accent) 16%, var(--sa-line));
  border-radius: 12px;
  background: color-mix(in srgb, var(--sa-accent) 4%, var(--sa-bg));
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--sa-accent) 4%, transparent);
  animation: studyAiFadeUp 380ms var(--sa-ease-out) both;
}

.study-ai__block--answer {
  border-color: color-mix(in srgb, var(--sa-accent) 34%, var(--sa-line));
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--sa-accent) 10%, transparent), transparent 55%),
    color-mix(in srgb, var(--sa-accent-soft) 55%, var(--sa-bg));
  box-shadow:
    0 0 0 1px color-mix(in srgb, var(--sa-accent) 12%, transparent),
    0 8px 22px color-mix(in srgb, var(--sa-accent) 10%, transparent);
}

.study-ai__block--tip {
  border-color: color-mix(in srgb, #0ea5e9 28%, var(--sa-line));
  background: color-mix(in srgb, #0ea5e9 7%, var(--sa-bg));
}

.study-ai__block--key {
  border-color: color-mix(in srgb, #f59e0b 30%, var(--sa-line));
  background: color-mix(in srgb, #f59e0b 8%, var(--sa-bg));
}

.study-ai__block--step {
  border-color: color-mix(in srgb, var(--sa-accent) 18%, var(--sa-line));
}

.study-ai__block-head {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-bottom: 8px;
}

.study-ai__block-num {
  display: grid;
  width: 22px;
  height: 22px;
  place-items: center;
  border-radius: 7px;
  background: color-mix(in srgb, var(--sa-accent) 16%, var(--sa-soft));
  color: var(--sa-accent-dark);
  font-size: 0.72rem;
  font-weight: 800;
  line-height: 1;
}

.study-ai__block-label {
  flex: 1;
  min-width: 0;
  color: color-mix(in srgb, var(--sa-accent-dark) 70%, var(--sa-mute));
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.study-ai__block-copy,
.study-ai__action,
.study-ai__follow,
.study-ai__saved-clear {
  min-height: 28px;
  padding: 0 10px;
  border: 1px solid var(--sa-line);
  border-radius: 8px;
  color: var(--sa-mute);
  background: color-mix(in srgb, var(--sa-bg) 88%, transparent);
  font-size: 0.72rem;
  font-weight: 750;
  cursor: pointer;
  transition:
    color 180ms var(--sa-ease),
    border-color 180ms var(--sa-ease),
    background-color 180ms var(--sa-ease),
    transform 160ms var(--sa-ease-out),
    box-shadow 200ms var(--sa-ease);
}

.study-ai__block-copy:hover,
.study-ai__action:hover,
.study-ai__follow:hover,
.study-ai__saved-clear:hover {
  color: var(--sa-ink);
  border-color: color-mix(in srgb, var(--sa-accent) 35%, var(--sa-line));
  background: var(--sa-accent-soft);
}

.study-ai__block-copy.is-copied,
.study-ai__action.is-copied,
.study-ai__saved-item.is-copied {
  color: var(--sa-accent-dark);
  border-color: color-mix(in srgb, var(--sa-accent) 40%, var(--sa-line));
  box-shadow: 0 0 12px color-mix(in srgb, var(--sa-accent) 18%, transparent);
}

.study-ai__block-body > :first-child {
  margin-top: 0;
}

.study-ai__block-body > :last-child {
  margin-bottom: 0;
}

.study-ai__block-body p {
  margin: 0 0 0.45em;
}

.study-ai__msg-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 12px;
  opacity: 0;
  transform: translateY(4px);
}

.study-ai__msg-actions.is-fade-in,
.study-ai__followups.is-fade-in {
  animation: studyAiFadeUp 360ms var(--sa-ease-out) 80ms both;
}

.study-ai__followups {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
  opacity: 0;
  transform: translateY(4px);
}

.study-ai__follow {
  border-radius: 999px;
  border-color: color-mix(in srgb, var(--sa-accent) 18%, var(--sa-line));
  color: color-mix(in srgb, var(--sa-accent-dark) 55%, var(--sa-mute));
}

.study-ai__follow:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px color-mix(in srgb, var(--sa-accent) 12%, transparent);
}

.study-ai__follow--topic {
  border-color: color-mix(in srgb, var(--sa-accent) 28%, var(--sa-line));
  background: color-mix(in srgb, var(--sa-accent) 8%, var(--sa-bg));
  color: var(--sa-accent-dark);
}

.study-ai__action[hidden] {
  display: none !important;
}

/* Saved answers tray */
.study-ai__saved {
  padding: 10px 12px;
  border: 1px solid color-mix(in srgb, var(--sa-accent) 18%, var(--sa-line));
  border-radius: 12px;
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--sa-accent) 8%, transparent), transparent 40%),
    color-mix(in srgb, var(--sa-bg) 92%, var(--sa-soft));
  animation: studyAiFadeUp 320ms var(--sa-ease-out) both;
}

.study-ai__saved-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 8px;
}

.study-ai__saved-title {
  color: var(--sa-accent-dark);
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.study-ai__saved-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.study-ai__saved-item {
  max-width: 100%;
  min-height: 30px;
  padding: 0 11px;
  overflow: hidden;
  border: 1px solid color-mix(in srgb, var(--sa-accent) 20%, var(--sa-line));
  border-radius: 999px;
  color: var(--sa-ink);
  background: var(--sa-bg);
  font-size: 0.75rem;
  font-weight: 650;
  text-overflow: ellipsis;
  white-space: nowrap;
  cursor: pointer;
  transition:
    transform 180ms var(--sa-ease-out),
    border-color 180ms var(--sa-ease),
    box-shadow 200ms var(--sa-ease);
}

.study-ai__saved-item:hover {
  border-color: color-mix(in srgb, var(--sa-accent) 45%, var(--sa-line));
  transform: translateY(-1px);
  box-shadow: 0 4px 14px color-mix(in srgb, var(--sa-accent) 12%, transparent);
}

.study-ai__copy {
  margin-top: 10px;
  min-height: 30px;
  padding: 0 10px;
  border: 1px solid var(--sa-line);
  border-radius: 8px;
  color: var(--sa-mute);
  background: transparent;
  font-size: 0.74rem;
  font-weight: 700;
  opacity: 0;
  transform: translateY(4px);
}

.study-ai__copy.is-fade-in {
  animation: studyAiFadeUp 360ms var(--sa-ease-out) 80ms both;
}

.study-ai__copy:hover {
  color: var(--sa-ink);
  background: var(--sa-soft);
}

.study-ai__copy.is-copied {
  color: var(--sa-accent-dark);
  border-color: color-mix(in srgb, var(--sa-accent) 35%, var(--sa-line));
}

/* Thinking / generating dots */
.study-ai__thinking {
  display: inline-flex;
  gap: 5px;
  align-items: center;
  margin-right: 10px;
  vertical-align: middle;
}

.study-ai__dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--sa-accent);
  opacity: 0.35;
  animation: studyAiDot 1.15s var(--sa-ease) infinite;
}

.study-ai__dot:nth-child(2) {
  animation-delay: 0.15s;
}

.study-ai__dot:nth-child(3) {
  animation-delay: 0.3s;
}

.study-ai__thinking-label {
  color: var(--sa-mute);
  font-size: 0.88rem;
  font-weight: 650;
  letter-spacing: -0.01em;
  background: linear-gradient(
    90deg,
    var(--sa-mute) 0%,
    var(--sa-ink) 40%,
    var(--sa-mute) 80%
  );
  background-size: 200% 100%;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  animation: studyAiShimmer 1.6s linear infinite;
}

.study-ai__cursor,
.comet-ai__stream-cursor {
  display: inline-block;
  width: 0.45em;
  height: 1em;
  margin-left: 2px;
  border-radius: 2px;
  background: var(--sa-accent);
  vertical-align: -0.15em;
  animation: studyAiBlink 1s steps(1) infinite;
}

@keyframes studyAiBlink {
  50% { opacity: 0; }
}

@keyframes studyAiSendIn {
  from {
    opacity: 0;
    transform: translate3d(0, 16px, 0) scale(0.96);
  }
  to {
    opacity: 1;
    transform: translate3d(0, 0, 0) scale(1);
  }
}

@keyframes studyAiFlightLand {
  from {
    opacity: 0.85;
    transform: translate3d(0, 4px, 0) scale(0.985);
  }
  to {
    opacity: 1;
    transform: translate3d(0, 0, 0) scale(1);
  }
}

@keyframes studyAiReceiveIn {
  from {
    opacity: 0;
    transform: translateY(14px) translateX(-8px) scale(0.96);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes studyAiSettle {
  from {
    box-shadow: 0 0 0 1px color-mix(in srgb, var(--sa-accent) 22%, transparent);
  }
  to {
    box-shadow: none;
  }
}

@keyframes studyAiReveal {
  from {
    opacity: 0.35;
    filter: blur(2px);
  }
  to {
    opacity: 1;
    filter: none;
  }
}

@keyframes studyAiDot {
  0%,
  80%,
  100% {
    opacity: 0.3;
    transform: translateY(0) scale(0.9);
  }
  40% {
    opacity: 1;
    transform: translateY(-3px) scale(1.1);
  }
}

@keyframes studyAiShimmer {
  from { background-position: 100% center; }
  to { background-position: -100% center; }
}

@keyframes studyAiFadeUp {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes studyAiShake {
  0%,
  100% { transform: translateX(0); }
  25% { transform: translateX(-4px); }
  75% { transform: translateX(4px); }
}

/* Composer */
.study-ai__composer {
  position: relative;
  z-index: 5;
  flex: 0 0 auto;
  display: grid;
  gap: 8px;
  padding: 12px;
  border: 1px solid var(--sa-line);
  border-radius: var(--sa-radius);
  background: var(--sa-bg);
  transform-origin: center bottom;
  transition:
    border-color 280ms var(--sa-ease),
    box-shadow 320ms var(--sa-ease),
    transform 320ms var(--sa-ease-out),
    padding 280ms var(--sa-ease),
    border-radius 280ms var(--sa-ease),
    background-color 280ms var(--sa-ease);
}

/* Soft aura behind the box — Gemini-style lift on focus */
.study-ai__composer::before {
  position: absolute;
  inset: -18%;
  z-index: -1;
  border-radius: 28px;
  background: radial-gradient(
    closest-side,
    color-mix(in srgb, var(--sa-accent) 28%, transparent),
    transparent 72%
  );
  opacity: 0;
  transform: scale(0.86);
  content: "";
  pointer-events: none;
  transition:
    opacity 360ms var(--sa-ease),
    transform 420ms var(--sa-ease-out);
}

.study-ai__composer::after {
  position: absolute;
  inset: -1px;
  z-index: -1;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(
    120deg,
    color-mix(in srgb, var(--sa-accent) 55%, transparent),
    transparent 35%,
    transparent 65%,
    color-mix(in srgb, var(--sa-accent) 40%, transparent)
  );
  background-size: 220% 100%;
  opacity: 0;
  content: "";
  pointer-events: none;
  transition: opacity 280ms var(--sa-ease);
  -webkit-mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
}

.study-ai__composer.is-focused,
.study-ai__composer:focus-within {
  padding: 14px 14px 12px;
  border-color: color-mix(in srgb, var(--sa-accent) 42%, var(--sa-line));
  border-radius: 18px;
  background: color-mix(in srgb, var(--sa-bg) 92%, #fff);
  /* Lift without clipping — scale + glow only */
  transform: translateY(-2px) scale(1.012);
  box-shadow:
    0 0 0 1px color-mix(in srgb, var(--sa-accent) 16%, transparent),
    0 14px 36px color-mix(in srgb, var(--sa-accent) 14%, transparent),
    0 4px 14px rgba(15, 23, 42, 0.08);
}

.study-ai__composer.is-focused::before,
.study-ai__composer:focus-within::before {
  opacity: 1;
  transform: scale(1);
}

.study-ai__composer.is-focused::after,
.study-ai__composer:focus-within::after {
  opacity: 0.9;
  animation: studyAiFocusSheen 2.8s linear infinite;
}

.study-ai__composer.is-focus-pulse {
  animation: studyAiFocusPop 480ms var(--sa-ease-out);
}

@keyframes studyAiFocusSheen {
  from { background-position: 0% 50%; }
  to { background-position: 200% 50%; }
}

@keyframes studyAiFocusPop {
  0% { transform: translateY(0) scale(1); }
  45% { transform: translateY(-3px) scale(1.02); }
  100% { transform: translateY(-2px) scale(1.012); }
}

#hwStudyAi.is-generating .study-ai__composer {
  border-color: color-mix(in srgb, var(--sa-accent) 28%, var(--sa-line));
  box-shadow:
    0 0 0 3px color-mix(in srgb, var(--sa-accent) 10%, transparent),
    0 10px 28px color-mix(in srgb, var(--sa-accent) 10%, transparent);
}

/* Flying send clone — blank shape only (no text while traveling) */
.study-ai__flight {
  position: fixed;
  left: 0;
  top: 0;
  z-index: 9999;
  box-sizing: border-box;
  display: block;
  padding: 0;
  border: 1px solid color-mix(in srgb, var(--sa-accent) 18%, var(--sa-line));
  border-radius: 12px;
  background: color-mix(in srgb, var(--sa-soft) 55%, var(--sa-bg));
  overflow: visible;
  pointer-events: none;
  transform-origin: top left;
  will-change: transform;
  backface-visibility: hidden;
}

.study-ai__flight.is-field {
  background: color-mix(in srgb, var(--sa-soft) 60%, var(--sa-bg));
  border-color: color-mix(in srgb, var(--sa-accent) 22%, var(--sa-line));
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--sa-accent) 8%, transparent);
}

.study-ai__flight.is-bubble,
.study-ai__flight.is-blank {
  background: var(--sa-user);
  border-color: color-mix(in srgb, var(--sa-accent) 28%, var(--sa-line));
  box-shadow:
    0 10px 28px color-mix(in srgb, var(--sa-accent) 18%, transparent),
    0 2px 8px rgba(15, 23, 42, 0.06);
}

.study-ai__msg.is-flight-wait {
  opacity: 0 !important;
  pointer-events: none;
  transform: none !important;
  animation: none !important;
}

.study-ai__msg.is-flight-land {
  animation: studyAiFlightLand 160ms cubic-bezier(0.22, 1, 0.36, 1) both;
}

.study-ai__list.is-clearing {
  animation: studyAiListClear 220ms var(--sa-ease) both;
}

.study-ai__status {
  flex: 1;
  min-width: 0;
  color: var(--sa-mute);
  font-size: 0.78rem;
  font-weight: 600;
  opacity: 0;
  transform: translateY(4px);
  transition:
    opacity 200ms var(--sa-ease),
    transform 200ms var(--sa-ease),
    color 200ms var(--sa-ease);
}

.study-ai__status.is-pop {
  opacity: 1;
  transform: none;
}

.study-ai__status.is-thinking {
  color: var(--sa-accent-dark);
}

.study-ai__status.is-writing {
  color: var(--sa-accent-dark);
}

.study-ai__status.is-sending {
  color: var(--sa-mute);
}

.study-ai__status.is-done {
  color: color-mix(in srgb, #22c55e 70%, var(--sa-mute));
}

.study-ai__send.is-busy {
  position: relative;
  overflow: hidden;
}

.study-ai__send.is-busy::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    105deg,
    transparent 30%,
    rgba(255, 255, 255, 0.22) 50%,
    transparent 70%
  );
  transform: translateX(-120%);
  animation: studyAiSendShine 1.1s var(--sa-ease) infinite;
}

.study-ai__stop.is-in {
  animation: studyAiFadeUp 280ms var(--sa-ease-out) both;
}

@keyframes studyAiListClear {
  to {
    opacity: 0;
    transform: translateY(8px);
  }
}

@keyframes studyAiSendShine {
  to {
    transform: translateX(120%);
  }
}

.study-ai__input {
  width: 100%;
  min-height: 44px;
  max-height: 110px;
  padding: 10px 12px;
  border: 1px solid var(--sa-line);
  border-radius: 11px;
  color: var(--sa-ink);
  background: color-mix(in srgb, var(--sa-soft) 55%, var(--sa-bg));
  font: inherit;
  font-size: 0.95rem;
  line-height: 1.4;
  resize: none;
  outline: none;
  transition:
    border-color 240ms var(--sa-ease),
    box-shadow 280ms var(--sa-ease),
    background-color 240ms var(--sa-ease),
    min-height 280ms var(--sa-ease),
    padding 240ms var(--sa-ease);
}

.study-ai__composer.is-focused .study-ai__input,
.study-ai__composer:focus-within .study-ai__input {
  min-height: 56px;
  padding: 12px 14px;
  border-color: transparent;
  background: color-mix(in srgb, var(--sa-soft) 35%, var(--sa-bg));
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--sa-accent) 12%, transparent);
}

.study-ai__input:focus {
  border-color: transparent;
  box-shadow: none;
}

.study-ai__input::placeholder {
  color: var(--sa-mute);
  transition: opacity 220ms var(--sa-ease), transform 220ms var(--sa-ease);
}

.study-ai__composer.is-focused .study-ai__input::placeholder,
.study-ai__composer:focus-within .study-ai__input::placeholder {
  opacity: 0.55;
  transform: translateX(2px);
}

.study-ai__actions {
  display: flex;
  gap: 8px;
  align-items: center;
  justify-content: flex-end;
}

.study-ai__send,
.study-ai__stop {
  min-height: 40px;
  padding: 0 16px;
  border-radius: 11px;
  font-size: 0.88rem;
  font-weight: 750;
  transition:
    transform 180ms var(--sa-ease-out),
    background-color 200ms var(--sa-ease),
    border-color 200ms var(--sa-ease);
}

.study-ai__send {
  border: 1px solid var(--sa-accent);
  color: #fff;
  background: var(--sa-accent);
}

.study-ai__send:hover:not(:disabled) {
  background: var(--sa-accent-dark);
  border-color: var(--sa-accent-dark);
}

.study-ai__send:disabled {
  opacity: 0.55;
  cursor: default;
}

.study-ai__stop {
  border: 1px solid var(--sa-line-strong);
  color: var(--sa-ink);
  background: var(--sa-soft);
}

.study-ai__stop:hover {
  border-color: var(--sa-ink);
}

.study-ai__send:active,
.study-ai__stop:active {
  transform: scale(0.97);
}

/* Math / rich content from shared formatter */
.study-ai__body .katex,
.study-ai__body .study-ai__math,
.study-ai__body .comet-ai__math {
  font-size: 1.08em;
  color: var(--sa-ink);
  text-rendering: geometricPrecision;
}

.study-ai__body .katex-display,
.study-ai__body .comet-ai__math--block {
  margin: 0.85em 0;
  padding: 0.55em 0.4em;
  overflow-x: auto;
  overflow-y: hidden;
  border-radius: 10px;
  background: color-mix(in srgb, var(--sa-accent) 5%, var(--sa-soft));
  scrollbar-width: thin;
}

.study-ai__body .katex-display > .katex,
.study-ai__body .comet-ai__math--block .katex {
  font-size: 1.18em;
  text-align: center;
}

.study-ai__body .comet-ai__math--inline,
.study-ai__body .comet-ai__math--inline .katex {
  padding: 0 0.12em;
  border-radius: 4px;
}

.study-ai__body .comet-ai__math-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 6px;
  padding: 0 4px;
}

.study-ai__body .comet-ai__math-label {
  color: var(--sa-mute);
  font-size: 0.7rem;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.study-ai__body .comet-ai__math-copy {
  min-height: 26px;
  padding: 0 8px;
  border: 1px solid var(--sa-line);
  border-radius: 7px;
  color: var(--sa-mute);
  background: var(--sa-bg);
  font-size: 0.7rem;
  font-weight: 700;
  cursor: pointer;
}

.study-ai__body .comet-ai__math-copy:hover {
  color: var(--sa-ink);
  border-color: var(--sa-line-strong);
}

.study-ai__answer .katex,
.study-ai__answer .comet-ai__math {
  font-size: 1.12em;
}

.study-ai__body .comet-ai__md-table-wrap {
  overflow-x: auto;
  margin: 0.7em 0;
}

.study-ai__body table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.88rem;
}

.study-ai__body th,
.study-ai__body td {
  padding: 6px 10px;
  border: 1px solid var(--sa-line);
  text-align: left;
}

@media (max-width: 700px) {
  .study-ai,
  #hwStudyAi {
    --sa-chat-h: min(460px, calc(100dvh - 140px));
    min-height: 300px;
  }

  #hwStudyAi {
    gap: 8px;
  }

  .study-ai__stage {
    min-height: 140px;
  }

  .study-ai__stage::-webkit-scrollbar {
    width: 9px;
  }

  .study-ai__empty {
    min-height: 140px;
    padding: 18px 14px;
  }

  .study-ai__list {
    padding: 12px;
  }

  .study-ai__msg {
    padding: 11px 12px 12px;
  }

  .study-ai__composer.is-focused,
  .study-ai__composer:focus-within {
    transform: translateY(-1px) scale(1.008);
  }
}

@media (prefers-reduced-motion: reduce) {
  #hwStudyAi,
  .study-ai__empty,
  .study-ai__msg,
  .study-ai__msg.is-send.is-in,
  .study-ai__msg.is-receive.is-in,
  .study-ai__msg.is-settle,
  .study-ai__msg.is-error,
  .study-ai__copy.is-fade-in,
  .study-ai__msg-actions.is-fade-in,
  .study-ai__followups.is-fade-in,
  .study-ai__block,
  .study-ai__empty-orb,
  .study-ai__cursor,
  .comet-ai__stream-cursor,
  .study-ai__dot,
  .study-ai__thinking-label,
  .study-ai__send.is-busy::after,
  .study-ai__stop.is-in,
  #hwStudyAi.is-sent-flash .study-ai__composer,
  #hwStudyAi.is-sending-motion .study-ai__composer,
  #hwStudyAi.is-sending-motion .study-ai__send,
  .study-ai__composer.is-focus-pulse,
  .study-ai__composer::after,
  .study-ai__send-ripple,
  .study-ai__send-ghost,
  .study-ai__flight,
  .study-ai__msg.is-flight-land,
  .study-ai__list.is-clearing,
  .study-ai__answer-glyph--stroke,
  .study-ai__stage::-webkit-scrollbar-thumb {
    animation: none !important;
  }

  .study-ai__composer.is-focused,
  .study-ai__composer:focus-within {
    transform: none;
  }

  .study-ai__composer::before {
    opacity: 0 !important;
  }

  .study-ai__answer-glyph--stroke {
    stroke-dasharray: none;
    stroke-width: 1.6;
    opacity: 0.9;
  }

  .study-ai__msg.is-send,
  .study-ai__msg.is-receive,
  .study-ai__copy,
  .study-ai__status {
    opacity: 1 !important;
    transform: none !important;
  }
}