:root {
  --bg: #f6f7fb;
  --panel: #ffffff;
  --text: #1c2233;
  --muted: #6b7388;
  --brand: #3b5bdb;
  --brand-ink: #ffffff;
  --user: #3b5bdb;
  --bot: #eef1f8;
  --border: #e1e5ef;
  --danger: #c92a2a;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151f;
    --panel: #1a1f2e;
    --text: #e8ebf5;
    --muted: #9aa3ba;
    --brand: #6d86ff;
    --brand-ink: #0e1220;
    --user: #34457f;
    --bot: #232a3d;
    --border: #2b3249;
    --danger: #ff8787;
  }
}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Noto Sans Bengali", "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  line-height: 1.65;
}

.app {
  max-width: 820px;
  height: 100%;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  padding: 0 16px;
}

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 14px 0 10px;
  border-bottom: 1px solid var(--border);
}

.brand { display: flex; align-items: center; gap: 10px; }
.logo { font-size: 28px; }
h1 { margin: 0; font-size: 20px; line-height: 1.2; }
.tagline { margin: 0; font-size: 13px; color: var(--muted); }

.controls { display: flex; align-items: center; gap: 8px; }

.lang {
  display: inline-flex;
  border: 1px solid var(--border);
  border-radius: 999px;
  overflow: hidden;
  background: var(--panel);
}
.lang button {
  border: 0;
  background: transparent;
  color: var(--muted);
  padding: 6px 14px;
  font: inherit;
  font-size: 14px;
  cursor: pointer;
}
.lang button.active { background: var(--brand); color: var(--brand-ink); font-weight: 600; }

button.ghost {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 999px;
  padding: 6px 14px;
  font: inherit;
  font-size: 14px;
  cursor: pointer;
}
button:focus-visible, textarea:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
}

.chat {
  flex: 1;
  overflow-y: auto;
  padding: 18px 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.msg {
  max-width: 88%;
  padding: 10px 14px;
  border-radius: 16px;
  word-wrap: break-word;
  overflow-wrap: anywhere;
}
.msg.user {
  align-self: flex-end;
  background: var(--user);
  color: #fff;
  border-bottom-right-radius: 4px;
  white-space: pre-wrap;
}
.msg.bot {
  align-self: flex-start;
  background: var(--bot);
  border-bottom-left-radius: 4px;
}
.msg.error { color: var(--danger); border: 1px solid var(--danger); background: transparent; }
.msg.bot p { margin: 0 0 8px; }
.msg.bot p:last-child, .msg.bot ul:last-child, .msg.bot ol:last-child { margin-bottom: 0; }
.msg.bot ul, .msg.bot ol { margin: 0 0 8px; padding-left: 22px; }
.msg.bot code {
  background: rgba(127, 127, 127, 0.18);
  padding: 1px 5px;
  border-radius: 5px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.92em;
}
.msg.bot pre {
  background: rgba(127, 127, 127, 0.16);
  padding: 10px 12px;
  border-radius: 10px;
  overflow-x: auto;
  margin: 0 0 8px;
}
.msg.bot pre code { background: transparent; padding: 0; }

.typing { color: var(--muted); }
.typing::after { content: "…"; animation: blink 1s infinite; }
@keyframes blink { 50% { opacity: 0.2; } }

.suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding-bottom: 10px;
}
.suggestions button {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 999px;
  padding: 6px 12px;
  font: inherit;
  font-size: 13px;
  cursor: pointer;
}
.suggestions.hidden { display: none; }

.composer {
  display: flex;
  gap: 8px;
  align-items: flex-end;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 8px;
}
.composer textarea {
  flex: 1;
  border: 0;
  resize: none;
  background: transparent;
  color: var(--text);
  font: inherit;
  max-height: 160px;
  padding: 6px 8px;
}
.composer textarea:focus-visible { outline: none; }
.composer button {
  border: 0;
  background: var(--brand);
  color: var(--brand-ink);
  font: inherit;
  font-weight: 600;
  border-radius: 12px;
  padding: 9px 18px;
  cursor: pointer;
}
.composer button:disabled { opacity: 0.5; cursor: not-allowed; }

.note {
  margin: 8px 0 12px;
  font-size: 12px;
  color: var(--muted);
  text-align: center;
}

@media (max-width: 520px) {
  .msg { max-width: 94%; }
}