:root {
  --bg: #f7f7f4;
  --panel: #ffffff;
  --sidebar: #171717;
  --sidebar-soft: #242424;
  --text: #202123;
  --muted: #6f6f6f;
  --line: #deded8;
  --accent: #10a37f;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  grid-template-columns: 260px 1fr;
  color: var(--text);
  background: var(--bg);
  font-family: Arial, "Malgun Gothic", sans-serif;
}

.sidebar {
  min-height: 100vh;
  padding: 12px;
  color: white;
  background: var(--sidebar);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.new-chat,
.history-item {
  width: 100%;
  min-height: 42px;
  border: 1px solid #3a3a3a;
  border-radius: 8px;
  color: white;
  background: transparent;
  text-align: left;
  padding: 0 12px;
  font-size: 14px;
  cursor: pointer;
}

.history {
  flex: 1;
}

.history-item.active {
  background: var(--sidebar-soft);
}

.model {
  padding: 12px;
  border-top: 1px solid #333;
  color: #cfcfcf;
  font-size: 13px;
}

.chat-shell {
  min-width: 0;
  min-height: 100vh;
  display: grid;
  grid-template-rows: 58px 1fr auto;
}

.topbar {
  display: flex;
  align-items: center;
  padding: 0 24px;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.8);
}

.topbar div {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.topbar span {
  color: var(--muted);
  font-size: 13px;
}

.messages {
  width: min(860px, 100%);
  margin: 0 auto;
  padding: 28px 20px 120px;
  overflow: auto;
}

.message {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 14px;
  margin: 0 0 24px;
}

.avatar {
  width: 34px;
  height: 34px;
  border-radius: 6px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--accent);
  font-weight: 700;
}

.message.user .avatar {
  background: #565869;
}

.bubble {
  max-width: 100%;
  padding: 6px 0;
  line-height: 1.65;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.composer {
  position: fixed;
  left: 260px;
  right: 0;
  bottom: 0;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  width: min(860px, calc(100% - 300px));
  margin: 0 auto;
  padding: 18px 20px 22px;
  background: linear-gradient(to top, var(--bg) 80%, rgba(247, 247, 244, 0));
}

textarea {
  min-height: 52px;
  max-height: 180px;
  resize: none;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px 16px;
  font: inherit;
  line-height: 1.4;
  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.08);
}

textarea:focus {
  border-color: var(--accent);
  outline: none;
}

#sendButton {
  align-self: end;
  min-width: 72px;
  height: 52px;
  border: 0;
  border-radius: 8px;
  color: white;
  background: var(--accent);
  font-weight: 700;
  cursor: pointer;
}

#sendButton:disabled {
  cursor: wait;
  opacity: 0.6;
}

@media (max-width: 720px) {
  body {
    grid-template-columns: 1fr;
  }

  .sidebar {
    display: none;
  }

  .composer {
    left: 0;
    width: 100%;
  }
}