* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: #17202a;
  background: #f4f6f8;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.chat-shell {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  min-height: 100vh;
}

.channels {
  padding: 20px;
  border-right: 1px solid #d8dee4;
  background: #ffffff;
}

.channels h1 {
  margin: 0 0 18px;
  font-size: 22px;
}

.login-form {
  display: grid;
  gap: 10px;
  margin-bottom: 20px;
}

.login-form label {
  display: grid;
  gap: 5px;
  color: #4d5b6a;
  font-size: 13px;
}

input,
button {
  height: 40px;
  border-radius: 6px;
  font: inherit;
}

input {
  min-width: 0;
  padding: 0 10px;
  border: 1px solid #c8d1da;
  background: #ffffff;
}

button {
  border: 0;
  padding: 0 14px;
  background: #1f6feb;
  color: #ffffff;
  cursor: pointer;
}

button:disabled,
input:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.channel-button {
  width: 100%;
  margin-bottom: 8px;
  border: 1px solid #c8d1da;
  background: #f8fafb;
  color: #17202a;
  text-align: left;
}

.channel-button.active {
  border-color: #1f6feb;
  background: #eaf2ff;
}

.conversation {
  display: grid;
  grid-template-rows: auto 1fr auto;
  min-width: 0;
}

.conversation header,
.composer {
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 64px;
  padding: 12px 20px;
  background: #ffffff;
}

.conversation header {
  border-bottom: 1px solid #d8dee4;
}

.conversation header span {
  color: #637083;
  font-size: 14px;
}

.messages {
  padding: 20px;
  overflow: auto;
}

.empty,
.system-message {
  color: #637083;
}

.chat-message {
  display: flex;
  gap: 10px;
  max-width: 820px;
  margin-bottom: 10px;
  line-height: 1.4;
}

.chat-message strong {
  flex: 0 0 140px;
  overflow-wrap: anywhere;
}

.chat-message span {
  min-width: 0;
  overflow-wrap: anywhere;
}

.own-message span {
  color: #0b5cad;
}

.composer {
  border-top: 1px solid #d8dee4;
}

.composer input {
  flex: 1;
}

@media (max-width: 760px) {
  .chat-shell {
    grid-template-columns: 1fr;
  }

  .channels {
    border-right: 0;
    border-bottom: 1px solid #d8dee4;
  }
}