:root {
  --bg-main: #18181b;
  --bg-chat: #23232a;
  --bg-user: #3b82f6;
  --bg-assistant: #27272a;
  --text-main: #f3f4f6;
  --text-secondary: #a1a1aa;
  --accent: #ef4444;
  --border: #31313a;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
  --radius: 14px;
}
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: "Segoe UI", "Arial", sans-serif;
  background: var(--bg-main);
  color: var(--text-main);
  width: 100vw;
  height: 100vh;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: background 0.3s;
  min-height: 100vh;
  min-width: 100vw;
  overflow: hidden;
}
#chat-container {
  display: flex;
  flex-direction: column;
  width: 100vw;
  max-width: 750px;
  height: 100vh;
  max-height: 100vh;
  background: var(--bg-chat);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  border: 1px solid var(--border);
  position: relative;
}
#chat-container::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 6px;
  background: linear-gradient(90deg, var(--accent), #f59e42, #22d3ee);
  border-top-left-radius: var(--radius);
  border-top-right-radius: var(--radius);
  opacity: 0.7;
  z-index: 2;
}
#header {
  padding: 18px 20px 10px 20px;
  background: transparent;
  text-align: center;
  font-size: 1.5rem;
  font-weight: bold;
  letter-spacing: 1px;
  color: var(--accent);
  text-shadow: 0 2px 8px #0006;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  border-bottom: 1px solid var(--border);
  z-index: 3;
}
#header svg {
  width: 32px;
  height: 32px;
  vertical-align: middle;
  filter: drop-shadow(0 2px 4px #0008);
}
#messages {
  flex: 1;
  padding: 18px 16px 18px 16px;
  overflow-y: auto;
  background: var(--bg-chat);
  border-bottom: 1px solid var(--border);
  scrollbar-width: thin;
  scrollbar-color: var(--accent) var(--bg-chat);
  min-height: 0;
  max-height: calc(100vh - 120px);
  display: flex;
  flex-direction: column;
  align-items: stretch;
}
#messages::-webkit-scrollbar {
  width: 8px;
  background: var(--bg-chat);
}
#messages::-webkit-scrollbar-thumb {
  background: var(--accent);
  border-radius: 8px;
}
.message {
  margin: 12px 4px 12px 4px;
  padding: 12px 18px;
  border-radius: 12px;
  display: block;
  width: fit-content;
  align-self: flex-start;
  max-width: 95%;
  word-break: break-word;
  font-size: 0.95rem;
  box-shadow: 0 2px 8px #0002;
  transition: background 0.2s;
  position: relative;
  width: fit-content;
  min-width: 20px;
  clear: both;
}
.user {
  background: linear-gradient(90deg, var(--bg-user) 80%, #2563eb 100%);
  color: #fff;
  align-self: flex-end;
  text-align: right;
  border-bottom-right-radius: 2px;
  border-top-right-radius: 18px;
  border-top-left-radius: 18px;
  border-bottom-left-radius: 18px;
}
.assistant {
  background: var(--bg-assistant);
  color: var(--text-secondary);
  align-self: flex-start;
  text-align: left;
  border-bottom-left-radius: 2px;
  border-top-right-radius: 18px;
  border-top-left-radius: 18px;
  border-bottom-right-radius: 18px;
}
.message::after {
  content: "";
  display: block;
  clear: both;
}
#input-container {
  display: flex;
  border-top: 1px solid var(--border);
  background: #1e1e23;
  padding: 10px 12px;
  gap: 8px;
  position: sticky;
  bottom: 0;
  z-index: 5;
}
#input-container input {
  flex: 2;
  border: none;
  padding: 12px 14px;
  font-size: 0.95rem;
  border-radius: 8px;
  background: #23232a;
  color: var(--text-main);
  outline: none;
  transition: background 0.2s;
  box-shadow: 0 2px 8px #0002;
}
#input-container input:focus {
  background: #18181b;
  border: 1px solid var(--accent);
}
#input-container button {
  padding: 0 22px;
  border: none;
  background: linear-gradient(90deg, var(--accent), #f59e42);
  color: #fff;
  font-weight: bold;
  font-size: 1.08rem;
  border-radius: 8px;
  cursor: pointer;
  box-shadow: 0 2px 8px #0002;
  transition: background 0.2s, transform 0.1s;
  outline: none;
}
#input-container button:hover {
  background: linear-gradient(90deg, #f59e42, var(--accent));
  transform: scale(1.04);
}
@media (max-width: 900px) {
  #chat-container {
    max-width: 100vw;
    width: 100vw;
    border-radius: 0;
    box-shadow: none;
    height: 100vh;
  }
  #header {
    font-size: 1.2rem;
    padding: 12px 8px 6px 8px;
  }
  #messages {
    padding: 10px 6px 10px 6px;
    max-height: calc(100vh - 110px);
  }
  #input-container {
    padding: 8px 4px;
  }
}
@media (max-width: 600px) {
  #chat-container {
    width: 100vw;
    border-radius: 0;
    box-shadow: none;
    height: 100vh;
  }
  #header {
    font-size: 1.1rem;
    padding: 10px 4px 4px 4px;
  }
  #messages {
    padding: 6px 2px 6px 2px;
    max-height: calc(100vh - 100px);
  }
  #input-container {
    padding: 6px 2px;
  }
}