:root {
  --bg-color: #1c1c1e;
  --surface-color: #2c2c2e;
  --primary-color: #0a84ff;
  --text-color: #f2f2f7;
  --subtle-text-color: #8e8e93;
  --border-color: #3a3a3c;
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  color: var(--text-color);
  font-family: var(--font-family);
  background-color: var(--bg-color);
  font-size: 16px;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  overflow: hidden;
}

#app-container {
  width: 95vw;
  max-width: 1200px;
  height: 90vh;
  background: var(--surface-color);
  border-radius: 12px;
  border: 1px solid var(--border-color);
  display: flex;
  overflow: hidden;
  box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

#sidebar {
  width: 260px;
  background: var(--bg-color);
  display: flex;
  flex-direction: column;
  padding: 16px;
  border-right: 1px solid var(--border-color);
}

.sidebar-header h2 {
  margin: 0 0 16px 8px;
  font-size: 1.4em;
  font-weight: 600;
}

#room-list {
  list-style: none;
  padding: 0;
  margin: 0;
  flex-grow: 1;
  overflow-y: auto;
}

.room-item {
  padding: 12px 16px;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s ease;
  margin-bottom: 4px;
  font-weight: 500;
}

.room-item:hover {
  background-color: rgba(255, 255, 255, 0.05);
}

.room-item.active {
  background-color: var(--primary-color);
  color: #fff;
  font-weight: 600;
}

.sidebar-footer {
  margin-top: auto;
  padding-top: 16px;
  border-top: 1px solid var(--border-color);
}

#user-info-btn {
  width: 100%;
  background: transparent;
  color: var(--text-color);
  border: 1px solid var(--border-color);
  padding: 10px 15px;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s ease, border-color 0.2s ease;
  font-weight: 500;
  font-family: var(--font-family);
}

#user-info-btn:hover {
  background-color: var(--border-color);
  border-color: var(--subtle-text-color);
}

#chat-area {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  background-color: var(--surface-color);
}

#chat-area header {
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-shrink: 0;
}

header h1 {
  font-size: 22px;
  font-weight: 600;
  margin-right: auto;
}

#refresh-btn {
  background: transparent;
  color: var(--subtle-text-color);
  border: none;
  padding: 8px;
  border-radius: 50%;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease;
  font-size: 16px;
  line-height: 1;
}

#refresh-btn:hover {
  background-color: var(--border-color);
  color: var(--text-color);
}

#main-content {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

#messages {
  flex-grow: 1;
  overflow-y: auto;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

#messages::-webkit-scrollbar {
  width: 8px;
}

#messages::-webkit-scrollbar-track {
  background: transparent;
}

#messages::-webkit-scrollbar-thumb {
  background-color: var(--border-color);
  border-radius: 4px;
}

.message {
  display: flex;
  flex-direction: column;
  max-width: 75%;
  word-wrap: break-word;
}

.message-content {
  padding: 10px 16px;
  border-radius: 18px;
  line-height: 1.5;
}

.message-sender {
  font-size: 0.8em;
  color: var(--subtle-text-color);
  margin-bottom: 4px;
  padding: 0 8px;
}

.message.sent {
  align-self: flex-end;
  align-items: flex-end;
}

.message.received {
  align-self: flex-start;
  align-items: flex-start;
}

.message.sent .message-content {
  background-color: var(--primary-color);
  color: #fff;
  border-bottom-right-radius: 4px;
}

.message.received .message-content {
  background-color: #3a3a3c;
  color: var(--text-color);
  border-bottom-left-radius: 4px;
}

.message-appear-animation {
  animation: message-appear 0.3s ease-out forwards;
}

@keyframes message-appear {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

#chat-form {
  display: flex;
  padding: 16px 24px;
  border-top: 1px solid var(--border-color);
  gap: 16px;
  flex-shrink: 0;
}

#message-input {
  flex-grow: 1;
  background-color: #3a3a3c;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 12px 16px;
  color: var(--text-color);
  font-family: var(--font-family);
  font-size: 16px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

#message-input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(10, 132, 255, 0.3);
}

#chat-form button {
  background-color: var(--primary-color);
  color: #fff;
  border: none;
  padding: 12px 24px;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s ease;
  font-weight: 600;
  font-family: var(--font-family);
  font-size: 16px;
}

#chat-form button:hover {
  background-color: #0073e6;
}

/* Modal Styles */
.modal {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0,0,0,0.6);
  backdrop-filter: blur(5px);
}

.modal-content {
  background-color: var(--surface-color);
  margin: 15% auto;
  padding: 24px;
  border: 1px solid var(--border-color);
  width: 90%;
  max-width: 400px;
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.3);
  position: relative;
}

.close-btn {
  color: var(--subtle-text-color);
  position: absolute;
  top: 16px;
  right: 16px;
  font-size: 28px;
  font-weight: bold;
  cursor: pointer;
  transition: color 0.2s ease;
}

.close-btn:hover, .close-btn:focus {
  color: var(--text-color);
}

#user-info-form input {
  width: 100%;
  padding: 12px;
  margin-bottom: 16px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background-color: #3a3a3c;
  color: var(--text-color);
  font-family: var(--font-family);
  font-size: 16px;
}

#user-info-form input:focus {
  outline: none;
  border-color: var(--primary-color);
}

.modal-buttons {
  text-align: right;
}

.modal-buttons button {
  background-color: var(--primary-color);
  color: white;
  padding: 10px 20px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s ease;
  font-size: 16px;
  font-weight: 500;
}

.modal-buttons button:hover {
  background-color: #0073e6;
}