:root {
  --bg-page: #0a0e17;
  --bg-surface: #121826;
  --bg-card: #182032;
  --bg-hover: #1e293f;
  --border-subtle: #243048;
  --border-focus: #38bdf8;
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --text-subtle: #64748b;
  --accent-blue: #38bdf8;
  --accent-green: #34d399;
  --accent-purple: #c084fc;
  --accent-danger: #f87171;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --font-mono: "JetBrains Mono", monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  background-color: var(--bg-page);
  color: var(--text-main);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Header */
.app-header {
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0.65rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-shrink: 0;
}
.header-left { display: flex; align-items: center; gap: 0.75rem; }
.logo-icon { font-size: 1.4rem; }
.brand-title { font-weight: 700; font-size: 1.15rem; }
.brand-badge {
  background-color: rgba(56, 189, 248, 0.15);
  color: var(--accent-blue);
  border: 1px solid rgba(56, 189, 248, 0.3);
  font-size: 0.75rem;
  padding: 0.15rem 0.45rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
}

.header-right { display: flex; align-items: center; gap: 1rem; }
.user-select-box {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.user-select-box input {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-main);
  padding: 0.3rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  width: 100px;
  outline: none;
}
.user-select-box input:focus { border-color: var(--border-focus); }

.lang-switcher {
  display: flex;
  background-color: var(--bg-card);
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--border-subtle);
}
.btn-lang {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 0.25rem 0.55rem;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
}
.btn-lang.active { background-color: var(--accent-blue); color: #000; }

/* Layout */
.chat-container {
  display: flex;
  flex: 1;
  overflow: hidden;
}

/* Sidebar */
.sidebar-channels {
  width: 250px;
  background-color: var(--bg-surface);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  padding: 1rem 0.75rem;
  overflow-y: auto;
  flex-shrink: 0;
}
.sidebar-section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 0.5rem 0.4rem;
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text-subtle);
  letter-spacing: 0.05em;
}
.btn-add {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
  padding: 0 0.2rem;
}
.btn-add:hover { color: var(--text-main); }

.channel-list {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}
.channel-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  border: none;
  background: transparent;
  width: 100%;
  text-align: left;
  transition: all 0.15s ease;
}
.channel-item:hover {
  background-color: var(--bg-hover);
  color: var(--text-main);
}
.channel-item.active {
  background-color: rgba(56, 189, 248, 0.12);
  color: var(--accent-blue);
  font-weight: 600;
}
.channel-prefix { font-weight: 700; color: var(--text-subtle); }
.channel-item.active .channel-prefix { color: var(--accent-blue); }

.online-users-list {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  margin-top: 0.3rem;
}
.user-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  color: var(--text-muted);
}
.status-indicator {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent-green);
  box-shadow: 0 0 6px var(--accent-green);
}
.badge {
  background-color: var(--bg-card);
  color: var(--accent-blue);
  font-size: 0.7rem;
  font-weight: 700;
  padding: 0.1rem 0.4rem;
  border-radius: 10px;
}

/* Chat Main Area */
.chat-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-page);
  overflow: hidden;
}

.chat-header {
  padding: 0.85rem 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
  background-color: var(--bg-surface);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-shrink: 0;
}
.channel-info h2 {
  font-size: 1.15rem;
  font-weight: 700;
}
.channel-topic {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}

.connection-status {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}
.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent-green);
}
.connection-status.disconnected .status-dot {
  background-color: var(--accent-danger);
}

/* Message Stream */
.message-stream {
  flex: 1;
  padding: 1.25rem 1.5rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.message-row {
  display: flex;
  gap: 0.85rem;
  align-items: flex-start;
}
.avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 0.85rem;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}
.message-content {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  max-width: 85%;
}
.message-meta {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}
.sender-name {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--text-main);
}
.msg-timestamp {
  font-size: 0.72rem;
  color: var(--text-subtle);
}
.msg-text {
  font-size: 0.92rem;
  line-height: 1.45;
  color: #e2e8f0;
  word-break: break-word;
  white-space: pre-wrap;
}

/* Chat Input */
.chat-input-container {
  padding: 1rem 1.5rem;
  background-color: var(--bg-surface);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  gap: 0.75rem;
  flex-shrink: 0;
}
.chat-input-container input {
  flex: 1;
  background-color: var(--bg-page);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  color: var(--text-main);
  padding: 0.75rem 1rem;
  font-size: 0.95rem;
  outline: none;
}
.chat-input-container input:focus { border-color: var(--border-focus); }

.btn {
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.6rem 1.1rem;
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.15s ease;
}
.btn-primary {
  background-color: var(--accent-blue);
  color: #000;
}
.btn-primary:hover { background-color: #0284c7; color: #fff; }
.btn-secondary {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  color: var(--text-main);
}
.btn-secondary:hover { background-color: var(--bg-hover); }

/* Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(4px);
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 1rem;
  z-index: 1000;
}
.modal-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 480px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
}
.modal-header h3 { font-size: 1.15rem; font-weight: 700; }
.btn-close {
  background: transparent;
  border: none;
  color: var(--text-subtle);
  font-size: 1.5rem;
  cursor: pointer;
  line-height: 1;
}
.btn-close:hover { color: var(--text-main); }
.modal-body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.form-group label {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
}
.form-group input {
  background-color: var(--bg-page);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  padding: 0.6rem 0.75rem;
  font-size: 0.9rem;
  outline: none;
}
.form-group input:focus { border-color: var(--border-focus); }
.input-with-prefix {
  display: flex;
  align-items: center;
  background-color: var(--bg-page);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding-left: 0.75rem;
}
.input-with-prefix .prefix {
  font-weight: 700;
  color: var(--accent-blue);
}
.input-with-prefix input {
  border: none;
  background: transparent;
  width: 100%;
}
.modal-footer {
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
  margin-top: 0.5rem;
}