:root {
  --bg-dark: #0f172a;
  --bg-sidebar: #1e293b;
  --bg-card: #1e293b;
  --bg-input: #1e293b;
  --border-color: #334155;
  --accent-color: #6366f1;
  --accent-hover: #4f46e5;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-green: #10b981;
  --text-amber: #f59e0b;
  --text-red: #ef4444;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'Fira Code', monospace;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-main);
  height: 100vh;
  overflow: hidden;
}

.app-layout {
  display: flex;
  height: 100vh;
  width: 100vw;
  position: relative;
}

/* Sidebar Backdrop for Mobile */
.sidebar-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.75);
  backdrop-filter: blur(4px);
  z-index: 90;
}

.sidebar-backdrop.open {
  display: block;
}

/* Sidebar */
.sidebar {
  width: 280px;
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  padding: 1rem;
  gap: 1.25rem;
  z-index: 100;
  transition: transform 0.25s ease;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brand-icon {
  width: 34px;
  height: 34px;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
}

.brand-name {
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
}

.new-chat-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.75rem;
  background-color: rgba(99, 102, 241, 0.15);
  color: #818cf8;
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.new-chat-btn:hover {
  background-color: var(--accent-color);
  color: white;
  border-color: var(--accent-color);
}

.sidebar-section {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.section-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  font-weight: 600;
}

/* Select wrapper */
.select-wrapper {
  position: relative;
}

.sidebar-select {
  width: 100%;
  padding: 0.6rem;
  background-color: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-main);
  font-size: 0.85rem;
  font-family: var(--font-sans);
  outline: none;
  cursor: pointer;
}

.sidebar-select:focus {
  border-color: var(--accent-color);
}

/* Mode Selector Grid */
.mode-selector {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.mode-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.25rem;
  padding: 0.6rem 0.4rem;
  background-color: rgba(15, 23, 42, 0.4);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.mode-btn:hover {
  background-color: rgba(99, 102, 241, 0.1);
  color: var(--text-main);
}

.mode-btn.active {
  background-color: rgba(99, 102, 241, 0.2);
  border-color: var(--accent-color);
  color: #a5b4fc;
}

.mode-icon {
  font-size: 1rem;
}

/* Collapsible System Prompt */
.collapsible .section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
}

.collapsible .chevron {
  transition: transform 0.2s ease;
  color: var(--text-muted);
}

.collapsible.open .chevron {
  transform: rotate(180deg);
}

.system-prompt-body {
  display: none;
  margin-top: 0.5rem;
}

.collapsible.open .system-prompt-body {
  display: block;
}

#systemPromptInput {
  width: 100%;
  height: 100px;
  background-color: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-main);
  padding: 0.5rem;
  font-size: 0.8rem;
  font-family: var(--font-sans);
  resize: vertical;
  outline: none;
}

#systemPromptInput:focus {
  border-color: var(--accent-color);
}

.sidebar-footer {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  border-top: 1px solid var(--border-color);
  padding-top: 0.75rem;
}

.status-meta {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
}

.meta-label {
  color: var(--text-muted);
}

.text-green {
  color: var(--text-green);
}

.version-tag {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-align: center;
}

/* Main Chat */
.chat-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  height: 100vh;
  background-color: var(--bg-dark);
  position: relative;
}

.chat-header {
  height: 60px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  background-color: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(8px);
}

.header-title {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.header-title h2 {
  font-size: 1rem;
  font-weight: 600;
}

.active-mode-badge {
  font-size: 0.75rem;
  padding: 0.2rem 0.6rem;
  background-color: rgba(99, 102, 241, 0.2);
  border: 1px solid rgba(99, 102, 241, 0.4);
  color: #a5b4fc;
  border-radius: 12px;
  font-weight: 500;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
}

.icon-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.4rem;
  border-radius: 6px;
  transition: all 0.2s ease;
}

.icon-btn:hover {
  background-color: var(--border-color);
  color: var(--text-main);
}

/* Messages Container */
.messages-container {
  flex: 1;
  overflow-y: auto;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Welcome Banner */
.welcome-banner {
  margin: auto;
  max-width: 600px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  padding: 2rem;
}

.welcome-icon {
  font-size: 2.5rem;
  background: rgba(99, 102, 241, 0.15);
  width: 64px;
  height: 64px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.welcome-banner h1 {
  font-size: 1.5rem;
  font-weight: 700;
}

.welcome-banner p {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.5;
}

.prompt-chips {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  margin-top: 1rem;
}

.chip {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 0.5rem 0.85rem;
  border-radius: 20px;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.chip:hover {
  border-color: var(--accent-color);
  background-color: rgba(99, 102, 241, 0.15);
}

/* Message Rows */
.message-row {
  display: flex;
  gap: 1rem;
  max-width: 850px;
  width: 100%;
  margin: 0 auto;
}

.message-row.user {
  flex-direction: row-reverse;
}

.avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: #3b82f6;
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.85rem;
  flex-shrink: 0;
}

.message-row.assistant .avatar {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
}

.message-content {
  flex: 1;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  padding: 1rem;
  border-radius: 12px;
  line-height: 1.6;
  font-size: 0.95rem;
  overflow-x: auto;
}

.message-row.user .message-content {
  background-color: rgba(99, 102, 241, 0.15);
  border-color: rgba(99, 102, 241, 0.3);
}

/* Reasoning Collapsible Block */
.reasoning-block {
  background: rgba(15, 23, 42, 0.5);
  border: 1px solid #334155;
  border-radius: 8px;
  margin-bottom: 0.75rem;
  overflow: hidden;
}

.reasoning-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0.75rem;
  background: rgba(30, 41, 59, 0.7);
  cursor: pointer;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.reasoning-header:hover {
  color: var(--text-main);
}

.reasoning-body {
  padding: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: #cbd5e1;
  background: rgba(15, 23, 42, 0.7);
  white-space: pre-wrap;
  max-height: 250px;
  overflow-y: auto;
  border-top: 1px solid #334155;
}

.reasoning-block.collapsed .reasoning-body {
  display: none;
}

/* Tool Execution Cards */
.tool-card {
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.5rem 0.75rem;
  margin-bottom: 0.5rem;
  font-size: 0.8rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.tool-card.running {
  border-color: var(--accent-color);
}

.tool-card.done {
  border-color: var(--text-green);
}

.tool-card.error {
  border-color: var(--text-red);
}

.tool-info {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.tool-badge {
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  background: #334155;
  color: #a5b4fc;
}

/* Sources Container */
.sources-container {
  margin-top: 0.75rem;
  padding-top: 0.5rem;
  border-top: 1px dashed var(--border-color);
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  align-items: center;
}

.sources-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
}

.source-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.2rem 0.5rem;
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  font-size: 0.75rem;
  color: #818cf8;
  text-decoration: none;
  transition: all 0.2s ease;
}

.source-chip:hover {
  border-color: var(--accent-color);
  background: rgba(99, 102, 241, 0.15);
}

/* Code Block Formatting & Copy Button */
.code-block-wrapper {
  position: relative;
  margin: 0.75rem 0;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border-color);
}

.code-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.4rem 0.75rem;
  background-color: #1e293b;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}

.copy-code-btn {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.75rem;
}

.copy-code-btn:hover {
  color: var(--text-main);
}

pre code {
  font-family: var(--font-mono);
  padding: 0.75rem !important;
  font-size: 0.85rem;
  display: block;
}

/* Input Form */
.input-area {
  padding: 1rem 1.5rem;
  background-color: var(--bg-dark);
}

.input-form {
  max-width: 850px;
  margin: 0 auto;
}

.textarea-wrapper {
  display: flex;
  align-items: flex-end;
  background-color: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 0.75rem;
  gap: 0.75rem;
}

.textarea-wrapper:focus-within {
  border-color: var(--accent-color);
}

#userPrompt {
  flex: 1;
  background: none;
  border: none;
  color: var(--text-main);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  outline: none;
  resize: none;
  max-height: 200px;
}

.action-buttons {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.send-btn, .stop-btn {
  background-color: var(--accent-color);
  color: white;
  border: none;
  width: 36px;
  height: 36px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s ease;
  flex-shrink: 0;
}

.stop-btn {
  width: auto;
  padding: 0 0.75rem;
  gap: 0.3rem;
  background-color: var(--text-red);
  font-size: 0.8rem;
  font-weight: 500;
}

.send-btn:disabled {
  background-color: var(--border-color);
  color: var(--text-muted);
  cursor: not-allowed;
}

.send-btn:not(:disabled):hover {
  background-color: var(--accent-hover);
}

.input-footer {
  text-align: center;
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
}

/* Streaming Cursor Effect */
.streaming-cursor::after {
  content: '▋';
  display: inline-block;
  vertical-align: baseline;
  animation: blink 1s infinite;
  color: var(--accent-color);
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

/* Responsive */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    transform: translateX(-100%);
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .mobile-toggle {
    display: block;
  }
}