/* ============================================================
   CSS Custom Properties
   ============================================================ */
:root {
  --color-bg: #f0f2f5;
  --color-surface: #ffffff;
  --color-border: #d1d5db;
  --color-text: #111827;
  --color-text-muted: #6b7280;
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-text: #ffffff;

  /* Chat bubbles */
  --bubble-user-bg: #2563eb;
  --bubble-user-text: #ffffff;
  --bubble-assistant-bg: #e5e7eb;
  --bubble-assistant-text: #111827;

  /* Error */
  --color-error-bg: #dc2626;
  --color-error-text: #ffffff;

  /* Layout */
  --config-panel-transition: 0.2s ease;
  --border-radius-sm: 6px;
  --border-radius-md: 12px;
  --border-radius-lg: 18px;

  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
}

/* ============================================================
   Reset & Base
   ============================================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  height: 100%;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  font-size: 15px;
  line-height: 1.5;
  color: var(--color-text);
  background: var(--color-bg);
}

/* ============================================================
   Accessibility — Focus Styles
   ============================================================ */
:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

/* ============================================================
   Error Banner
   ============================================================ */
#error-banner {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-md);
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--color-error-bg);
  color: var(--color-error-text);
  font-size: 0.9rem;
  font-weight: 500;
}

#error-banner[hidden] {
  display: none;
}

#error-close {
  flex-shrink: 0;
  background: transparent;
  border: none;
  color: var(--color-error-text);
  font-size: 1.25rem;
  line-height: 1;
  cursor: pointer;
  padding: 2px 6px;
  border-radius: var(--border-radius-sm);
  opacity: 0.8;
  transition: opacity 0.15s;
}

#error-close:hover {
  opacity: 1;
}

#error-close:focus-visible {
  outline: 3px solid rgba(255, 255, 255, 0.7);
  outline-offset: 2px;
}

/* ============================================================
   App Layout — Three-row flex column
   ============================================================ */
.app-layout {
  display: flex;
  flex-direction: column;
  height: 100vh;
  max-width: 900px;
  margin: 0 auto;
  background: var(--color-surface);
  box-shadow: 0 0 0 1px var(--color-border);
}

/* ============================================================
   Config Header / Panel
   ============================================================ */
.config-header {
  flex-shrink: 0;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
}

.config-toggle {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  background: transparent;
  border: none;
  border-bottom: 1px solid transparent;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-muted);
  cursor: pointer;
  text-align: left;
  transition: background 0.15s, color 0.15s;
}

.config-toggle:hover {
  background: var(--color-bg);
  color: var(--color-text);
}

.toggle-arrow {
  margin-left: auto;
  font-size: 0.75rem;
  transition: transform var(--config-panel-transition);
}

.config-toggle[aria-expanded="false"] .toggle-arrow {
  transform: rotate(180deg);
}

/* Collapsed state */
.config-toggle[aria-expanded="false"] + .config-panel {
  display: none;
}

.config-panel {
  padding: var(--spacing-md);
  border-top: 1px solid var(--color-border);
}

.config-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-sm) var(--spacing-md);
}

.config-field {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.config-field--full {
  grid-column: 1 / -1;
}

.config-field--inline {
  justify-content: flex-end;
}

.config-field label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.config-field input[type="url"],
.config-field input[type="password"],
.config-field input[type="text"],
.config-field select,
.config-field textarea {
  padding: 7px 10px;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-sm);
  font-size: 0.9rem;
  font-family: inherit;
  color: var(--color-text);
  background: var(--color-surface);
  transition: border-color 0.15s;
  width: 100%;
}

.config-field input:hover,
.config-field select:hover,
.config-field textarea:hover {
  border-color: var(--color-primary);
}

.config-field input:focus,
.config-field select:focus,
.config-field textarea:focus {
  border-color: var(--color-primary);
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.config-field textarea {
  resize: vertical;
  min-height: 52px;
}

/* Streaming toggle */
.toggle-label {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  user-select: none;
  text-transform: none;
  letter-spacing: normal;
}

.toggle-label input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--color-primary);
  cursor: pointer;
}

/* ============================================================
   Messages Area
   ============================================================ */
.messages-wrapper {
  flex: 1;
  overflow-y: auto;
  background: var(--color-bg);
  padding: var(--spacing-md);
  scroll-behavior: smooth;
}

.messages {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  max-width: 100%;
}

/* Individual message rows */
.message {
  display: flex;
  flex-direction: column;
  max-width: 72%;
  animation: message-in 0.15s ease;
}

@keyframes message-in {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* User messages — right aligned */
.message--user {
  align-self: flex-end;
  align-items: flex-end;
}

/* Assistant messages — left aligned */
.message--assistant {
  align-self: flex-start;
  align-items: flex-start;
}

.message__role {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  margin-bottom: 3px;
}

.message__bubble {
  padding: 10px 14px;
  border-radius: var(--border-radius-lg);
  font-size: 0.95rem;
  line-height: 1.55;
  white-space: pre-wrap;
  word-break: break-word;
}

.message--user .message__bubble {
  background: var(--bubble-user-bg);
  color: var(--bubble-user-text);
  border-bottom-right-radius: var(--border-radius-sm);
}

.message--assistant .message__bubble {
  background: var(--bubble-assistant-bg);
  color: var(--bubble-assistant-text);
  border-bottom-left-radius: var(--border-radius-sm);
}

/* Streaming indicator — animated dots */
.streaming-indicator {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 10px 16px;
  background: var(--bubble-assistant-bg);
  border-radius: var(--border-radius-lg);
  border-bottom-left-radius: var(--border-radius-sm);
}

.streaming-indicator__dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-text-muted);
  animation: bounce 1.2s infinite ease-in-out;
}

.streaming-indicator__dot:nth-child(2) {
  animation-delay: 0.2s;
}

.streaming-indicator__dot:nth-child(3) {
  animation-delay: 0.4s;
}

@keyframes bounce {
  0%, 60%, 100% {
    transform: translateY(0);
    opacity: 0.5;
  }
  30% {
    transform: translateY(-6px);
    opacity: 1;
  }
}

/* Empty state */
.messages-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  min-height: 200px;
  gap: var(--spacing-sm);
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.messages-empty__icon {
  font-size: 2.5rem;
  opacity: 0.4;
}

/* ============================================================
   Input Area
   ============================================================ */
.input-area {
  flex-shrink: 0;
  padding: var(--spacing-sm) var(--spacing-md) var(--spacing-md);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}

.input-row {
  display: flex;
  gap: var(--spacing-sm);
  align-items: flex-end;
}

.message-input {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-md);
  font-family: inherit;
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--color-text);
  background: var(--color-surface);
  resize: none;
  max-height: 200px;
  overflow-y: auto;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.message-input:hover {
  border-color: var(--color-primary);
}

.message-input:focus {
  border-color: var(--color-primary);
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.message-input::placeholder {
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

.send-btn {
  flex-shrink: 0;
  padding: 10px 20px;
  background: var(--color-primary);
  color: var(--color-primary-text);
  border: none;
  border-radius: var(--border-radius-md);
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
  white-space: nowrap;
}

.send-btn:hover {
  background: var(--color-primary-hover);
}

.send-btn:active {
  opacity: 0.85;
}

.send-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.input-meta {
  display: flex;
  justify-content: flex-end;
  margin-top: 4px;
}

.char-count {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

.char-count--warn {
  color: #d97706;
}

.char-count--error {
  color: var(--color-error-bg);
  font-weight: 600;
}

/* ============================================================
   Scrollbar Styling (webkit)
   ============================================================ */
.messages-wrapper::-webkit-scrollbar {
  width: 6px;
}

.messages-wrapper::-webkit-scrollbar-track {
  background: transparent;
}

.messages-wrapper::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 3px;
}

.messages-wrapper::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-muted);
}

/* ============================================================
   Responsive — Mobile
   ============================================================ */
@media (max-width: 600px) {
  .config-grid {
    grid-template-columns: 1fr;
  }

  .config-field--full {
    grid-column: 1;
  }

  .message {
    max-width: 88%;
  }

  .app-layout {
    box-shadow: none;
  }
}

@media (max-width: 400px) {
  .message {
    max-width: 95%;
  }

  .send-btn {
    padding: 10px 14px;
  }
}