:root {
  --bg: #111318;
  --panel: #1a1d24;
  --panel-2: #20242c;
  --text: #e8e9ec;
  --text-dim: #9096a3;
  --border: #2a2e38;
  --accent: #6c8cff;
  --accent-text: #ffffff;
  --bubble-user: #6c8cff;
  --bubble-ai: #20242c;
  --radius: 14px;
}

[data-theme="light"] {
  --bg: #f4f5f7;
  --panel: #ffffff;
  --panel-2: #eef0f4;
  --text: #1c1e24;
  --text-dim: #6b7080;
  --border: #dfe2e8;
  --accent: #4468e5;
  --accent-text: #ffffff;
  --bubble-user: #4468e5;
  --bubble-ai: #eef0f4;
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

html, body {
  margin: 0;
  height: 100%;
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  overflow: hidden;
}

#bg-layer {
  position: fixed;
  inset: 0;
  z-index: 0;
  background-size: cover;
  background-position: center;
  opacity: 0;
  pointer-events: none;
}

.app {
  position: relative;
  z-index: 1;
  display: flex;
  height: 100vh;
  height: 100dvh;
}

/* Sidebar */
.sidebar {
  width: 240px;
  flex-shrink: 0;
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  backdrop-filter: blur(6px);
}

.sidebar-header { padding: 14px; }

.conversation-list {
  flex: 1;
  overflow-y: auto;
  padding: 0 8px;
}

.conversation-item {
  padding: 10px 12px;
  border-radius: 10px;
  cursor: pointer;
  color: var(--text-dim);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
}

.conversation-item:hover { background: var(--panel-2); }
.conversation-item.active { background: var(--accent); color: var(--accent-text); }
.conversation-item.active .delete-btn { color: var(--accent-text); }
.conversation-item.active .delete-btn:hover { background: rgba(255,255,255,0.2); }

.conversation-item .delete-btn {
  opacity: 0;
  color: var(--text-dim);
}
.conversation-item:hover .delete-btn { opacity: 0.7; }
.conversation-item .delete-btn:hover { opacity: 1; }

.sidebar-footer {
  padding: 12px;
  border-top: 1px solid var(--border);
}

/* Chat area */
.chat-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.chat-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--panel) 80%, transparent);
  backdrop-filter: blur(6px);
}

.menu-btn { display: none; }

.message-list {
  flex: 1;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.message-row {
  display: flex;
  gap: 10px;
  max-width: 80%;
}

.message-row.user { align-self: flex-end; flex-direction: row-reverse; }
.message-row.assistant { align-self: flex-start; }

.bubble {
  padding: 10px 14px;
  border-radius: var(--radius);
  line-height: 1.55;
  word-break: break-word;
}

.message-row.user .bubble { background: var(--bubble-user); color: var(--accent-text); border-top-right-radius: 4px; }
.message-row.assistant .bubble { background: var(--bubble-ai); border-top-left-radius: 4px; }

.bubble pre {
  background: #0d0f13;
  padding: 10px;
  border-radius: 8px;
  overflow-x: auto;
}
.bubble code { font-family: "Cascadia Code", Consolas, monospace; font-size: 0.9em; }
.bubble p { margin: 0.35em 0; }

.input-bar {
  display: flex;
  gap: 10px;
  padding: 14px 16px;
  padding-bottom: max(14px, env(safe-area-inset-bottom));
  border-top: 1px solid var(--border);
  background: color-mix(in srgb, var(--panel) 80%, transparent);
}

#input-box {
  flex: 1;
  resize: none;
  max-height: 160px;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-size: 16px;
  font-family: inherit;
}
#input-box:focus { outline: 2px solid var(--accent); }

/* Buttons */
.btn-primary, .btn-ghost, .icon-btn, .icon-label-btn {
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-size: 14px;
  font-family: inherit;
  transform: scale(1) translateZ(0);
  transition: transform 0.45s cubic-bezier(0.34, 1.56, 0.64, 1),
              background-color 0.15s ease,
              color 0.15s ease,
              filter 0.15s ease;
}
.btn-primary:active, .btn-ghost:active, .icon-btn:active, .icon-label-btn:active {
  transform: scale(0.93) translateZ(0);
  transition: transform 0.12s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-primary { background: var(--accent); color: var(--accent-text); width: 100%; padding: 9px 14px; }
.btn-primary:hover { filter: brightness(1.08); }

.btn-ghost { background: transparent; color: var(--text-dim); padding: 8px 14px; }
.btn-ghost:hover { color: var(--text); background: var(--panel-2); }

.icon-label-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.icon-label-btn svg { width: 16px; height: 16px; flex-shrink: 0; }

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: transparent;
  color: var(--text-dim);
  padding: 0;
  flex-shrink: 0;
}
.icon-btn svg { width: 18px; height: 18px; }
.icon-btn:hover { color: var(--text); background: var(--panel-2); }
.icon-btn.icon-btn-sm { width: 26px; height: 26px; }
.icon-btn.icon-btn-sm svg { width: 14px; height: 14px; }
.icon-btn.icon-btn-danger:hover { color: #e05a5a; background: rgba(224, 90, 90, 0.14); }

.send-btn {
  width: 40px;
  height: 40px;
  background: var(--accent);
  color: var(--accent-text);
}
.send-btn:hover { filter: brightness(1.1); background: var(--accent); color: var(--accent-text); }
.send-btn svg { width: 17px; height: 17px; }

.model-select {
  padding: 6px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  min-width: 0;
}

/* Avatars */
.avatar { border-radius: 50%; object-fit: cover; background: var(--panel-2); }
.avatar-sm { width: 26px; height: 26px; }
.avatar-md { width: 56px; height: 56px; }
.avatar-chat { width: 30px; height: 30px; flex-shrink: 0; margin-top: 2px; }

/* Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
}
.modal-overlay.hidden { display: none; }

.modal {
  width: 520px;
  max-height: 80vh;
  overflow-y: auto;
  background: var(--panel);
  border-radius: 16px;
  border: 1px solid var(--border);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
}
.modal-header h2 { margin: 0; font-size: 18px; }

.modal-body { padding: 16px 20px; display: flex; flex-direction: column; gap: 22px; }
.settings-section h3 { margin: 0 0 10px; font-size: 14px; color: var(--text-dim); }

.theme-toggle, .bg-row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }

.avatar-row { display: flex; gap: 20px; }
.avatar-pick { display: flex; flex-direction: column; align-items: center; gap: 8px; }

.opacity-label { display: flex; flex-direction: column; gap: 4px; font-size: 12px; color: var(--text-dim); }

.provider-card {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  margin-bottom: 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.provider-card-row { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.provider-card input, .provider-card select {
  flex: 1;
  min-width: 100px;
  padding: 6px 8px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-size: 13px;
}
.provider-card .remove-btn {
  color: var(--text-dim);
  background: transparent;
  border: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  flex-shrink: 0;
  transform: scale(1);
  transition: transform 0.45s cubic-bezier(0.34, 1.56, 0.64, 1), color 0.15s ease, background-color 0.15s ease;
}
.provider-card .remove-btn svg { width: 14px; height: 14px; }
.provider-card .remove-btn:hover { color: #e05a5a; background: rgba(224, 90, 90, 0.14); }
.provider-card .remove-btn:active {
  transform: scale(0.85);
  transition: transform 0.12s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Sidebar overlay (mobile drawer scrim) */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.45);
  z-index: 5;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}
.sidebar-overlay.visible { opacity: 1; pointer-events: auto; }

/* ---- Responsive: tablet / mobile ---- */
@media (max-width: 768px) {
  .menu-btn { display: inline-flex; }

  .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 6;
    width: min(78vw, 300px);
    transform: translateX(-100%);
    transition: transform 0.3s cubic-bezier(0.32, 0.72, 0, 1);
    box-shadow: 8px 0 24px rgba(0,0,0,0.25);
  }
  .sidebar.sidebar-open { transform: translateX(0); }

  .sidebar-overlay { display: block; }

  .chat-header { padding: 10px 12px; gap: 8px; }
  .model-select { font-size: 13px; padding: 6px 8px; }

  .message-list { padding: 14px; gap: 12px; }
  .message-row { max-width: 92%; }

  .input-bar { padding: 10px 12px; padding-bottom: max(10px, env(safe-area-inset-bottom)); }

  .icon-btn { width: 40px; height: 40px; }
  .icon-btn svg { width: 20px; height: 20px; }
  .icon-btn.icon-btn-sm { width: 34px; height: 34px; }
  .icon-btn.icon-btn-sm svg { width: 16px; height: 16px; }
  .send-btn { width: 44px; height: 44px; }

  .modal-overlay { align-items: flex-end; }
  .modal {
    width: 100%;
    max-width: 100%;
    max-height: 88vh;
    border-radius: 20px 20px 0 0;
  }

  .avatar-row { justify-content: space-around; }
}

@media (max-width: 420px) {
  .modal-body { padding: 14px; gap: 18px; }
  .provider-card-row { flex-direction: column; align-items: stretch; }
  .provider-card .remove-btn { align-self: flex-end; }
}