.app-container { display: grid; grid-template-columns: var(--sidebar-width) 1fr; height: 100vh; transition: grid-template-columns 0.28s ease; }
.app-container.sidebar-collapsed { grid-template-columns: 0px 1fr; }

/* 左边栏 — 玻璃 */
.sidebar {
  background: rgba(255,255,255,.5); backdrop-filter: blur(24px); -webkit-backdrop-filter: blur(24px);
  border-right: 1px solid rgba(255,255,255,.7); box-shadow: 0 0 30px rgba(255,255,255,.4);
  display: flex; flex-direction: column;
  overflow: hidden; transition: all 0.28s ease;
}
.app-container.sidebar-collapsed .sidebar { border-right: none; }
.sidebar-header {
  padding: 14px 16px; border-bottom: var(--border-light);
  font-weight: 600; color: var(--text-2); font-size: 12px;
  flex-shrink: 0; display: flex; align-items: center; gap: 6px;
}
.session-list { flex: 1; overflow-y: auto; padding: 8px 10px; }

/* 主区域 — 极简 */
.main-area {
  display: flex; flex-direction: column;
  background: transparent; max-width: 960px; margin: 0 auto;
  width: 100%; height: 100vh; overflow: hidden;
}

.top-bar { display: flex; justify-content: space-between; align-items: center; padding: 14px 20px 0; flex-shrink: 0; }
.top-bar-left { display: flex; align-items: center; gap: 6px; }
.top-bar-center { text-align: center; flex: 1; }
.top-bar-center h1 { font-size: 16px; font-weight: 600; letter-spacing: 2px; color: var(--text-1); }
.top-bar-center .subtitle { font-size: var(--fs-micro); color: var(--text-3); margin-top: 1px; font-weight: 500; }

.phase-indicator { display: flex; justify-content: center; gap: 4px; padding: 10px 20px 0; flex-shrink: 0; }
.phase-dot { width: 6px; height: 6px; border-radius: 50%; background: rgba(147,170,197,.25); transition: all 0.3s; }
.phase-dot.active { background: var(--accent); box-shadow: 0 0 6px rgba(143,182,217,.4); width: 8px; height: 8px; margin-top: -1px; }
.phase-dot.done { background: var(--ok); }

.chat-area { flex: 1; overflow-y: auto; padding: 16px 20px; display: flex; flex-direction: column; gap: var(--gap); min-height: 0; }

/* 输入区 — 居中窄框，可拖拽展开 */
.input-area {
  padding: 12px 20px 16px;
  flex-shrink: 0; display: flex; justify-content: center;
}
.input-wrapper {
  display: flex; gap: 6px;
  background: var(--surface); border: var(--border); border-radius: var(--r-pill);
  padding: 5px 5px 5px 16px; align-items: center;
  box-shadow: var(--shadow-soft); max-width: 520px; width: 100%;
}
.input-wrapper textarea {
  flex: 1; background: transparent; border: none; resize: none;
  font-family: var(--font-serif); font-size: var(--fs-body);
  color: var(--text-1); outline: none;
  min-height: 20px; max-height: 200px; line-height: 1.5; overflow-y: auto;
  padding: 3px 0;
}