/* ═══════════════════════════════════════
   顶部栏 + 模型选择器 + 步骤进度
   ═══════════════════════════════════════ */

.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: center;
  padding: 14px 24px;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
}

.topbar-inner {
  display: flex; align-items: center; gap: 14px;
  width: 100%; max-width: var(--max-w);
}

.brand-mark {
  display: grid; width: 40px; height: 40px;
  place-items: center; color: #fff;
  background: linear-gradient(135deg, var(--brand), var(--brand-dark));
  border-radius: 10px; flex-shrink: 0;
}

.brand-mark svg { width: 22px; height: 22px; }
.brand-name { margin: 0; font-size: 16px; font-weight: 800; }
.brand-note { margin: 0; color: var(--muted); font-size: 12px; }

.topbar-spacer { flex: 1; }

/* ── 模型选择器 ── */
.model-picker {
  display: flex; align-items: center; gap: 8px;
  padding: 6px 10px 6px 14px;
  background: #f8fafc;
  border: 1.5px solid var(--line);
  border-radius: 10px;
  transition: all 0.2s;
}
.model-picker:hover { border-color: #cbd5e1; background: #fff; }
.model-picker-label {
  font-size: 12px; font-weight: 700;
  color: var(--muted);
  display: flex; align-items: center; gap: 4px;
}
.model-picker-label svg { width: 14px; height: 14px; }
.model-picker select {
  height: 34px; width: auto;
  padding: 0 28px 0 10px;
  border: 1.5px solid var(--line);
  border-radius: 7px;
  background: #fff;
  font-size: 13px; font-weight: 600;
  color: var(--ink);
  appearance: none;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2'><path d='M6 9l6 6 6-6'/></svg>");
  background-repeat: no-repeat;
  background-position: right 8px center;
  cursor: pointer;
}
.model-picker select:focus { border-color: var(--brand); box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.15); }

/* ── 步骤进度 ── */
.step-bar {
  display: flex; align-items: center; justify-content: center;
  gap: 0; padding: 28px 24px 20px;
}

.step-bar-inner {
  display: flex; align-items: center; gap: 0;
  max-width: 820px; width: 100%;
}

.step-node {
  display: flex; align-items: center; gap: 10px;
  white-space: nowrap;
}

.step-num {
  display: grid; width: 36px; height: 36px;
  place-items: center; font-size: 15px; font-weight: 800;
  border-radius: 50%; border: 2px solid var(--line);
  color: var(--muted); background: #fff;
  transition: all 0.3s;
}

.step-node.active .step-num {
  color: #fff; background: var(--brand);
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-light);
}
.step-node.done .step-num {
  color: #fff; background: var(--brand);
  border-color: var(--brand);
}

.step-label {
  font-size: 14px; font-weight: 600;
  color: var(--muted); transition: color 0.3s;
}
.step-node.active .step-label,
.step-node.done .step-label { color: var(--ink); }

.step-line {
  flex: 1; height: 2px; margin: 0 12px;
  background: var(--line); transition: background 0.3s;
}
.step-line.done { background: var(--brand); }

@media (max-width: 760px) {
  .topbar { padding: 10px 14px; flex-wrap: wrap; }
  .brand-note { display: none; }
  .model-picker-label span { display: none; }
  .step-bar { padding: 20px 16px 14px; }
  .step-label { display: none; }
  .step-line { margin: 0 8px; }
}