/* ===== layout.css —— 主容器、品牌区与背景 ===== */

.nav-container {
  position: relative;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  /* 无 background.jpg 时使用的科技感壁纸（放置真实图片后可改回 url()） */
  background:
    radial-gradient(1200px 800px at 50% 32%, rgba(0, 90, 150, 0.28), transparent 60%),
    radial-gradient(900px 700px at 82% 82%, rgba(0, 40, 90, 0.22), transparent 60%),
    var(--bg);
}

/* HUD 网格底纹 */
.nav-container::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0, 243, 255, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 243, 255, 0.05) 1px, transparent 1px);
  background-size: 48px 48px;
  -webkit-mask-image: radial-gradient(circle at 50% 44%, #000 28%, transparent 82%);
  mask-image: radial-gradient(circle at 50% 44%, #000 28%, transparent 82%);
  pointer-events: none;
}

/* 顶部品牌区：logo 钉在左上 */
.brand-header {
  position: absolute;
  top: 1.8%;
  left: 1.6%;
  width: 34%;
  height: 8.5%;
  z-index: 40;
  pointer-events: none;
  display: flex;
  align-items: center;
  gap: 14px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  height: 100%;
}

.brand-logo img {
  display: block;
  height: 100%;
  width: auto;
  max-width: 100%;
  object-fit: contain;
  object-position: left center;
  mix-blend-mode: screen;
  filter: drop-shadow(0 0 8px rgba(0, 243, 255, 0.28));
}

/* 无图时的文字 logo 占位 */
.brand-logo .logo-mark {
  width: 34px;
  height: 34px;
  border: 1.5px solid var(--accent);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  font-weight: 800;
  font-size: 14px;
  letter-spacing: 1px;
  box-shadow: inset 0 0 10px var(--accent-faint), 0 0 12px var(--accent-soft);
}

.brand-logo .logo-text {
  color: var(--text-strong);
  font-family: var(--font-cn);
  font-size: 1vw;
  font-weight: 700;
  letter-spacing: 1px;
  text-shadow: 0 0 10px rgba(0, 243, 255, 0.5);
  white-space: nowrap;
}

/* 主标题：顶部居中 */
.brand-title {
  position: absolute;
  left: 50%;
  top: 12.8%;
  transform: translate(-50%, -50%);
  z-index: 40;
  pointer-events: none;
  color: var(--text-strong);
  font-family: var(--font-cn);
  font-size: 2.15vw;
  font-weight: 800;
  letter-spacing: 0.18vw;
  line-height: 1.25;
  white-space: nowrap;
  text-align: center;
  text-shadow:
    0 0 16px rgba(0, 243, 255, 0.7),
    0 2px 12px rgba(0, 0, 0, 0.8);
}

/* 左下角演示控制条（用于独立验证自动讲解） */
.portal-controls {
  position: fixed;
  left: 18px;
  bottom: 18px;
  z-index: 60;
  display: flex;
  gap: 10px;
}

.portal-controls button {
  cursor: pointer;
  color: var(--accent);
  background: rgba(0, 30, 80, 0.4);
  border: 1px solid var(--accent-soft);
  padding: 8px 16px;
  font-size: 13px;
  letter-spacing: 2px;
  border-radius: 6px;
  box-shadow: inset 0 0 10px var(--accent-faint);
  transition: all 0.2s ease;
}

.portal-controls button:hover {
  background: rgba(0, 243, 255, 0.16);
  box-shadow: 0 0 12px rgba(0, 243, 255, 0.35);
}