/* 竖屏自然阅读会把原舞台外的近黑衬底展开成长页面；沿用首页拼贴的深蓝色阶，只补背景，不参与布局和动效。 */
@media screen and (orientation:portrait) {
  html[data-theme="navy"] #site-viewport #page-content > .composition-hero {
    background:radial-gradient(ellipse at 82% 28%,#1a46984d,transparent 70%),linear-gradient(155deg,#061328,#0b254f 58%,#081c3c);
  }

  /* 原光区偏右且暗端接近纯黑，窄屏纵向展开后正文底部缺少环境光；两处柔光分别承接设备与下方介绍。 */
  html[data-theme="navy"] #site-viewport #page-content > #product-families .home-services-surface {
    background:radial-gradient(ellipse at 80% 24%,#0b33738c,transparent 67%),radial-gradient(ellipse at 16% 80%,#1a469840,transparent 70%),linear-gradient(155deg,#061328,#0b2b5b 56%,#081c3c);
  }

  /* 四项工程在阅读模式下可超过五千像素；光区按有限高度平滑重复，首尾同色，避免渐变拉满整页后只亮一处或形成硬接缝。 */
  html[data-theme="navy"] #site-viewport #page-content > #composition-story[data-flow-mode="reading"] {
    background-color:#061328;
    background-image:radial-gradient(ellipse 90% 42% at 88% 50%,#1a469840,transparent 76%),linear-gradient(180deg,#061328,#0b254f 50%,#061328);
    background-size:100% 1100px;
    background-repeat:repeat-y;
  }

  /* 总览外壳原有的实色会盖住连续环境底，阅读模式下透出外层；保留场景内已有的设备、装饰及受光。 */
  html[data-theme="navy"] #site-viewport #page-content > #composition-story[data-flow-mode="reading"] .ets-flow-track {
    background:transparent;
  }
  html[data-theme="navy"] #site-viewport #page-content > #composition-story[data-flow-mode="reading"] .ets-flow-screen {
    background:radial-gradient(ellipse at 72% 38%,#1a469833,transparent 70%);
  }
  html[data-theme="navy"] #site-viewport #page-content > #composition-story[data-flow-mode="reading"] .ets-flow-screen::after {
    background:linear-gradient(transparent,#061328);
  }
}