/* ==========================================================
   材料体系页
   层次：材料库（按类别分组）→ 选材参考（性能矩阵 + 需求定位）→ 材料服务
   颜色全部取自 theme.css 的变量
   ========================================================== */

.visually-hidden {
  position: absolute !important; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap;
}

/* ---------- 01 材料库：类别分组 ---------- */
.mat-groups { border-bottom: 1px solid var(--line); }
.mat-group {
  display: grid;
  grid-template-columns: minmax(0, 16rem) minmax(0, 1fr);
  gap: 2rem 4rem;
  padding: 2.75rem 0;
  border-top: 1px solid var(--line);
}
.mat-group__head { align-self: start; position: sticky; top: calc(var(--nav-h) + 1.5rem); }
.mat-group__no {
  display: inline-grid; place-items: center;
  width: 2rem; height: 2rem; margin-bottom: 1rem;
  font-size: .875rem; color: #fff; background: var(--brand-red); border-radius: 2px;
}
.mat-group__head h3 { font-size: 1.75rem; line-height: 1.3; }
.mat-group__en { margin-top: .4rem; font-size: .8125rem; letter-spacing: .16em; color: var(--metal); }
.mat-group__desc { margin-top: .9rem; font-size: 1rem; line-height: 1.8; color: var(--muted); }

.mat-group__cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(20rem, 1fr));
  gap: 1.25rem;
}

/* 材料卡片：元素周期表式的符号方块 */
.mat {
  display: flex; flex-direction: column;
  padding: 1.75rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  scroll-margin-top: calc(var(--nav-h) + 1.5rem);
  transition: border-color .2s, box-shadow .2s, background-color .2s;
}
.mat:hover { background: var(--white); border-color: var(--line-strong); box-shadow: 0 14px 36px rgba(15, 17, 21, .06); }
.mat:target { border-color: var(--brand-red); box-shadow: 0 0 0 3px rgba(200, 16, 46, .12); }
.mat__head { display: flex; gap: 1.25rem; align-items: flex-start; }
.mat__sym {
  position: relative; flex: none;
  display: grid; place-items: center;
  width: 4.5rem; height: 4.5rem;
  font-size: 1.875rem; font-weight: 500; letter-spacing: 0;
  color: var(--text-on-dark); background: var(--graphite);
  border-radius: 4px;
}
.mat__sym::after {                     /* 右上角红色标记 */
  content: ""; position: absolute; top: .5rem; right: .5rem;
  width: .375rem; height: .375rem; border-radius: 50%; background: var(--laser-soft);
}
.mat__head h4 { margin: .15rem 0 .6rem; font-size: 1.5rem; line-height: 1.3; }
.mat__grades { display: flex; flex-wrap: wrap; gap: .4rem; }
.mat__grades li {
  padding: .15rem .55rem;
  font-size: .8125rem; color: var(--text);
  background: var(--white); border: 1px solid var(--line-strong); border-radius: 2px;
}
.mat__info {
  display: grid; grid-template-columns: repeat(2, minmax(0, 20rem)); gap: 1rem 1.5rem;
  margin: 1.5rem 0 0; padding-top: 1.25rem; border-top: 1px solid var(--line);
}
.mat__info dt { font-size: .8125rem; font-weight: 600; letter-spacing: .12em; color: var(--metal); }
.mat__info dd { margin: .35rem 0 0; font-size: 1rem; line-height: 1.75; color: var(--text); }

/* ---------- 02 选材参考：性能矩阵 + 需求定位 ---------- */
.select { display: grid; grid-template-columns: minmax(0, 2.1fr) minmax(0, 1fr); gap: 1.5rem; align-items: start; }
.matrix {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 1.25rem 1.75rem 1.5rem;
  overflow-x: auto;
}
.matrix table { width: 100%; border-collapse: collapse; min-width: 34rem; }
.matrix thead th {
  padding: .75rem .5rem 1rem;
  font-size: .875rem; font-weight: 600; letter-spacing: .06em; text-align: left; color: var(--metal);
  border-bottom: 1px solid var(--line-strong);
}
.matrix tbody th {
  padding: .95rem .5rem .95rem 0;
  font-size: 1.0625rem; font-weight: 600; text-align: left; white-space: nowrap; color: var(--text);
}
.matrix tbody th small { display: block; margin: .1rem 0 0 2.6rem; font-size: .75rem; font-weight: 400; color: var(--metal); }
.matrix__sym {
  display: inline-grid; place-items: center; vertical-align: middle;
  width: 1.9rem; height: 1.9rem; margin-right: .7rem;
  font-size: .8125rem; font-weight: 500; color: var(--text-on-dark); background: var(--graphite); border-radius: 3px;
}
.matrix td { padding: .95rem .5rem; }
.matrix tbody tr + tr th, .matrix tbody tr + tr td { border-top: 1px solid var(--line); }
.matrix tbody tr:hover { background: var(--paper); }

.bar { display: inline-flex; gap: 3px; vertical-align: middle; }
.bar i { width: 1.1rem; height: .5rem; border-radius: 1px; background: var(--paper-2); }
.bar i.on { background: var(--text); }
.bar.is-top i.on { background: var(--brand-red); }
.matrix__note {
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: .5rem 1.5rem;
  margin-top: 1.25rem; padding-top: 1rem; border-top: 1px solid var(--line);
  font-size: .875rem; line-height: 1.7; color: var(--muted);
}
.matrix__note span { display: inline-flex; align-items: center; gap: .5rem; white-space: nowrap; }
.bar-key { display: inline-block; width: 1.1rem; height: .5rem; border-radius: 1px; background: var(--brand-red); }

.guide {
  padding: 1.75rem;
  background: var(--graphite); color: var(--text-on-dark);
  border-radius: 10px;
}
.guide h3 { font-size: 1.375rem; margin-bottom: 1rem; }
.guide li {
  display: flex; flex-direction: column; gap: .6rem;
  padding: 1rem 0; border-top: 1px solid var(--line-dark);
}
.guide__need { font-size: .9375rem; color: var(--muted-on-dark); }
.guide__pick { display: flex; flex-wrap: wrap; gap: .5rem; }
.guide__pick a {
  display: inline-flex; align-items: center; gap: .5rem;
  padding: .3rem .75rem .3rem .35rem;
  font-size: .9375rem; color: var(--text-on-dark);
  border: 1px solid rgba(255, 255, 255, .18); border-radius: 3px;
  transition: border-color .2s, background-color .2s;
}
.guide__pick a:hover { border-color: var(--laser-soft); background: rgba(255, 255, 255, .05); }
.guide__pick i {
  font-style: normal; font-size: .75rem;
  display: inline-grid; place-items: center; width: 1.6rem; height: 1.6rem;
  background: rgba(255, 255, 255, .08); border-radius: 2px;
}

/* ---------- 03 材料服务 ---------- */
.mat-service__cards { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1.25rem; }
.mat-service__cards article {
  padding: 2rem;
  background: var(--graphite-2);
  border: 1px solid var(--line-dark);
  border-radius: 8px;
}
.mat-service__cards svg {
  width: 2.75rem; height: 2.75rem;
  fill: none; stroke: var(--metal-light); stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round;
}
.mat-service__cards svg .hl { stroke: var(--laser-soft); stroke-width: 2.2; }
.mat-service__cards h3 { margin: 1.4rem 0 .6rem; font-size: 1.375rem; color: var(--text-on-dark); }
.mat-service__cards p { font-size: 1rem; line-height: 1.85; color: var(--muted-on-dark); }

.powder-flow { margin-top: 3.5rem; }
.powder-flow__title { font-size: .8125rem; letter-spacing: .16em; color: var(--muted-on-dark); margin-bottom: 1.5rem; }
.powder-flow ol {
  position: relative;
  display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 0 1.25rem;
}
.powder-flow ol::before {
  content: ""; position: absolute; left: 0; right: 0; top: .4375rem; height: 1px; background: rgba(255, 255, 255, .18);
}
.powder-flow li { position: relative; display: flex; flex-direction: column; gap: .3rem; padding-top: 2rem; }
.powder-flow li::before {
  content: ""; position: absolute; top: 0; left: 0;
  width: .875rem; height: .875rem; border-radius: 50%;
  background: var(--graphite); border: 2px solid var(--metal-light);
}
.powder-flow li:first-child::before { background: var(--laser-soft); border-color: var(--laser-soft); }
.powder-flow li span { font-size: 1.0625rem; font-weight: 600; color: var(--laser-soft); }
.powder-flow li b { font-size: 1.125rem; color: var(--text-on-dark); }
.powder-flow li small { font-size: .9375rem; line-height: 1.7; color: var(--muted-on-dark); }

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .mat-group { grid-template-columns: minmax(0, 12rem) minmax(0, 1fr); gap: 1.5rem 2.5rem; }
  .select { grid-template-columns: 1fr; }
  .guide ul { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 1.5rem; }
}
@media (max-width: 880px) {
  .matrix table { min-width: 30rem; }
  .bar i { width: .75rem; }
  .matrix tbody th small { display: none; }
  .mat-group { grid-template-columns: 1fr; padding: 2rem 0; }
  .mat-group__head { position: static; display: flex; flex-wrap: wrap; align-items: center; gap: .25rem 1rem; }
  .mat-group__no { margin-bottom: 0; }
  .mat-group__en { margin-top: 0; }
  .mat-group__desc { flex-basis: 100%; margin-top: .25rem; }
  .mat-service__cards { grid-template-columns: 1fr; }
  .powder-flow ol { grid-template-columns: 1fr; gap: 0; }
  .powder-flow ol::before { left: .4375rem; right: auto; top: .5rem; bottom: .5rem; width: 1px; height: auto; }
  .powder-flow li { padding: 0 0 1.5rem 2rem; }
}
@media (max-width: 640px) {
  .matrix::before {
    content: "← 左右滑动查看全部性能 →"; display: block; margin-bottom: .5rem;
    font-size: .8125rem; color: var(--metal); text-align: center;
  }
  .mat-group__cards { grid-template-columns: 1fr; }
  .mat { padding: 1.4rem; }
  .mat__sym { width: 3.75rem; height: 3.75rem; font-size: 1.5rem; }
  .mat__info { grid-template-columns: 1fr; }
  .matrix { padding: 1rem 1rem 1.25rem; }
  .guide ul { grid-template-columns: 1fr; }
}