/* timeline.css — AI Timeline page */

.tl-wrap { position: relative; max-width: 980px; margin: 0 auto; padding: 0 32px 80px; }

/* floating year indicator */
.tl-year {
  position: fixed; right: 40px; top: 50%; transform: translateY(-50%); z-index: 30;
  font-family: var(--mono); font-weight: 700; font-size: 64px; letter-spacing: -0.05em;
  background: var(--grad); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
  opacity: 0; pointer-events: none;
}
.tl-year .lbl { display: block; font-family: var(--sans); font-size: 11px; font-weight: 650; letter-spacing: .12em;
  text-transform: uppercase; -webkit-text-fill-color: var(--ink-3); text-align: right; margin-bottom: 2px; }

/* spine */
.tl-body { position: relative; }
.tl-spine { position: absolute; left: 50%; top: 0; bottom: 0; width: 2px; transform: translateX(-50%);
  background: var(--line-2); border-radius: 2px; }
.tl-spine-fill { position: absolute; left: 0; top: 0; width: 100%; height: 0%;
  background: linear-gradient(180deg, var(--blue), var(--violet), var(--cyan)); border-radius: 2px; }
.tl-spine-head { position: absolute; left: 50%; transform: translate(-50%, -50%); top: 0;
  width: 14px; height: 14px; border-radius: 50%; background: var(--grad);
  box-shadow: 0 0 0 5px rgba(124,58,237,.15), 0 2px 10px rgba(124,58,237,.4); }

/* era chapter header */
.tl-era { position: relative; text-align: center; padding: 74px 0 40px; }
.tl-era .range { font-family: var(--mono); font-size: 12px; font-weight: 600; letter-spacing: .14em;
  text-transform: uppercase; color: var(--ink-3); background: #fdfdfe; display: block;
  width: fit-content; margin: 0 auto; padding: 0 16px; position: relative; z-index: 2; }
.tl-era h2 { font-size: clamp(26px, 3.6vw, 42px); font-weight: 700; letter-spacing: -0.035em; margin: 10px 0 0;
  background: #fdfdfe; display: inline-block; padding: 0 22px; position: relative; z-index: 2; }
.tl-era .blurb { font-size: 15px; color: var(--ink-2); max-width: 52ch; margin: 12px auto 0; line-height: 1.6;
  background: #fdfdfe; position: relative; z-index: 2; padding: 0 18px; }

/* event rows */
.tl-item { position: relative; display: grid; grid-template-columns: 1fr 76px 1fr; align-items: center; margin-bottom: 26px; }
.tl-dot { grid-column: 2; justify-self: center; width: 13px; height: 13px; border-radius: 50%;
  background: #fff; border: 3px solid var(--dc, var(--blue)); z-index: 2;
  box-shadow: 0 0 0 4px #fdfdfe; }
.tl-item.milestone .tl-dot { width: 17px; height: 17px; border-width: 4px;
  box-shadow: 0 0 0 4px #fdfdfe, 0 0 18px color-mix(in srgb, var(--dc) 50%, transparent); }

.tl-card { background: #fff; border: 1px solid var(--line); border-radius: var(--r-md); padding: 20px 24px;
  box-shadow: var(--shadow-sm); position: relative; }
.tl-card:hover { box-shadow: var(--shadow-md); border-color: var(--line-2); }
.tl-item:nth-child(odd) .tl-card { grid-column: 1; text-align: right; }
.tl-item:nth-child(even) .tl-card { grid-column: 3; grid-row: 1; }
.tl-item:nth-child(odd) .tl-card::after, .tl-item:nth-child(even) .tl-card::before {
  content: ''; position: absolute; top: 50%; width: 26px; height: 1.5px; background: var(--line-2); }
.tl-item:nth-child(odd) .tl-card::after { left: 100%; }
.tl-item:nth-child(even) .tl-card::before { right: 100%; }

.tl-item.milestone .tl-card { border: 1.5px solid transparent; border-radius: var(--r-lg); padding: 26px 28px;
  background: linear-gradient(#fff, #fff) padding-box, var(--grad) border-box;
  box-shadow: 0 6px 28px rgba(99,72,237,.12); }

.tl-meta { display: flex; gap: 10px; align-items: center; font-size: 12px; }
.tl-item:nth-child(odd) .tl-meta { justify-content: flex-end; }
.tl-date { font-family: var(--mono); font-weight: 600; color: var(--ink-3); letter-spacing: .02em; }
.tl-cat { font-size: 10.5px; font-weight: 700; letter-spacing: .07em; text-transform: uppercase;
  padding: 3px 9px; border-radius: 999px; }
.tlc-research { background: rgba(124,58,237,.1); color: var(--violet); }
.tlc-model { background: rgba(37,99,235,.1); color: var(--blue); }
.tlc-product { background: rgba(219,39,119,.1); color: #db2777; }
.tlc-funding { background: rgba(16,185,129,.12); color: #0a8a60; }

.tl-card h3 { font-size: 16.5px; font-weight: 650; letter-spacing: -0.02em; line-height: 1.3; margin: 10px 0 0; }
.tl-item.milestone .tl-card h3 { font-size: 20px; }
.tl-card p { font-size: 13.5px; color: var(--ink-2); line-height: 1.55; margin: 8px 0 0; }

/* end cap */
.tl-end { text-align: center; padding: 50px 0 0; position: relative; z-index: 2; }
.tl-end .pulse { width: 16px; height: 16px; border-radius: 50%; background: var(--grad); margin: 0 auto;
  box-shadow: 0 0 0 6px rgba(124,58,237,.14); }
.tl-end .t { font-family: var(--mono); font-size: 13px; font-weight: 600; color: var(--ink-2); margin-top: 18px; }
.tl-end .s { font-size: 13px; color: var(--ink-3); margin-top: 6px; }

@media (max-width: 860px) {
  .tl-year { display: none; }
  .tl-item { grid-template-columns: 44px 1fr; }
  .tl-spine { left: 22px; transform: none; }
  .tl-dot { grid-column: 1; grid-row: 1; }
  .tl-item:nth-child(odd) .tl-card, .tl-item:nth-child(even) .tl-card { grid-column: 2; grid-row: 1; text-align: left; }
  .tl-item:nth-child(odd) .tl-meta { justify-content: flex-start; }
  .tl-item:nth-child(odd) .tl-card::after { display: none; }
  .tl-item:nth-child(even) .tl-card::before { right: 100%; width: 18px; }
  .tl-era h2, .tl-era .blurb { background: transparent; }
}