/* ═══════════════════════════════════════════════════════════════
   AIPEAC Timeline Styles
   ───────────────────────────────────────────────────────────────
   Language colors are sourced from GitHub Linguist:
   https://github.com/github/linguist
   (vendored under .vendor/github-linguist/ as a git submodule)
   ═══════════════════════════════════════════════════════════════ */

:root {
  /* ── Base UI colors (kept) ── */
  --bg:       #0d1117;
  --surface:  #161b22;
  --border:   #30363d;
  --text:     #e6edf3;
  --muted:    #8b949e;
  --accent:   #58a6ff;

  /* ── Special colors ── */
  --docs:     #8b949e;
  --security:   #129ed5;

  /* ── Language colors from GitHub Linguist ── */
  --python:   #167dd8;
  --dart:     #00B4AB;

  --prolog:   #f10745;

  --javascript: #f1e05a;
  --typescript: #3178c6;
  --html:     #e34c26;
  --css:      #663399;
  --java:     #d49a12;

  --cpp:      #f34b7d;
  --bash:     #89e051;
  --powershell: #0265c2;
  --sql:      #ff9d00;
  --tsql:     #ff9d00;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  min-height: 100vh;
  padding: 0 20px 100px;
}

/* ── Header ── */
.page-header {
  text-align: center;
  padding: 60px 0 70px;
}
.page-header h1 {
  font-size: 2rem;
  color: var(--accent);
  letter-spacing: -0.02em;
}
.page-header p {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.9rem;
}

/* ── Filter bar ── */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-top: 28px;
}
.filter-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 7px 22px;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s, box-shadow 0.2s;
  letter-spacing: 0.03em;
  min-width: 72px;
  text-align: center;
}
.filter-btn:hover {
  border-color: var(--accent);
  color: var(--text);
  box-shadow: 0 0 0 1px var(--accent)22;
}
.filter-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--bg);
  box-shadow: 0 0 12px var(--accent)44;
}

/* ── Timeline wrapper ── */
.timeline {
  position: relative;
  max-width: 860px;
  margin: 0 auto;

  /* The vertical spine */
  --spine-left: 50%;
}

/* Spine line */
.timeline::before {
  content: "";
  position: absolute;
  top: 0; bottom: 0;
  left: var(--spine-left);
  width: 2px;
  background: var(--border);
  transform: translateX(-50%);
}

/* ↑ Arrow at the very top */
.timeline-arrow {
  position: absolute;
  top: -22px;
  left: var(--spine-left);
  transform: translateX(-50%);
  width: 0; height: 0;
  border-left:  7px solid transparent;
  border-right: 7px solid transparent;
  border-bottom: 18px solid var(--accent);
}

/* ── Individual items ── */
/*
  HOW TO ADD A NEW ITEM
  ─────────────────────
  Copy one of the blocks below and paste it ABOVE the existing ones
  (newest items go at the top).

  Use  class="timeline-item right"  →  content on the RIGHT side
  Use  class="timeline-item left"   →  content on the LEFT side

  Change the dot colour with  style="--dot: #yourcolor"
  Pick a tag class: .tag-current  .tag-ai  .tag-web
                    .tag-security .tag-mobile .tag-systems .tag-docs
*/
.timeline-item {
  position: relative;
  display: flex;
  align-items: flex-start;
  margin-bottom: 12px;
  /* Entrance animation (JS adds .visible) */
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.45s ease, transform 0.45s ease;
}
.timeline-item.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Dot on the spine */
.timeline-dot {
  --dot: var(--accent);
  position: absolute;
  left: var(--spine-left);
  top: 18px;
  width: 14px; height: 14px;
  border-radius: 50%;
  background: var(--dot);
  border: 2px solid var(--bg);
  transform: translateX(-50%);
  z-index: 1;
  transition: transform 0.2s;
}
.timeline-item:hover .timeline-dot { transform: translateX(-50%) scale(1.35); }

/* Content card */
.timeline-content {
  width: calc(50% - 42px);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 20px;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.timeline-content:hover {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent)22;
}

/* RIGHT side: card sits to the right of the spine */
.timeline-item.right .timeline-content { margin-left: calc(50% + 30px); }

/* LEFT side: card sits to the left of the spine */
.timeline-item.left  .timeline-content { margin-right: calc(50% + 30px); }

/* Connector line (card → dot) */
.timeline-content::before {
  content: "";
  position: absolute;
  top: 25px;
  height: 2px;
  width: 30px;
  background: var(--border);
}
.timeline-item.right .timeline-content::before { left: calc(50% - 30px); }
.timeline-item.left  .timeline-content::before { right: calc(50% - 30px); }

/* ── Tags ── */
.tag {
  display: inline-block;
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  padding: 2px 9px;
  border-radius: 20px;
  margin-bottom: 9px;
}
.tag-current  { background: rgba(53,114,165,.18);  color: var(--python);  }
.tag-ai       { background: rgba(44, 113, 171, 0.397); color: var(--python); }
.tag-web      { background: rgba(241,224,90,.18); color: var(--javascript); }
.tag-mobile   { background: rgba(0,180,171,.15);  color: var(--dart);   }
.tag-systems  { background: rgba(176,114,25,.15); color: var(--java); }
.tag-symolicai{ background: rgba(85, 40, 40, 0.956);  color: var(--prolog); }
.tag-scripts   { background: rgba(137,224,81,.15);  color: var(--bash);   }
/* special tags */
.tag-docs     { background: rgba(139,148,158,.15);color: var(--docs);  }
.tag-security { background: rgba(14, 102, 209, 0.171); color: var(--security); }

.timeline-content h3 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 6px;
}
.timeline-content p {
  font-size: 0.84rem;
  color: var(--muted);
  line-height: 1.55;
}
.timeline-content a {
  color: var(--accent);
  text-decoration: none;
}
.timeline-content a:hover { text-decoration: underline; }

.timeline-date {
  margin-top: 10px;
  font-size: 0.74rem;
  color: var(--muted);
  opacity: 0.6;
}

/* ── Language/framework tags (card footer) ── */
.lang-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-top: 8px;
}
.timeline-item.left  .lang-tags { justify-content: flex-start; }
.lang-tag {
  font-size: 0.62rem;
  font-weight: 600;
  padding: 1px 8px;
  border-radius: 12px;
  border: 1px solid var(--border);
  color: var(--muted);
  letter-spacing: 0.04em;
}

/* ── Month separator (within a year) ── */
.timeline-month {
  position: relative;
  margin: 36px 0 12px;
  text-align: center;
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.35s ease 0.05s, transform 0.35s ease 0.05s;
}
.timeline-month.visible { opacity: 1; transform: translateY(0); }
.timeline-month-label {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  background: var(--bg);
  padding: 0 14px;
  position: relative;
  z-index: 2;
  opacity: 0.55;
}


/* ── Misc / collapsible cards ── */
.timeline-content.folded .fold-body { display: none; }
.fold-footer { margin-top: 6px; }
.timeline-item.right .fold-footer { text-align: left; }
.timeline-item.left  .fold-footer { text-align: right; }
.fold-toggle {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.9rem;
  padding: 0;
  line-height: 1;
  opacity: 0.5;
  transition: opacity 0.2s;
}
.fold-toggle:hover { opacity: 1; }

/* ── Year separator ── */
.timeline-year {
  position: relative;
  margin: 68px 0 48px;
  text-align: center;
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.45s ease 0.1s, transform 0.45s ease 0.1s;
}
.timeline-year.visible {
  opacity: 1;
  transform: translateY(0);
}

.timeline-year-label {
  display: inline-block;
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--bg);
  padding: 0 18px;
  position: relative;
  z-index: 2;
  letter-spacing: -0.01em;
}

.timeline-year::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 0; right: 0;
  height: 1px;
  background: var(--border);
  z-index: 1;
}

/* ── End label ── */
.timeline-end {
  text-align: center;
  margin-top: 10px;
  color: var(--muted);
  font-size: 0.8rem;
  padding-top: 10px;
}

/* ── Scroll-to-top button ── */
#back-to-top {
  position: fixed;
  bottom: 28px; right: 28px;
  width: 42px; height: 42px;
  border-radius: 50%;
  background: var(--accent);
  color: #000;
  font-size: 1.1rem;
  border: none;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s, transform 0.2s;
  z-index: 999;
}
#back-to-top.show { opacity: 1; pointer-events: auto; }
#back-to-top:hover { transform: scale(1.1); }

/* ── Mobile: single column ── */
@media (max-width: 580px) {
  .timeline { --spine-left: 22px; }
  .timeline-item.right .timeline-content,
  .timeline-item.left  .timeline-content {
    margin-left: 50px;
    margin-right: 0;
    width: calc(100% - 50px);
    text-align: left;
  }
  .timeline-item.right .timeline-content::before,
  .timeline-item.left  .timeline-content::before {
    left: -30px; right: auto;
  }
}