/* ════════════════════════════════════════════════════
   ALGORITHM OBSERVATORY — DESIGN TOKENS

   Palette:
     paper     #FAFAF7  warm paper background
     ink       #1A1D29  near-black text
     indigo    #2D5BFF  primary accent — comparing / active
     coral     #FF6B4A  swap / conflict
     mint      #1FB070  sorted / found / success
     amber     #F5A623  pivot / special marker
     mist      #E8E6DD  bar fill, borders, quiet surfaces

   Type:
     Space Grotesk  — headings, brand, algorithm names
     IBM Plex Mono  — all numbers, stats, code-like data
     Inter          — body copy, labels, descriptions
════════════════════════════════════════════════════ */
:root{
  --paper:      #FAFAF7;
  --paper-deep: #F2F0E8;
  --ink:        #1A1D29;
  --ink-soft:   #5B5F6F;
  --ink-faint:  #9A9DA8;

  --indigo:     #2D5BFF;
  --indigo-soft:#E8EDFF;
  --coral:      #FF6B4A;
  --coral-soft: #FFE9E2;
  --mint:       #1FB070;
  --mint-soft:  #E2F6ED;
  --amber:      #F5A623;
  --amber-soft: #FDF0DA;

  --mist:       #E8E6DD;
  --mist-deep:  #D8D5C8;
  --line:       #DEDBD0;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  --shadow-sm: 0 1px 2px rgba(26,29,41,0.06);
  --shadow-md: 0 4px 16px rgba(26,29,41,0.08);
  --shadow-lg: 0 12px 32px rgba(26,29,41,0.12);

  --font-display: 'Space Grotesk', sans-serif;
  --font-mono:    'IBM Plex Mono', monospace;
  --font-body:    'Inter', sans-serif;
}

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

html{font-size:16px}

body{
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font-body);
  min-height:100vh;
  display:flex;
  flex-direction:column;
  -webkit-font-smoothing:antialiased;
}

button{font-family:inherit;border:none;background:none;cursor:pointer;color:inherit}
input,textarea{font-family:inherit;color:inherit}
input:focus-visible,textarea:focus-visible,button:focus-visible{
  outline:2px solid var(--indigo);
  outline-offset:2px;
}

/* ════════════════════════════════════════════════════
   TOP BAR
════════════════════════════════════════════════════ */
.topbar{
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 28px;
  background:var(--paper);
  border-bottom:1px solid var(--line);
  position:sticky;top:0;z-index:50;
}

.brand{display:flex;align-items:center;gap:12px}

.brand-mark{
  width:38px;height:38px;border-radius:var(--radius-md);
  background:var(--ink);color:var(--paper);
  display:flex;align-items:center;justify-content:center;
  font-size:16px;
  box-shadow:var(--shadow-sm);
}

.brand-text{display:flex;flex-direction:column;line-height:1.25}
.brand-name{font-family:var(--font-display);font-weight:700;font-size:1.05rem;letter-spacing:-0.01em}
.brand-sub{font-family:var(--font-mono);font-size:0.7rem;color:var(--ink-faint);letter-spacing:0.02em}

.topbar-actions{display:flex;gap:8px}

.icon-btn{
  width:38px;height:38px;border-radius:var(--radius-md);
  display:flex;align-items:center;justify-content:center;
  background:var(--paper-deep);
  border:1px solid var(--line);
  color:var(--ink-soft);
  font-size:0.95rem;
  transition:transform 0.12s ease,background 0.12s ease,color 0.12s ease,border-color 0.12s ease;
}
.icon-btn:hover{background:var(--indigo-soft);color:var(--indigo);border-color:var(--indigo)}
.icon-btn:active{transform:scale(0.92)}

/* ════════════════════════════════════════════════════
   LAYOUT GRID
════════════════════════════════════════════════════ */
.layout{
  flex:1;
  display:grid;
  grid-template-columns:280px 1fr 300px;
  gap:0;
  min-height:0;
}

/* ════════════════════════════════════════════════════
   LEFT RAIL
════════════════════════════════════════════════════ */
.rail{
  border-right:1px solid var(--line);
  padding:20px;
  overflow-y:auto;
  display:flex;flex-direction:column;gap:24px;
  background:var(--paper);
}

.rail-section{display:flex;flex-direction:column;gap:10px}

.rail-title{
  font-family:var(--font-display);
  font-size:0.78rem;
  font-weight:700;
  text-transform:uppercase;
  letter-spacing:0.06em;
  color:var(--ink-soft);
}

.input-label{font-size:0.72rem;color:var(--ink-faint);letter-spacing:0.01em}

.array-input{
  width:100%;
  border:1.5px solid var(--line);
  border-radius:var(--radius-md);
  padding:10px 12px;
  font-family:var(--font-mono);
  font-size:0.85rem;
  background:var(--paper-deep);
  resize:vertical;
  transition:border-color 0.15s ease,box-shadow 0.15s ease;
  line-height:1.5;
}
.array-input:focus{
  border-color:var(--indigo);
  background:#fff;
  box-shadow:0 0 0 3px var(--indigo-soft);
  outline:none;
}

.input-row{display:flex;align-items:center;gap:10px;flex-wrap:wrap}

.input-hint{font-size:0.72rem;color:var(--coral);font-family:var(--font-mono)}

.search-input{
  width:100%;
  border:1.5px solid var(--line);
  border-radius:var(--radius-md);
  padding:10px 12px;
  font-family:var(--font-mono);
  font-size:0.9rem;
  background:var(--paper-deep);
  transition:border-color 0.15s ease,box-shadow 0.15s ease;
}
.search-input:focus{
  border-color:var(--amber);
  background:#fff;
  box-shadow:0 0 0 3px var(--amber-soft);
  outline:none;
}

.rail-note{font-size:0.72rem;color:var(--ink-faint);line-height:1.5}

/* ── Algorithm cards ── */
.algo-list{display:flex;flex-direction:column;gap:6px}

.algo-card{
  display:flex;align-items:center;gap:10px;
  padding:10px 12px;
  border-radius:var(--radius-md);
  border:1.5px solid var(--line);
  background:var(--paper);
  cursor:pointer;
  transition:transform 0.1s ease,border-color 0.12s ease,background 0.12s ease,box-shadow 0.12s ease;
  text-align:left;
  width:100%;
}

.algo-card:hover{
  border-color:var(--indigo);
  background:var(--indigo-soft);
  transform:translateX(2px);
}

.algo-card:active{transform:translateX(2px) scale(0.98)}

.algo-card.active{
  border-color:var(--indigo);
  background:var(--indigo);
  box-shadow:var(--shadow-md);
}

.algo-card.active .algo-card-name,
.algo-card.active .algo-card-big-o{color:#fff}

.algo-card-icon{
  width:28px;height:28px;border-radius:var(--radius-sm);
  background:var(--mist);
  display:flex;align-items:center;justify-content:center;
  font-size:0.75rem;color:var(--ink-soft);
  flex-shrink:0;
  transition:background 0.12s ease,color 0.12s ease;
}
.algo-card.active .algo-card-icon{background:rgba(255,255,255,0.2);color:#fff}

.algo-card-text{display:flex;flex-direction:column;gap:1px;min-width:0}
.algo-card-name{font-family:var(--font-display);font-weight:600;font-size:0.85rem;color:var(--ink)}
.algo-card-big-o{font-family:var(--font-mono);font-size:0.68rem;color:var(--ink-faint)}

/* ════════════════════════════════════════════════════
   BUTTONS — general
════════════════════════════════════════════════════ */
.btn{
  display:inline-flex;align-items:center;gap:7px;
  padding:10px 18px;
  border-radius:var(--radius-md);
  font-family:var(--font-display);
  font-weight:600;
  font-size:0.82rem;
  transition:transform 0.1s ease,background 0.12s ease,box-shadow 0.12s ease,color 0.12s ease;
  white-space:nowrap;
}

.btn-primary{
  background:var(--ink);
  color:var(--paper);
  box-shadow:var(--shadow-sm);
}
.btn-primary:hover{background:var(--indigo);box-shadow:var(--shadow-md);transform:translateY(-1px)}
.btn-primary:active{transform:translateY(0) scale(0.97)}

.btn-ghost{
  background:transparent;
  border:1.5px solid var(--line);
  color:var(--ink-soft);
}
.btn-ghost:hover{border-color:var(--ink-soft);color:var(--ink);background:var(--paper-deep)}
.btn-ghost:active{transform:scale(0.97)}

.btn-sm{padding:7px 14px;font-size:0.74rem}

/* ════════════════════════════════════════════════════
   STAGE (center)
════════════════════════════════════════════════════ */
.stage-wrap{
  display:flex;flex-direction:column;
  padding:20px 28px;
  min-width:0;
  background:
    radial-gradient(circle at 50% 0%, rgba(45,91,255,0.035) 0%, transparent 55%),
    var(--paper);
}

.stage-header{
  display:flex;align-items:center;justify-content:space-between;
  margin-bottom:16px;
  flex-wrap:wrap;gap:10px;
}

.stage-title{display:flex;align-items:baseline;gap:10px;flex-wrap:wrap}
.stage-algo-name{font-family:var(--font-display);font-size:1.3rem;font-weight:700;letter-spacing:-0.01em}
.stage-algo-tag{font-family:var(--font-mono);font-size:0.78rem;color:var(--ink-faint)}

.stage-status{
  font-family:var(--font-mono);
  font-size:0.74rem;
  padding:5px 12px;
  border-radius:999px;
  background:var(--mist);
  color:var(--ink-soft);
  letter-spacing:0.03em;
  transition:background 0.2s ease,color 0.2s ease;
}
.stage-status.status-running{background:var(--indigo-soft);color:var(--indigo)}
.stage-status.status-done{background:var(--mint-soft);color:var(--mint)}
.stage-status.status-paused{background:var(--amber-soft);color:var(--amber)}

.stage{
  flex:1;
  max-height:330px;
  border-radius:var(--radius-lg);
  background:#fff;
  border:1px solid var(--line);
  box-shadow:var(--shadow-sm);
  position:relative;
  display:flex;
  align-items:center;
  justify-content:center;
  padding:24px 20px 36px;
  overflow:hidden;
}

.stage-empty{
  display:flex;flex-direction:column;align-items:center;gap:10px;
  color:var(--ink-faint);
  text-align:center;
  max-width:280px;
}
.stage-empty i{font-size:2rem;color:var(--mist-deep)}
.stage-empty p{font-size:0.86rem;line-height:1.5}

.bars-svg{width:100%;height:100%;display:block}

/* Bar elements (drawn as SVG rects + text via JS, styled here for reference) */
.bar-rect{transition:fill 0.18s ease,x 0.25s cubic-bezier(0.4,0,0.2,1)}
.bar-trace{transition:opacity 0.18s ease}
.bar-label{font-family:var(--font-mono);font-size:11px;fill:var(--ink-soft)}

/* ── Legend ── */
.legend{
  display:flex;gap:18px;flex-wrap:wrap;
  margin-top:14px;
  padding:10px 16px;
  border-radius:var(--radius-md);
  background:var(--paper-deep);
  border:1px solid var(--line);
}
.legend-item{
  display:flex;align-items:center;gap:7px;
  font-size:0.76rem;color:var(--ink-soft);
  font-family:var(--font-mono);
}
.legend-dot{width:11px;height:11px;border-radius:3px;display:inline-block}
.dot-default{background:var(--mist-deep)}
.dot-compare{background:var(--indigo)}
.dot-swap{background:var(--coral)}
.dot-pivot{background:var(--amber)}
.dot-sorted{background:var(--mint)}

/* ════════════════════════════════════════════════════
   TRANSPORT CONTROLS
════════════════════════════════════════════════════ */
.transport{
  display:flex;align-items:center;gap:16px;
  margin-top:16px;
  padding:14px 20px;
  border-radius:var(--radius-lg);
  background:var(--ink);
  box-shadow:var(--shadow-md);
  flex-wrap:wrap;
}

.trans-btn{
  width:38px;height:38px;border-radius:50%;
  display:flex;align-items:center;justify-content:center;
  background:rgba(255,255,255,0.08);
  color:#fff;
  font-size:0.85rem;
  transition:transform 0.12s ease,background 0.12s ease;
  flex-shrink:0;
}
.trans-btn:hover{background:rgba(255,255,255,0.16)}
.trans-btn:active{transform:scale(0.88)}

.trans-btn-main{
  width:46px;height:46px;
  background:var(--indigo);
  font-size:1rem;
}
.trans-btn-main:hover{background:#4a72ff;box-shadow:0 0 0 6px rgba(45,91,255,0.18)}

.transport-progress{
  flex:1;min-width:160px;
  display:flex;flex-direction:column;gap:5px;
}

.transport-progress-label{
  font-family:var(--font-mono);font-size:0.72rem;
  color:rgba(255,255,255,0.55);
  text-align:right;
}

input[type="range"]{
  -webkit-appearance:none;appearance:none;
  width:100%;height:5px;border-radius:4px;
  background:rgba(255,255,255,0.15);
  outline:none;cursor:pointer;
}
input[type="range"]::-webkit-slider-thumb{
  -webkit-appearance:none;
  width:16px;height:16px;border-radius:50%;
  background:var(--indigo);
  border:2.5px solid #fff;
  box-shadow:0 1px 4px rgba(0,0,0,0.3);
  cursor:pointer;
  transition:transform 0.1s ease;
}
input[type="range"]::-webkit-slider-thumb:hover{transform:scale(1.15)}
input[type="range"]::-moz-range-thumb{
  width:16px;height:16px;border-radius:50%;
  background:var(--indigo);border:2.5px solid #fff;cursor:pointer;
}

.speed-control{
  display:flex;align-items:center;gap:8px;
  color:rgba(255,255,255,0.7);font-size:0.85rem;
  min-width:140px;
}
.speed-control input[type="range"]{width:80px}
#speed-label{font-family:var(--font-mono);font-size:0.72rem;min-width:52px;color:rgba(255,255,255,0.8)}

/* ════════════════════════════════════════════════════
   RIGHT INSPECTOR
════════════════════════════════════════════════════ */
.inspector{
  border-left:1px solid var(--line);
  padding:20px;
  overflow-y:auto;
  display:flex;flex-direction:column;gap:22px;
  background:var(--paper-deep);
}

.insp-section{display:flex;flex-direction:column;gap:12px}

.insp-title{
  display:flex;align-items:center;gap:8px;
  font-family:var(--font-display);
  font-size:0.78rem;font-weight:700;
  text-transform:uppercase;letter-spacing:0.05em;
  color:var(--ink-soft);
}
.insp-title i{font-size:0.78rem;color:var(--indigo)}

.insp-sub{font-size:0.74rem;color:var(--ink-faint);line-height:1.5;margin-top:-6px}

/* ── Stats grid ── */
.stat-grid{display:grid;grid-template-columns:1fr 1fr;gap:8px}

.stat-box{
  background:#fff;
  border:1px solid var(--line);
  border-radius:var(--radius-md);
  padding:12px 10px;
  text-align:center;
  transition:border-color 0.2s ease,transform 0.2s ease;
}

.stat-num{
  display:block;
  font-family:var(--font-mono);
  font-size:1.3rem;font-weight:600;
  color:var(--ink);
  line-height:1.2;
}

.stat-label{
  display:block;
  font-size:0.66rem;color:var(--ink-faint);
  margin-top:3px;letter-spacing:0.01em;
}

/* ── Complexity table ── */
.complexity-grid{
  background:#fff;border:1px solid var(--line);border-radius:var(--radius-md);
  overflow:hidden;
}

.cx-row{
  display:flex;justify-content:space-between;align-items:center;
  padding:9px 14px;
  border-bottom:1px solid var(--line);
  font-size:0.8rem;
}
.cx-row:last-child{border-bottom:none}
.cx-label{color:var(--ink-soft)}
.cx-val{font-family:var(--font-mono);font-weight:600;color:var(--ink)}

/* ── Explanation text ── */
.explain-text{
  background:#fff;border:1px solid var(--line);border-radius:var(--radius-md);
  padding:14px;font-size:0.82rem;line-height:1.6;color:var(--ink-soft);
  min-height:70px;
}

/* ── Race results ── */
.race-results{display:flex;flex-direction:column;gap:8px}

.race-empty{font-size:0.78rem;color:var(--ink-faint);font-style:italic}

.race-row{
  display:flex;align-items:center;justify-content:space-between;
  background:#fff;border:1px solid var(--line);border-radius:var(--radius-sm);
  padding:8px 12px;font-size:0.76rem;
}
.race-row-name{font-family:var(--font-display);font-weight:600}
.race-row-steps{font-family:var(--font-mono);color:var(--indigo);font-weight:600}

/* ════════════════════════════════════════════════════
   FOOTER
════════════════════════════════════════════════════ */
.page-footer{
  text-align:center;
  padding:12px;
  font-size:0.72rem;
  color:var(--ink-faint);
  border-top:1px solid var(--line);
  background:var(--paper);
}

/* ════════════════════════════════════════════════════
   RESPONSIVE
════════════════════════════════════════════════════ */
@media(max-width:1100px){
  .layout{grid-template-columns:260px 1fr}
  .inspector{
    grid-column:1 / -1;
    border-left:none;border-top:1px solid var(--line);
    flex-direction:row;flex-wrap:wrap;
  }
  .insp-section{flex:1;min-width:220px}
}

@media(max-width:760px){
  .layout{grid-template-columns:1fr}
  .rail{border-right:none;border-bottom:1px solid var(--line)}
  .stage{min-height:280px}
  .transport{flex-direction:column;align-items:stretch}
  .speed-control{justify-content:space-between}
}

/* Respect reduced motion */
@media(prefers-reduced-motion:reduce){
  *{transition-duration:0.01ms!important;animation-duration:0.01ms!important}
}