/* s4ros.it course hub — 19" rack in a dim lab, not a SaaS landing. */

:root {
  --void: #0c0e11;
  --chassis: #171b20;
  --face: #262c34;
  --face-hi: #2f3640;
  --rail: #c3c9d0;
  --rail-dark: #8e969f;
  --hole: #2a3038;
  --silk: #eef3f7;
  --mute: #8d97a3;
  --line: rgba(238, 243, 247, 0.1);
  --led-netflix: #ff5a4c;
  --led-pliant: #2ad6c0;
  --focus: #e2b03a;
  --display: "Archivo Narrow", "Arial Narrow", sans-serif;
  --sans: "Source Sans 3", "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
}

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

html { color-scheme: dark; }

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(1200px 600px at 50% -10%, rgba(80, 96, 110, 0.18), transparent 60%),
    var(--void);
  color: var(--silk);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.45;
}

a { color: inherit; }

:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
}

.skip {
  position: absolute;
  left: -999px;
  top: 8px;
}
.skip:focus {
  left: 12px;
  z-index: 40;
  background: var(--face);
  color: var(--silk);
  padding: 8px 12px;
}

.lab {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 28px 16px 40px;
}

.rack {
  position: relative;
  width: min(920px, 100%);
  min-height: calc(100vh - 56px);
  display: flex;
  flex-direction: column;
  background:
    linear-gradient(180deg, #1c2128 0%, var(--chassis) 18%, #12151a 100%);
  border-top: 1px solid #3a424c;
  border-bottom: 1px solid #0a0c0f;
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.06) inset,
    0 28px 80px rgba(0, 0, 0, 0.55);
  padding: 18px 56px 22px;
}

.rail {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 40px;
  background:
    radial-gradient(circle at 50% 14px, var(--hole) 3.4px, transparent 3.7px) 0 8px / 100% 28px,
    linear-gradient(90deg, #d5dae0, var(--rail) 40%, var(--rail-dark));
  box-shadow:
    inset 3px 0 6px rgba(255, 255, 255, 0.28),
    inset -2px 0 4px rgba(0, 0, 0, 0.25);
}
.rail--left { left: 0; }
.rail--right {
  right: 0;
  background:
    radial-gradient(circle at 50% 14px, var(--hole) 3.4px, transparent 3.7px) 0 8px / 100% 28px,
    linear-gradient(90deg, var(--rail-dark), var(--rail) 60%, #d5dae0);
}

.pdu {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  padding: 10px 4px 16px;
  border-bottom: 1px solid var(--line);
}

.brand {
  margin: 0;
  font-family: var(--display);
  font-weight: 700;
  font-size: clamp(28px, 4vw, 40px);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  line-height: 1;
}

.tag, .clock, .bay, .stack, .pdu--foot {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--mute);
}

.tag, .clock, .brand, .bay { margin: 0; }

.clock time {
  font-variant-numeric: tabular-nums;
  color: var(--silk);
}

.bay {
  margin: 18px 4px 10px;
}

main {
  display: grid;
  gap: 12px;
}

.blade {
  display: grid;
  grid-template-columns: 18px 1fr auto;
  align-items: center;
  gap: 18px 20px;
  padding: 24px 22px 24px 18px;
  text-decoration: none;
  background:
    linear-gradient(180deg, var(--face-hi), var(--face));
  border: 1px solid #3d4652;
  border-left-width: 3px;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.07),
    0 8px 18px rgba(0, 0, 0, 0.22);
  transition: transform 160ms ease, border-color 160ms ease, box-shadow 160ms ease;
}
.blade--netflix { border-left-color: var(--led-netflix); }
.blade--pliant { border-left-color: var(--led-pliant); }

.blade:hover,
.blade:focus-visible {
  transform: translateY(-2px);
  border-color: #5a6573;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.1),
    0 14px 28px rgba(0, 0, 0, 0.32);
}

.led {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  justify-self: center;
  box-shadow: 0 0 0 2px rgba(0, 0, 0, 0.35) inset;
}

.blade--netflix .led {
  background: var(--led-netflix);
  box-shadow: 0 0 10px var(--led-netflix), 0 0 0 2px rgba(0, 0, 0, 0.35) inset;
}
.blade--pliant .led {
  background: var(--led-pliant);
  box-shadow: 0 0 10px var(--led-pliant), 0 0 0 2px rgba(0, 0, 0, 0.35) inset;
}

.blade__copy { min-width: 0; }

.silk {
  display: block;
  font-family: var(--display);
  font-weight: 700;
  font-size: clamp(28px, 4.2vw, 44px);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  line-height: 0.95;
}

.role {
  display: block;
  margin-top: 6px;
  font-weight: 600;
  font-size: 16px;
}

.stack {
  display: block;
  margin-top: 4px;
  text-transform: none;
  letter-spacing: 0.02em;
  font-size: 13px;
}

.eject {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  padding: 16px 14px;
  border: 1px solid #4a5562;
  background:
    repeating-linear-gradient(
      180deg,
      #3d4650 0 2px,
      #2c333b 2px 5px
    );
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08);
  white-space: nowrap;
}

.blade:hover .eject,
.blade:focus-visible .eject {
  border-color: var(--focus);
  color: var(--focus);
}

.slots {
  margin: 16px 0 8px;
  display: grid;
  gap: 7px;
  flex: 1;
  align-content: stretch;
  grid-auto-rows: 1fr;
}
.slots span {
  display: block;
  min-height: 10px;
  background: repeating-linear-gradient(
    90deg,
    #1a1e24 0 12px,
    #22282f 12px 14px
  );
  border: 1px solid #101318;
  opacity: 0.7;
}

.pdu--foot {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 14px 4px 4px;
  border-top: 1px solid var(--line);
  border-bottom: 0;
  text-transform: none;
  letter-spacing: 0.04em;
}
.pdu--foot p { margin: 0; }
.pdu--foot a { text-decoration: none; border-bottom: 1px solid #4a5562; }
.pdu--foot a:hover { color: var(--silk); border-bottom-color: var(--focus); }

@media (max-width: 720px) {
  .lab { padding: 12px 10px 24px; }
  .rack { padding: 14px 30px 16px; }
  .rail { width: 22px; }
  .blade {
    grid-template-columns: 14px 1fr;
  }
  .eject {
    grid-column: 2;
    justify-self: start;
  }
  .clock { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .blade { transition: none; }
  .blade:hover, .blade:focus-visible { transform: none; }
}