:root {
  --bg:        #0d0d12;
  --bg-soft:   #111118;
  --panel:     #16161e;
  --panel-alt: #1a1a24;
  --border:    #2a2a3e;
  --border-lt: #383850;
  --amber:     #e8a838;
  --amber-dim: rgba(232, 168, 56, 0.12);
  --green:     #3ddc84;
  --green-dim: rgba(61, 220, 132, 0.12);
  --red:       #ff4757;
  --red-dim:   rgba(255, 71, 87, 0.12);
  --cyan:      #57c7e3;
  --text:      #e8e8f0;
  --text-dim:  #8888a0;
  --text-faint:#505068;
  --radius:    8px;
  --font:      'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
}

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

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.5;
}

::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg-soft); }
::-webkit-scrollbar-thumb { background: var(--border-lt); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-faint); }

a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ═══════ LAYOUT ═══════ */
.studio {
  display: grid;
  grid-template-columns: 220px 1fr;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "leds leds"
    "side main"
    "side bottom";
  min-height: 100vh;
}

/* LED strip */
.rack-leds {
  grid-area: leds;
  display: flex;
  gap: 12px;
  align-items: center;
  padding: 6px 16px;
  background: var(--bg-soft);
  border-bottom: 1px solid var(--border);
}

.led {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--text-faint);
}
.led--power { background: var(--green); box-shadow: 0 0 6px var(--green); }
.led--sync  { background: var(--cyan); box-shadow: 0 0 6px var(--cyan); }
.led--signal { background: var(--amber); box-shadow: 0 0 6px var(--amber); animation: pulse 2s ease-in-out infinite; }
.led--clip { background: var(--text-faint); }
.led-label {
  font-size: 9px;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-left: -6px;
}

@keyframes pulse {
  0%,100% { box-shadow: 0 0 0 transparent; }
  50% { box-shadow: 0 0 6px currentColor; }
}

/* Sidebar */
.rack-sidebar {
  grid-area: side;
  background: var(--panel);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.sidebar__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 20px 16px 16px;
  border-bottom: 1px solid var(--border);
}

.sidebar__logo {
  font-size: 28px;
  color: var(--amber);
}

.sidebar__title {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.sidebar__user {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.sidebar__username {
  font-weight: 600;
  font-size: 14px;
}

.sidebar__role {
  font-size: 11px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 1.5px;
}

.sidebar__nav {
  list-style: none;
  padding: 8px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav-section {
  font-size: 10px;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 2px;
  padding: 16px 12px 6px;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 6px;
  color: var(--text-dim);
  font-size: 13px;
  font-weight: 500;
  transition: background .15s, color .15s;
  text-decoration: none;
}

.nav-link:hover {
  background: var(--panel-alt);
  color: var(--text);
  text-decoration: none;
}

.nav-link--active {
  background: var(--amber-dim);
  color: var(--amber);
}

.nav-link--logout {
  margin-top: auto;
  color: var(--text-faint);
  font-size: 12px;
}

.nav-link--logout:hover {
  color: var(--red);
  background: var(--red-dim);
}

/* Bottom nav (mobile) */
.rack-bottom-nav {
  display: none;
  grid-area: bottom;
  background: var(--panel);
  border-top: 1px solid var(--border);
  padding: 4px 0;
  justify-content: space-around;
}

.bottom-nav-link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 12px 16px;
  color: var(--text-faint);
  font-size: 22px;
  line-height: 1;
  text-decoration: none;
  transition: color .15s;
}

.bottom-nav-link:hover,
.bottom-nav-link--active {
  color: var(--amber);
  text-decoration: none;
}

/* Main content */
.rack-main {
  grid-area: main;
  padding: 20px 24px;
  overflow-y: auto;
}

/* ═══════ FLASH MESSAGES ═══════ */
.flash-messages {
  margin-bottom: 16px;
}

.flash {
  padding: 12px 16px;
  border-radius: var(--radius);
  font-size: 13px;
  margin-bottom: 8px;
  transition: opacity .3s;
}

.flash--error {
  background: var(--red-dim);
  color: var(--red);
  border: 1px solid var(--red);
}

.flash--info {
  background: var(--cyan-dim);
  color: var(--cyan);
  border: 1px solid var(--cyan);
}

.flash--success {
  background: var(--green-dim);
  color: var(--green);
  border: 1px solid var(--green);
}

/* ═══════ CARDS ═══════ */
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
}

.card__title {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-dim);
  margin-bottom: 12px;
  font-weight: 600;
}

.card--accent {
  border-color: var(--amber);
  box-shadow: 0 0 0 1px var(--amber-dim);
}

/* ═══════ FORM ELEMENTS ═══════ */
.form-group {
  margin-bottom: 16px;
}

.form-label {
  display: block;
  font-size: 12px;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 6px;
}

.form-input {
  width: 100%;
  padding: 10px 12px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  transition: border-color .15s;
}

.form-input:focus {
  outline: none;
  border-color: var(--amber);
  box-shadow: 0 0 0 3px var(--amber-dim);
}

.form-input::placeholder {
  color: var(--text-faint);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-family: var(--font);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, border-color .15s, color .15s;
  background: var(--panel);
  color: var(--text);
  text-decoration: none;
}

.btn:hover {
  background: var(--panel-alt);
  border-color: var(--border-lt);
  text-decoration: none;
}

.btn--primary {
  background: var(--amber);
  color: #000;
  border-color: var(--amber);
}

.btn--primary:hover {
  background: #d49530;
  border-color: #d49530;
}

.btn--danger {
  background: var(--red-dim);
  color: var(--red);
  border-color: var(--red);
}

.btn--danger:hover {
  background: var(--red);
  color: #fff;
}

.btn--ghost {
  background: transparent;
  border-color: transparent;
  color: var(--text-dim);
}

.btn--ghost:hover {
  color: var(--text);
  background: var(--panel);
}

.btn--sm {
  padding: 6px 12px;
  font-size: 12px;
}

/* ═══════ GRID ═══════ */
.grid {
  display: grid;
  gap: 16px;
}

.grid--2 { grid-template-columns: 1fr 1fr; }
.grid--3 { grid-template-columns: 1fr 1fr 1fr; }
.grid--4 { grid-template-columns: repeat(4, 1fr); }

/* ═══════ TABLE ═══════ */
.table-wrap { overflow-x: auto; }

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
}

thead th {
  text-align: left;
  color: var(--text-dim);
  font-weight: 600;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
}

tbody td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
}

tbody tr:last-child td { border-bottom: none; }
tbody tr:hover td { background: var(--panel-alt); }

td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }

/* ═══════ BADGES ═══════ */
.badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.5px;
}

.badge--student { background: var(--cyan-dim); color: var(--cyan); }
.badge--teacher { background: var(--amber-dim); color: var(--amber); }
.badge--admin   { background: var(--red-dim);   color: var(--red); }
.badge--pending { background: var(--border);    color: var(--text-dim); }
.badge--sent    { background: var(--cyan-dim);  color: var(--cyan); }
.badge--completed { background: var(--green-dim); color: var(--green); }

/* ═══════ LOGIN PAGE ═══════ */
.login-page {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: var(--bg);
}

.login-card {
  width: 380px;
  max-width: 90vw;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 40px 32px;
}

.login-card__logo {
  text-align: center;
  font-size: 48px;
  margin-bottom: 8px;
}

.login-card__title {
  text-align: center;
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 4px;
}

.login-card__subtitle {
  text-align: center;
  font-size: 13px;
  color: var(--text-dim);
  margin-bottom: 28px;
}

.login-card .form-input {
  background: var(--bg);
}

/* ═══════ RESPONSIVE ═══════ */
/* ═══════ IFRAME FULLSCREEN ═══════ */
.iframe-card-container:-webkit-full-screen { width:100vw; height:100vh; background:#000; }
.iframe-card-container:-moz-full-screen { width:100vw; height:100vh; background:#000; }
.iframe-card-container:fullscreen { width:100vw; height:100vh; background:#000; }
.iframe-card-container:-webkit-full-screen iframe { height:100vh; }
.iframe-card-container:-moz-full-screen iframe { height:100vh; }
.iframe-card-container:fullscreen iframe { height:100vh; }

@media (max-width: 768px) {
  .studio {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr auto;
    grid-template-areas:
      "leds"
      "main"
      "bottom";
  }
  .rack-sidebar { display: none; }
  .rack-bottom-nav { display: flex; }
  .rack-main { padding: 16px; }
  .grid--2, .grid--3, .grid--4 { grid-template-columns: 1fr; }
}