@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@300;400;500;600;700;800&family=Space+Mono:wght@400;700&display=swap');

  :root {
    --bg: #0a0e1a;
    --bg3: #1a2235;
    --accent: #00e5ff;
    --accent2: #ff6b6b;
    --accent3: #ffd93d;
    --accent4: #a78bfa;
    --text: #e8eaf6;
    --text-dim: #7986a8;
    --border: #1e3050;
    --card: #131d30;
    --glow: 0 0 20px rgba(0,229,255,0.15);
    --pad: clamp(16px, 4vw, 40px);
  }

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

  html, body {
    height: 100%;
    overflow-x: hidden;
  }

  body {
    background: var(--bg);
    color: var(--text);
    font-family: 'Be Vietnam Pro', sans-serif;
    background-image:
      radial-gradient(ellipse at 20% 20%, rgba(0,229,255,0.04) 0%, transparent 50%),
      radial-gradient(ellipse at 80% 80%, rgba(255,107,107,0.04) 0%, transparent 50%);
    display: flex;
    flex-direction: column;
    min-height: 100dvh;
  }

  /* ── HEADER ── */
  header {
    padding: 20px var(--pad) 16px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 14px;
    flex-shrink: 0;
  }

  .logo-icon {
    width: 40px; height: 40px;
    background: linear-gradient(135deg, var(--accent), #0066ff);
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    box-shadow: var(--glow);
    flex-shrink: 0;
  }

  .logo-icon svg { width: 20px; height: 20px; }

  h1 {
    font-size: clamp(16px, 3vw, 22px);
    font-weight: 800;
    letter-spacing: -0.5px;
    background: linear-gradient(90deg, var(--accent), #7aa6ff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
  }

  .subtitle {
    font-size: 11px;
    color: var(--text-dim);
    font-family: 'Space Mono', monospace;
    margin-top: 2px;
  }

  /* ── TABS ── */
  .tabs {
    display: flex;
    gap: 6px;
    padding: 16px var(--pad) 0;
    flex-shrink: 0;
  }

  .tab {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 9px 18px;
    border: 1px solid var(--border);
    border-radius: 8px 8px 0 0;
    cursor: pointer;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-dim);
    background: var(--bg);
    transition: all 0.2s;
    letter-spacing: 0.3px;
    white-space: nowrap;
    user-select: none;
  }

  .tab svg { width: 15px; height: 15px; opacity: 0.6; flex-shrink: 0; }

  .tab.active {
    background: var(--card);
    color: var(--accent);
    border-bottom-color: var(--card);
  }

  .tab.active svg { opacity: 1; stroke: var(--accent); }

  /* ── PANELS ── */
  .panel {
    display: none;
    padding: 24px var(--pad);
    flex: 1;
    min-height: 0;
  }

  .panel.active {
    display: flex;
    flex-direction: column;
    gap: 20px;
  }

  /* ── CONTROLS ── */
  .controls {
    display: flex;
    gap: 14px;
    align-items: flex-end;
    flex-wrap: wrap;
    flex-shrink: 0;
  }

  .control-group { display: flex; flex-direction: column; gap: 6px; }

  label {
    font-size: 11px;
    color: var(--text-dim);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    font-family: 'Space Mono', monospace;
  }

  select, input[type=text] {
    background: var(--card);
    border: 1px solid var(--border);
    color: var(--text);
    border-radius: 8px;
    padding: 9px 14px;
    font-size: 14px;
    font-family: 'Be Vietnam Pro', sans-serif;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
    width: 100%;
  }

  select:focus, input[type=text]:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(0,229,255,0.08);
  }

  select { min-width: min(260px, 100%); cursor: pointer; }

  /* ── STATS ── */
  .stats-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    flex-shrink: 0;
  }

  @media (max-width: 640px) {
    .stats-row { grid-template-columns: repeat(2, 1fr); }
  }

  .stat-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 14px 16px;
    position: relative;
    overflow: hidden;
  }

  .stat-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 2px;
  }

  .stat-card:nth-child(1)::before { background: var(--accent); }
  .stat-card:nth-child(2)::before { background: var(--accent2); }
  .stat-card:nth-child(3)::before { background: var(--accent3); }
  .stat-card:nth-child(4)::before { background: var(--accent4); }

  .stat-label {
    font-size: 10px;
    font-family: 'Space Mono', monospace;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-bottom: 6px;
  }

  .stat-value {
    font-size: clamp(20px, 4vw, 28px);
    font-weight: 800;
    font-family: 'Space Mono', monospace;
    letter-spacing: -1px;
    line-height: 1;
  }

  .stat-card:nth-child(1) .stat-value { color: var(--accent); }
  .stat-card:nth-child(2) .stat-value { color: var(--accent2); }
  .stat-card:nth-child(3) .stat-value { color: var(--accent3); }
  .stat-card:nth-child(4) .stat-value { color: var(--accent4); }

  .stat-sub { font-size: 10px; color: var(--text-dim); margin-top: 4px; }

  /* ── CHART ── */
  .chart-container {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 20px;
    flex: 1;
    min-height: 0;
    display: flex;
    flex-direction: column;
  }

  .chart-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
    flex-shrink: 0;
  }

  .chart-title {
    font-size: 11px;
    font-weight: 600;
    color: var(--text-dim);
    font-family: 'Space Mono', monospace;
    text-transform: uppercase;
    letter-spacing: 1px;
  }

  .chart-legend {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
  }

  .legend-item {
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 10px;
    color: var(--text-dim);
    font-family: 'Space Mono', monospace;
  }

  .legend-dot {
    width: 8px; height: 8px;
    border-radius: 2px;
    flex-shrink: 0;
  }

  .chart-wrap {
    flex: 1;
    min-height: 0;
    position: relative;
  }

  .chart-wrap canvas {
    position: absolute;
    top: 0; left: 0;
    width: 100% !important;
    height: 100% !important;
  }

  /* ── SEARCH ── */
  .search-box {
    position: relative;
    max-width: 440px;
    flex-shrink: 0;
  }

  .search-box input {
    padding: 11px 14px 11px 42px;
    font-size: 15px;
  }

  .search-icon {
    position: absolute;
    left: 13px;
    top: 50%;
    transform: translateY(-50%);
    width: 16px; height: 16px;
    color: var(--text-dim);
    pointer-events: none;
  }

  .autocomplete-list {
    position: absolute;
    top: calc(100% + 4px);
    left: 0; right: 0;
    background: var(--bg3);
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
    z-index: 100;
    max-height: 220px;
    overflow-y: auto;
    box-shadow: 0 8px 32px rgba(0,0,0,0.4);
  }

  .autocomplete-list:empty { display: none; }

  .autocomplete-item {
    padding: 10px 14px;
    cursor: pointer;
    font-size: 13px;
    transition: background 0.12s;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 8px;
  }

  .autocomplete-item:hover { background: rgba(0,229,255,0.07); }

  .class-tag {
    font-size: 10px;
    background: rgba(0,229,255,0.1);
    color: var(--accent);
    padding: 2px 8px;
    border-radius: 20px;
    font-family: 'Space Mono', monospace;
    white-space: nowrap;
    flex-shrink: 0;
  }

  /* ── STUDENT CARD ── */
  .student-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 24px;
    display: none;
  }

  .student-card.visible { display: block; }

  .student-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 20px;
    padding-bottom: 18px;
    border-bottom: 1px solid var(--border);
  }

  .avatar {
    width: 50px; height: 50px;
    background: linear-gradient(135deg, var(--accent), #0044ff);
    border-radius: 14px;
    display: flex; align-items: center; justify-content: center;
    font-size: 20px;
    font-weight: 800;
    color: #000;
    flex-shrink: 0;
  }

  .student-name { font-size: clamp(15px, 3vw, 19px); font-weight: 800; letter-spacing: -0.3px; }
  .student-meta { font-size: 12px; color: var(--text-dim); margin-top: 3px; font-family: 'Space Mono', monospace; }

  .subjects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 12px;
  }

  .subject-row {
    background: var(--bg3);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 14px 16px;
  }

  .subject-name {
    font-size: 10px;
    color: var(--text-dim);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-bottom: 8px;
    font-family: 'Space Mono', monospace;
  }

  .subject-score-row {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 8px;
  }

  .subject-score {
    font-size: 28px;
    font-weight: 800;
    font-family: 'Space Mono', monospace;
    line-height: 1;
  }

  .rank-badge { text-align: right; }
  .rank-num { font-size: 13px; font-weight: 700; font-family: 'Space Mono', monospace; color: var(--accent3); }
  .rank-total { font-size: 10px; color: var(--text-dim); }

  .rank-bar-bg {
    height: 3px;
    background: var(--border);
    border-radius: 2px;
    margin-top: 10px;
    overflow: hidden;
  }

  .rank-bar-fill {
    height: 100%;
    border-radius: 2px;
    transition: width 0.6s cubic-bezier(.4,0,.2,1);
  }

  /* ── EMPTY / NO RESULT ── */
  .no-result {
    text-align: center;
    padding: 40px;
    color: var(--text-dim);
    font-size: 14px;
    display: none;
  }
  .no-result.visible { display: block; }

  .empty-hint {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-dim);
    font-size: 13px;
    opacity: 0.5;
  }

  /* ── RESPONSIVE ── */
  @media (max-width: 480px) {
    .tab { padding: 8px 12px; font-size: 12px; gap: 6px; }
    .stat-card { padding: 12px 14px; }
    .chart-legend { display: none; }
    .subjects-grid { grid-template-columns: 1fr; }
    .student-card { padding: 16px; }
  }