body{ background:#f6f7fb; }
    .content-area{
      background:#fff;
      border:1px solid rgba(0,0,0,.08);
      border-radius:14px;
      padding:18px 18px;
      box-shadow:0 10px 30px rgba(0,0,0,.06);
    }
    .toolbar-wrap{
      display:flex;
      flex-direction:column;
      align-items:center;
      gap:10px;
    }
    .quiz-toolbar{
      display:flex;
      gap:6px;
      flex-wrap:wrap;
      justify-content:center;
    }
    .quiz-toolbar .btn{
      font-size:16px;
      border-radius:12px;
      padding:5px 14px;
    }
    .explain-area{
      background:#fff;
      border:1px solid rgba(0,0,0,.08);
      border-radius:14px;
      padding:18px 18px;
      box-shadow:0 10px 30px rgba(0,0,0,.06);
      top: 90px;
      max-height: calc(100vh - 120px);
      overflow:auto;
    }
    .explain-header{
      border-bottom:1px solid rgba(0,0,0,.07);
      padding-bottom:10px;
      margin-bottom:14px;
    }
    .answer-status{
      display:flex;
      align-items:center;
      gap:10px;
    }
    .badge-dot{
      width:10px; height:10px; border-radius:50%;
      display:inline-block;
    }
    .badge-dot.ok{ background:#16a34a; }
    .badge-dot.bad{ background:#dc2626; }

    .question-card h5{ line-height:1.35; }
    .option-item{
      border:1px solid rgba(0,0,0,.10);
      border-radius:10px;
      padding:12px 12px;
      margin-bottom:10px;
      cursor:pointer;
      transition:.15s ease;
      user-select:none;
    }
    .option-item:hover{ background:rgba(2,132,199,.06); }
    .option-item input{ margin-right:.5rem; }
    .option-item.selected{
      border-color: rgba(2,132,199,.45);
      background: rgba(2,132,199,.08);
    }
    .option-item.correct{
      border-color: rgba(22,163,74,.55);
      background: rgba(22,163,74,.10);
    }
    .option-item.wrong{
      border-color: rgba(220,38,38,.55);
      background: rgba(220,38,38,.10);
    }
    .question-card.locked .option-item{
      pointer-events:none;
      opacity:.9;
      cursor:default;
    }
    .step{
      background:#f4f6fb;
      border:1px solid rgba(0,0,0,.06);
      border-radius:10px;
      padding:10px 12px;
      margin:10px 0;
    }
    .step-title{ font-weight:600; margin-bottom:6px; }
    .math-chip{
      display:inline-block;
      background:#e9eefc;
      border-radius:10px;
      padding:6px 10px;
      margin:6px 0;
      font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
    }

 
    .seg-progress{
      height:10px;
      display:flex;
      gap: 5%;
      background: transparent;
      border-radius: 999px;
      overflow: visible;
    }
    .seg-progress .seg{
      height:100%;
      border-radius: 999px;
      background: #adb5bd;
      box-shadow: inset 0 0 0 1px rgba(0,0,0,.06);
    }

 
    #explainFab{
      position: fixed;
      left: 50%;
      bottom: 16px;
      transform: translateX(-50%);
      z-index: 1080;
      border-radius: 999px;
      padding: 10px 14px;
      box-shadow: 0 10px 25px rgba(0, 0, 0, .18);
      display: none;
      font-size: 16px;
    }
    @media (max-width: 991.98px){
      #right-col{ display:none !important; }
    }
    @media (min-width: 992px){
      #explainFab{ display:none !important; }
    }

    .modal-body{
      max-height: 70vh;
      overflow:auto;
    }
    .text-muted { padding-bottom: 5px; }


    .bg-success { background-color: rgb(51 241 153) !important; }
    .bg-danger { background-color: rgb(249 33 54) !important; }
    .bg-info { background-color: rgb(18 204 241) !important; }
	  
	 footer {
            background: #1a1d29;
            color: white;
            padding: 3rem 2rem 1.5rem;
        }

        .footer-content {
            max-width: 1200px;
            margin: 0 auto;
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 2rem;
            margin-bottom: 2rem;
        }

        .footer-section h4 {
            margin-bottom: 1rem;
            color: var(--accent-color);
        }

        .footer-section ul {
            list-style: none;
        }

        .footer-section ul li {
            margin-bottom: 0.5rem;
        }

        .footer-section a {
            color: rgba(255, 255, 255, 0.7);
            text-decoration: none;
            transition: color 0.3s ease;
        }

        .footer-section a:hover {
            color: white;
        }

        .footer-bottom {
            text-align: center;
            padding-top: 2rem;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            color: rgba(255, 255, 255, 0.6);
        }
 
	   .hero {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 4rem 2rem;
            text-align: center;
            position: relative;
            overflow: hidden;
        }

        .hero::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><circle cx="50" cy="50" r="2" fill="rgba(255,255,255,0.1)"/></svg>');
            opacity: 0.3;
        }

        .hero-content {
            max-width: 800px;
            margin: 0 auto;
            position: relative;
            z-index: 1;
        }

        .hero h1 {
            font-size: 29px;
            margin-bottom: 1rem;
            font-weight: 700;
        }

        .hero p {
            font-size: 1.2rem;
            margin-bottom: 1rem;
            opacity: 0.95;
        }
	  
.fa-calculator:before {
    content: "\f1ec";
    color: #2196F3;
}