.site-logo {
  position: fixed;
  top: 12px;
  left: 16px;
  font-size: 18px;
  font-weight: bold;
  color: #00c6ff;
  text-decoration: none;
  z-index: 999;
  font-family: monospace;
  background-color: rgba(255, 255, 255, 0.9);
  padding: 6px 12px;
  border-radius: 8px;
  box-shadow: 0 0 5px #00c6ff;
  transition: 0.3s ease;
  max-width: 40vw;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.site-logo:hover {
  color: #e52e71;
  box-shadow: 0 0 10px #e52e71;
}

@media (max-width: 600px) {
  .site-logo {
    font-size: 14px;
    top: 10px;
    left: 10px;
    padding: 5px 10px;
    max-width: 70vw;
  }
}
body {

      font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
      background: linear-gradient(to right, #f0f2f5, #c8e6c9);
      padding: 40px;
      display: flex;
      justify-content: center;
}
    .container {
      max-width: 600px;
      width: 100%;
      margin: auto;
      background: white;
      padding: 20px;
      border-radius: 12px;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
      box-sizing: border-box;
    }

    @media (max-width: 480px) {
      .container {
        padding: 12px;
      }
    }

    h2 {
      text-align: center;
      margin-bottom: 24px;
      color: #2e7d32;
      font-size: 20px;
    }

    .question p {
      margin-bottom: 16px;
      line-height:  1.5;
    }

    .option-btn {
      padding: 12px;
      width: 100%;
      border: none;
      background: #ccc;
      color: black;
      border-radius: 6px;
      cursor: pointer;
      font-size: 16px;
      transition: background 0.3s ease;
      text-align: left;
      position: relative;
      padding-left: 48px;
    }

    .option-btn::before {
      content: attr(data-label);
      position: absolute;
      left: 12px;
      top: 50%;
      transform: translateY(-50%);
      width: 28px;
      height: 28px;
      border-radius: 50%;
      background: #fff;
      border: 2px solid #0b0b0b;
      color: #060606;
      font-weight: bold;
      font-size: 14px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .option-btn:hover:not(:disabled) {
      background: #bbb;
    }

    .correct {
      background-color: #4caf50 !important;
      color: white;
      animation: shine 0s ease;
    }

    .incorrect {
      background-color: #e53935 !important;
      color: white;
      animation: shake 0s ease;
    }

    .options-grid {
      display: flex;
      flex-direction: column;
      gap: 10px;
      width: 100%;
    }

    @keyframes shake {
      0% { transform: translateX(0); }
      25% { transform: translateX(-4px); }
      50% { transform: translateX(4px); }
      75% { transform: translateX(-4px); }
      100% { transform: translateX(0); }
    }

    @keyframes shine {
         0% { transform: translateX(0); }
      25% { transform: translateX(-4px); }
      50% { transform: translateX(4px); }
      75% { transform: translateX(-4px); }
      100% { transform: translateX(0); }
      0% { box-shadow: 0 0 0px #4caf50; }
      50% { box-shadow: 0 0 12px #4caf50; }
      100% { box-shadow: 0 0 0px #4caf50; }
    }

    .question {
      animation: fadeIn 0s ease;
      margin-bottom: 20px;
    }

    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(10px); }
      to { opacity: 1; transform: translateY(0); }
    }

    button:disabled {
      cursor: not-allowed;
      opacity: 0.7;
    }

    .nav-buttons {
      display: flex;
      justify-content: space-between;
      margin-top: 20px;
    }

    .nav-buttons button {
      width: 48%;
      font-weight: bold;
      background-color: #2e7d32;
      color: white;
      transition: background 0.3s;
      border-radius: 8px;
      font-size: 16px;
      padding: 12px 16px;
      border: none;
    }

    .nav-buttons button:hover {
      background-color: #1b5e20;
    }

    button#toc-toggle,
    #toc button {
      border-radius: 8px;
      font-size: 16px;
      padding: 10px 14px;
      background-color: #607d8b;
      color: white;
      border: none;
      cursor: pointer;
    }

    #toc button:hover,
    button#toc-toggle:hover {
      background-color: #455a64;
    }
    .question-image {
  text-align: center;
  margin: 16px 0;
}
.question-image img {
  max-width: 40%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 0 6px rgba(0, 0, 0, 0.2);
}
.image-row {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin: 16px 0;
  flex-wrap: wrap;
}

.image-row img {
  width: 40%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 0 6px rgba(0, 0, 0, 0.2);
}
.zoomable {
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: zoom-in;
  z-index: 1;
  position: relative;
}

.zoomable.zoomed {
  transform: scale(2.5);
  cursor: zoom-out;
  z-index: 9999;
  box-shadow: 0 0 12px rgba(0, 0, 0, 0.5);
}
@media (max-width: 600px) {
  .container {
    max-width: 95vw;
    padding: 16px 12px;
  }
}

/* ===== Box thống kê dưới mục lục ===== */
#status-box {
  background: linear-gradient(180deg, #ffffff, #f7fff7);
  border-radius: 10px;
  padding: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.06);
  margin: 12px auto;
  max-width: 500px;
}

.status-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 0;
  gap: 8px;
}

.status-label {
  font-weight: 600;
  color: #2e7d32;
}

.status-value {
  font-weight: 700;
  color: #0b3d02;
}

/* Cho điện thoại */
@media (max-width: 600px) {
  #status-box {
    padding: 10px;
    font-size: 14px;
  }
  .status-label {
    font-size: 14px;
  }
  .status-value {
    font-size: 14px;
  }
}
/* ===== TOC hiển thị 10 ô / hàng ===== */
#toc {
  display: none; 
  grid-template-columns: repeat(10, 1fr);
  gap: 6px;
  justify-items: center;
}

#toc.show {
  display: grid; 
}

#toc button {
  width: 100%;
  max-width: 40px;
  aspect-ratio: 1 / 1;
  text-align: center;
  padding: 0;
  font-weight: bold;
  border-radius: 6px;
  border: none;
  cursor: pointer;
}