/* ===== PALETA DE COLORES (naranja/oscuro) con fondo gris ===== */
      :root {
        --primary-color: rgba(1, 1, 1, 0.9);
        --secondary-color: #ff8c42;
        --accent-color: #ff6600;
        --light-color: #ffd8b5;
        --text-color: #333;
        --white: #ffffff;
        --black: #000000;
        --orange-gradient: linear-gradient(
          115deg,
          #ff6701,
          #ff9900,
          #fd640b,
          #ff8851,
          #ff9810,
          #ff7951
        );
        --success-color: #4caf50;
        --error-color: #f44336;
        --orange-bg: #b9b8b7;

        /* Fondo gris claro */
        --bg: #e9e9e9;
        --card: var(--white);
        --border: #e0a87a;
        --primary: var(--secondary-color);
        --success: var(--success-color);
        --danger: var(--error-color);
        --text: var(--text-color);
        --dim: #8b5a3c;
        --light: #fff0e0;
        --yellow: #fff1e0;
        --yellow-border: #ffb07c;
      }

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

      body {
        font-family: "Poppins", sans-serif;
        background: var(--bg);
        min-height: 100vh;
        padding-top: 80px;
        padding-bottom: 2rem;
        color: var(--text);
      }

      /* ===== HEADER (menú) ===== */
      .header {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        background-color: var(--primary-color);
        padding: 0 10%;
        display: flex;
        align-items: center;
        justify-content: space-between;
        z-index: 1000;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
        border-bottom: 2px solid var(--secondary-color);
        transition: all 0.3s ease;
      }

      .header:hover {
        box-shadow: 0 6px 16px rgba(0, 0, 0, 0.4);
      }

      .logo {
        font-size: 28px;
        font-weight: 700;
        color: var(--white);
        text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
        letter-spacing: 1px;
      }

      .navigation ul {
        list-style: none;
        margin: 0;
        padding: 0;
      }

      .header .navigation ul li {
        float: left;
        position: relative;
      }

      .header .navigation ul li a {
        font-size: 16px;
        font-weight: 500;
        color: var(--white);
        text-decoration: none;
        padding: 22px 20px;
        display: block;
        transition: all 0.3s ease;
      }

      .header .navigation ul li a:hover {
        background-color: var(--secondary-color);
        transform: translateY(-2px);
        color: var(--black);
      }

      #toggle,
      .header label {
        display: none;
        cursor: pointer;
      }

      .menu {
        width: 28px;
        height: 28px;
        filter: brightness(0) invert(1);
      }

      /* ===== CONTENEDOR PRINCIPAL ===== */
      .exercise-header {
        text-align: center;
        margin-bottom: 2rem;
      }

      .tag {
        display: inline-block;
        font-size: 0.65rem;
        font-weight: 700;
        letter-spacing: 2px;
        text-transform: uppercase;
        color: var(--dim);
        border: 1.5px solid var(--border);
        padding: 3px 14px;
        border-radius: 50px;
        margin-bottom: 0.6rem;
      }

      h1 {
        font-size: clamp(1.5rem, 4vw, 2.2rem);
        font-weight: 900;
        color: var(--text);
      }

      h1 span {
        color: var(--secondary-color);
        background: var(--orange-gradient);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        background-clip: text;
      }

      .subtitle {
        color: var(--dim);
        font-size: 0.82rem;
        margin-top: 0.3rem;
      }

      /* ===== TARJETA PRINCIPAL ===== */
      .card {
        max-width: 800px;
        margin: 0 auto 1.5rem;
        background: var(--card);
        border: 1px solid var(--border);
        border-radius: 16px;
        overflow: hidden;
        box-shadow: 0 4px 24px rgba(255, 102, 0, 0.15);
      }

      .card-header {
        background: var(--light);
        padding: 0.9rem 1.8rem;
        font-size: 0.72rem;
        font-weight: 700;
        color: var(--dim);
        letter-spacing: 2px;
        text-transform: uppercase;
        border-bottom: 1px solid var(--border);
        display: flex;
        align-items: center;
        gap: 0.5rem;
      }

      /* Caja de instrucciones */
      .instr-box {
        background: var(--yellow);
        border: 1.5px solid var(--yellow-border);
        border-radius: 10px;
        padding: 0.8rem 1.2rem;
        margin: 1.2rem 1.5rem;
        font-size: 0.82rem;
        color: #a35100;
        font-weight: 600;
        line-height: 1.5;
      }

      /* ===== TEXTO DE LECTURA ===== */
      .reading {
        padding: 1.2rem 1.8rem 1.5rem;
        font-size: 0.95rem;
        line-height: 2.1;
        color: var(--text);
      }

      .reading h2 {
        font-size: 1.2rem;
        font-weight: 900;
        margin-bottom: 1rem;
        color: var(--text);
        border-left: 5px solid var(--secondary-color);
        padding-left: 12px;
      }

      /* Estilos para los espacios en blanco */
      .blank {
        display: inline-block;
        position: relative;
      }

      .blank input {
        border: none;
        border-bottom: 2px solid var(--primary);
        background: transparent;
        font-family: "Poppins", sans-serif;
        font-size: 0.9rem;
        font-weight: 600;
        color: var(--primary);
        width: 140px;
        outline: none;
        padding: 0 4px 1px;
        transition:
          border-color 0.2s,
          background 0.2s;
        text-align: center;
      }

      .blank input:focus {
        border-color: var(--accent-color);
      }

      .blank input.correct {
        border-color: var(--success);
        color: var(--success);
        background: #e6f4ea;
        border-radius: 4px;
      }

      .blank input.wrong {
        border-color: var(--danger);
        color: var(--danger);
        background: #ffebee;
        border-radius: 4px;
      }

      .blank input.revealed {
        border-color: var(--dim);
        color: var(--dim);
        font-style: italic;
        background: #f5f5f5;
      }

      .blank input:disabled {
        opacity: 0.8;
        cursor: not-allowed;
      }

      .blank-num {
        font-size: 0.6rem;
        font-weight: 700;
        color: var(--dim);
        vertical-align: super;
        margin-right: 2px;
      }

      /* ===== SECCIÓN VERDADERO/FALSO (generada dinámicamente) ===== */
      .tf-section {
        padding: 1.2rem 1.8rem 1.5rem;
        border-top: 1px solid var(--border);
      }

      .tf-title {
        font-size: 0.72rem;
        font-weight: 700;
        letter-spacing: 2px;
        text-transform: uppercase;
        color: var(--dim);
        margin-bottom: 1rem;
        padding-bottom: 0.4rem;
        border-bottom: 1px solid var(--border);
      }

      .tf-item {
        display: flex;
        align-items: center;
        gap: 1rem;
        padding: 0.6rem 0.8rem;
        border-radius: 8px;
        margin-bottom: 0.4rem;
        border: 1.5px solid transparent;
        transition: all 0.2s;
      }

      .tf-item:hover {
        background: #fae1ce;
      }

      .tf-item.correct {
        background: #e6f4ea;
        border-color: #b8e0c0;
      }

      .tf-item.wrong {
        background: #ffebee;
        border-color: #ffb3b3;
      }

      .tf-num {
        width: 24px;
        height: 24px;
        border-radius: 50%;
        background: var(--border);
        color: var(--dim);
        font-size: 0.7rem;
        font-weight: 700;
        display: flex;
        align-items: center;
        justify-content: center;
        flex-shrink: 0;
      }

      .tf-item.correct .tf-num {
        background: var(--success);
        color: #fff;
      }

      .tf-item.wrong .tf-num {
        background: var(--danger);
        color: #fff;
      }

      .tf-text {
        flex: 1;
        font-size: 0.9rem;
        font-weight: 600;
        line-height: 1.3;
      }

      .tf-btns {
        display: flex;
        gap: 0.4rem;
        flex-shrink: 0;
      }

      .tf-btn {
        width: 40px;
        height: 34px;
        border: 1.5px solid var(--border);
        border-radius: 6px;
        background: var(--light);
        font-family: "Poppins", sans-serif;
        font-size: 0.8rem;
        font-weight: 700;
        color: var(--dim);
        cursor: pointer;
        transition: all 0.15s;
      }

      .tf-btn:hover:not(:disabled) {
        border-color: var(--primary);
        color: var(--primary);
        background: #ffeadb;
      }

      .tf-btn:disabled {
        opacity: 0.5;
        cursor: not-allowed;
      }

      .tf-btn.active-t {
        background: var(--primary);
        color: #fff;
        border-color: var(--primary);
      }

      .tf-btn.active-f {
        background: var(--danger);
        color: #fff;
        border-color: var(--danger);
      }

      /* ===== BARRA INFERIOR ===== */
      .bottom-bar {
        padding: 1rem 1.8rem;
        border-top: 1px solid var(--border);
        display: flex;
        align-items: center;
        justify-content: space-between;
        flex-wrap: wrap;
        gap: 0.6rem;
        background: var(--light);
      }

      .score-txt {
        font-size: 0.9rem;
        font-weight: 700;
        color: var(--dim);
      }

      .score-txt span {
        color: var(--secondary-color);
        font-size: 1.2rem;
      }

      .btn {
        border: none;
        border-radius: 50px;
        padding: 0.5rem 1.5rem;
        font-family: "Poppins", sans-serif;
        font-size: 0.8rem;
        font-weight: 700;
        cursor: pointer;
        transition: all 0.18s;
      }

      .btn-outline {
        background: transparent;
        border: 1.5px solid var(--border);
        color: var(--dim);
      }

      .btn-outline:hover:not(:disabled) {
        border-color: var(--primary);
        color: var(--primary);
        background: #ffeadb;
      }

      .btn-outline:disabled {
        opacity: 0.5;
        cursor: not-allowed;
      }

      .btn-reset {
        background: var(--dim);
        color: white;
        border: none;
      }

      .btn-reset:hover:not(:disabled) {
        background: #a5673f;
      }

      /* ===== BANNER DE RESULTADOS ===== */
      .result-banner {
        display: none;
        margin: 0 1.5rem 1.2rem;
        padding: 0.9rem 1.2rem;
        border-radius: 10px;
        text-align: center;
        font-weight: 700;
        font-size: 0.95rem;
      }

      .result-banner.show {
        display: block;
      }

      .result-banner.good {
        background: #e6f4ea;
        border: 1.5px solid #b8e0c0;
        color: var(--success);
      }

      .result-banner.ok {
        background: var(--yellow);
        border: 1.5px solid var(--yellow-border);
        color: #a35100;
      }

      /* ===== MEDIA QUERIES ===== */
      @media (max-width: 950px) {
        .header label {
          display: initial;
        }

        .header {
          padding: 12px 5%;
        }

        .header .navigation {
          position: absolute;
          top: 100%;
          left: 0;
          right: 0;
          background: var(--primary-color);
          display: none;
          border-radius: 0 0 12px 12px;
          box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
        }

        .header .navigation ul li {
          width: 100%;
        }

        .header .navigation ul li a {
          padding: 15px 20px;
          font-size: 18px;
        }

        #toggle:checked ~ .navigation {
          display: block;
          animation: slideDown 0.4s ease-out;
        }

        @keyframes slideDown {
          from {
            opacity: 0;
            transform: translateY(-20px);
          }
          to {
            opacity: 1;
            transform: translateY(0);
          }
        }
      }

      @media (max-width: 600px) {
        .reading {
          padding: 1rem;
          font-size: 0.85rem;
        }
        .blank input {
          width: 100px;
        }
        .tf-section {
          padding: 1rem;
        }
        .tf-text {
          font-size: 0.8rem;
        }
        .bottom-bar {
          flex-direction: column;
          align-items: stretch;
        }
        .btn {
          width: 100%;
        }
      }