:root {
  --primary: #b87333; /* Cobre base */
  --primary-light: #cd7f32; /* Cobre claro */
  --primary-dark: #8b4513; /* Cobre escuro/oxidado */
  --accent: #ffd700; /* Dourado envelhecido */
  --warning: #a52a2a; /* Vermelho oxidado */
  --bg-dark: #2a1810; /* Marrom muito escuro */
  --bg-darker: #1a0f0a; /* Quase preto com tom marrom */
  --text: #d4af37; /* Dourado suave para texto */
  --text-faded: #98816b; /* Texto secundário */
  --rust: #8b4513; /* Ferrugem */
  --metal: #707070; /* Metal envelhecido */
}

body {
  font-family: 'Share Tech Mono', monospace;
  background-color: var(--bg-dark);
  color: var(--text);
  line-height: 1.6;
  margin: 0;
  padding: 20px;
  background-image:
    radial-gradient(
      circle at 50% 50%,
      rgba(184, 115, 51, 0.1) 0%,
      transparent 80%
    ),
    repeating-linear-gradient(
      45deg,
      rgba(139, 69, 19, 0.05) 0px,
      rgba(139, 69, 19, 0.05) 1px,
      transparent 1px,
      transparent 2px
    );
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
  position: relative;
}

.document-header {
  background-color: var(--bg-darker);
  border: 2px solid var(--primary);
  padding: 30px;
  margin-bottom: 30px;
  position: relative;
  box-shadow:
    0 0 15px rgba(184, 115, 51, 0.2),
    inset 0 0 30px rgba(139, 69, 19, 0.3);
}

.document-stamp {
  position: absolute;
  top: -15px;
  right: 30px;
  background-color: var(--warning);
  color: var(--text);
  padding: 5px 15px;
  transform: rotate(5deg);
  border: 2px solid var(--primary-light);
  box-shadow: 2px 2px 5px rgba(0, 0, 0, 0.3);
  z-index: 2;
  font-weight: bold;
}

.document-date {
  font-size: 0.9em;
  color: var(--text-faded);
  margin-bottom: 20px;
  border-bottom: 1px solid var(--primary);
  padding-bottom: 10px;
}

.censored {
  background-color: var(--primary-dark);
  color: transparent;
  padding: 0 5px;
  margin: 0 2px;
  user-select: none;
}

.document-intro {
  font-size: 1.1em;
  line-height: 1.6;
  margin: 20px 0;
  color: var(--text);
}

.warning-box {
  border: 1px solid var(--warning);
  padding: 15px;
  margin: 20px 0;
  background-color: rgba(165, 42, 42, 0.1);
  position: relative;
}

.warning-box::before {
  content: '⚠ ATENÇÃO';
  position: absolute;
  top: -10px;
  left: 10px;
  background-color: var(--bg-darker);
  padding: 0 10px;
  color: var(--warning);
  font-weight: bold;
}

.metadata {
  display: flex;
  justify-content: space-between;
  margin-top: 20px;
  padding-top: 20px;
  border-top: 1px dashed var(--primary);
  font-size: 0.9em;
  color: var(--text-faded);
}

.exercise-list {
  list-style: none;
  padding: 0;
}

.exercise-item {
  background-color: var(--bg-darker);
  border: 1px solid var(--primary);
  padding: 20px;
  margin-bottom: 20px;
  position: relative;
  box-shadow:
    0 0 10px rgba(184, 115, 51, 0.1),
    inset 0 0 20px rgba(139, 69, 19, 0.2);

  .exercise-number {
    color: var(--primary-light);
    font-size: 1.4em;
    font-weight: bold;
    margin-bottom: 15px;
    display: inline-block;
    padding: 5px 10px;
    border: 1px solid var(--primary);
    background-color: rgba(184, 115, 51, 0.1);
  }

  .context {
    color: var(--text-faded);
    font-style: italic;
    margin-bottom: 15px;
    padding: 10px;
    border-left: 3px solid var(--rust);
    background-color: rgba(139, 69, 19, 0.1);
  }

  .hint {
    background-color: rgba(212, 175, 55, 0.1);
    border-left: 3px solid var(--accent);
    padding: 10px;
    margin: 15px 0;
    color: var(--text-faded);
  }

  details {
    margin-top: 20px;
    border: 1px solid var(--primary);
  }

  summary {
    padding: 10px;
    background-color: rgba(184, 115, 51, 0.1);
    cursor: pointer;
    font-weight: bold;
    color: var(--primary-light);
  }

  summary:hover {
    background-color: rgba(184, 115, 51, 0.2);
    color: var(--accent);
  }

  .solution {
    background-color: rgba(26, 15, 10, 0.8);
    padding: 20px;
    border-top: 1px solid var(--primary);
  }

  @keyframes flicker {
    0% {
      opacity: 1;
    }
    50% {
      opacity: 0.95;
    }
    100% {
      opacity: 1;
    }
  }

  .document-header {
    animation: flicker 2s infinite;
  }

  @keyframes metallic-shine {
    0% {
      box-shadow:
        0 0 5px var(--primary),
        inset 0 0 10px rgba(184, 115, 51, 0.3);
    }
    50% {
      box-shadow:
        0 0 15px var(--primary-light),
        inset 0 0 20px rgba(184, 115, 51, 0.5);
    }
    100% {
      box-shadow:
        0 0 5px var(--primary),
        inset 0 0 10px rgba(184, 115, 51, 0.3);
    }
  }

  .exercise-item:hover {
    animation: metallic-shine 3s infinite;
  }

  .page-number {
    text-align: right;
    color: var(--text-faded);
    margin-top: 20px;
    font-size: 0.9em;
    border-top: 1px solid var(--primary);
    padding-top: 10px;
  }

  /* Estilo para fórmulas matemáticas */
  .mjx-chtml {
    color: var(--text) !important;
  }
}