:root {
  --bg: #0f0f14;
  --panel: #161622;
  --accent: #7c7cff;
  --accent-soft: #5a5ad6;
  --text: #ffffff;
  --muted: #a0a0c0;
  --border: #2a2a40;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 20px;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", system-ui, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* TÍTULO */
h1 {
  margin-bottom: 20px;
  font-weight: 600;
  letter-spacing: 0.5px;
}

/* PAINÉIS */
.controls,
.sizes {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 16px;
  margin-bottom: 12px;
}

/* SELECT */
select {
  appearance: none;
  background: #1d1d2f;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 36px 8px 12px;
  font-size: 14px;
  cursor: pointer;
  background-image:
    linear-gradient(45deg, transparent 50%, var(--accent) 50%),
    linear-gradient(135deg, var(--accent) 50%, transparent 50%);
  background-position:
    calc(100% - 18px) 50%,
    calc(100% - 12px) 50%;
  background-size: 6px 6px;
  background-repeat: no-repeat;
}

select:hover {
  border-color: var(--accent);
}

/* TAMANHOS */
.sizes {
  display: flex;
  gap: 20px;
}

.sizes h3 {
  margin: 0 0 6px;
  font-size: 14px;
  color: var(--muted);
}

/* INPUTS NUMÉRICOS */
input[type="number"] {
  width: 48px;
  height: 32px;
  text-align: center;
  background: #1d1d2f;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
}

input[type="number"]:focus {
  outline: none;
  border-color: var(--accent);
}

/* MATRIZES */
.matrices {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 20px 0;
}

.matrix {
  background: var(--panel);
  padding: 10px;
  border-radius: 12px;
  display: grid;
  gap: 6px;
}

.matrix input {
  width: 42px;
  height: 36px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: #1c1c2b;
  color: var(--text);
  font-size: 14px;
}

.matrix input:focus {
  outline: none;
  border-color: var(--accent);
}

/* SÍMBOLO DA OPERAÇÃO */
#opSymbol {
  font-size: 28px;
  font-weight: 600;
  color: var(--accent);
  user-select: none;
}

/* BOTÃO */
button {
  margin-top: 10px;
  padding: 10px 24px;
  font-size: 15px;
  font-weight: 500;
  color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-soft));
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: transform 0.1s ease, box-shadow 0.1s ease;
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(124, 124, 255, 0.4);
}

button:active {
  transform: translateY(0);
  box-shadow: none;
}

/* RESULTADO */
#result {
  margin-top: 16px;
  background: #10101a;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 14px;
  font-size: 14px;
  line-height: 1.4;
  min-width: 180px;
  max-width: 100%;
  white-space: pre;
  text-align: left;
}

/* RESPONSIVO */
@media (max-width: 600px) {
  .sizes {
    flex-direction: column;
    gap: 10px;
  }

  .matrices {
    flex-direction: column;
  }
}