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

:root {
  /* Tema oscuro (default) */
  --bg-primary: #000000;
  --text-primary: #ffffff;
  --shadow-color: rgba(0, 0, 0, 0.5);
}

[data-theme="light"] {
  --bg-primary: #ffffff;
  --text-primary: #000000;
  --shadow-color: rgba(0, 0, 0, 0.1);
}

html, body {
  height: 100%;
  font-family: "Inter", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  overflow: hidden;
  transition: background-color 0.3s ease, color 0.3s ease;
}

canvas#bg {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 0;
  width: 100%;
  height: 100%;
}

/* Botón de tema CENTRADO */
.theme-toggle {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 1000;
  background: var(--bg-primary);
  border: 1px solid var(--text-primary);
  border-radius: 50%;
  width: 80px;
  height: 80px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  transition: all 0.3s ease;
  box-shadow: 0 8px 32px var(--shadow-color);
  opacity: 0.9;
}

.theme-toggle:hover {
  transform: translate(-50%, -50%) scale(1.1);
  opacity: 1;
  box-shadow: 0 12px 40px var(--shadow-color);
}

[data-theme="light"] .theme-icon {
  content: "☀️";
}

/* Efectos de aparición */
.theme-toggle {
  animation: buttonAppear 0.8s ease-out;
}

@keyframes buttonAppear {
  from {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.8);
  }
  to {
    opacity: 0.9;
    transform: translate(-50%, -50%) scale(1);
  }
}

/* Crédito abajo */
.credit {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1000;
  font-family: "Inter", sans-serif;
  font-size: 0.9rem;
  opacity: 0.7;
  transition: all 0.3s ease;
}

.credit a {
  color: var(--text-primary);
  text-decoration: none;
  padding: 8px 16px;
  border-radius: 20px;
  background: rgba(0, 0, 0, 0.1);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

[data-theme="light"] .credit a {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(0, 0, 0, 0.1);
}

.credit a:hover {
  opacity: 1;
  transform: translateY(-2px);
}

/* Efecto de aparición para el crédito */
.credit {
  animation: creditAppear 1s ease-out 0.5s both;
}

@keyframes creditAppear {
  from {
    opacity: 0;
    transform: translateX(-50%) translateY(20px);
  }
  to {
    opacity: 0.7;
    transform: translateX(-50%) translateY(0);
  }
}