:root {
  --bg: #071428;
  --card: #0e1833;
  --accent: #60A5FA;
  --muted: #c7e8ff;
  --border: rgba(255,255,255,0.06);
}

body {
  margin: 0;
  font-family: "Inter", Arial, sans-serif;
  background: var(--bg);
  color: #e2f2ff;
}

header {
  padding: 28px;
  text-align: center;
  background: rgba(255,255,255,0.02);
  border-bottom: 1px solid var(--border);
}

h1 {
  color: var(--accent);
  font-size: 2rem;
  margin: 0;
}

nav {
  margin-top: 16px;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

nav button {
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 14px;
  cursor: pointer;
  color: var(--muted);
}

nav button.active {
  background: var(--accent);
  color: #001;
  border-color: var(--accent);
  font-weight: bold;
}

.container {
  max-width: 1250px;
  margin: 28px auto;
  padding: 22px;
}

.section {
  display: none;
  background: var(--card);
  border-radius: 14px;
  border: 1px solid var(--border);
  padding: 24px;
}

.section.active {
  display: block;
}

.card {
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border);
  padding: 16px;
  border-radius: 12px;
  margin-top: 16px;
}

.solution {
  display: none;
  background: rgba(0,0,0,0.5);
  padding: 14px;
  margin-top: 10px;
  border-radius: 10px;
  white-space: pre-wrap;
  color: #d5ffff;
  font-size: 17px;
}

button.solution-btn {
  margin-top: 6px;
  background: var(--accent);
  padding: 6px 10px;
  color: black;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

code {
  display: block;
  background: rgba(0,0,0,0.43);
  padding: 10px;
  border-radius: 8px;
  white-space: pre;
  overflow-x: auto;
}

.btn-volver {
    display: inline-block;
    padding: 10px 20px;
    
    color: #f8f9fb;
    font-weight: 600;
    text-decoration: none;       
    transition: 0.25s ease;    
}

.btn-volver:hover {    
    color: #00e5ff;
    transform: translateY(-2px);    
}

/* wa section Starts */
.btn-wa {
    position: fixed;
        width: 50px;
        height: 50px;
        bottom: 10px;
        right: 10px;
        background: transparent;
        z-index: 5000;

}

.img-responsive-wa {
        width: 50px;
        height: 50px;
        bottom: 10px;
        left: 10px;
}

@media only screen and (min-width: 320px) and (max-width: 768px) {
  .btn-wa {
                  width: 50px;
            height: 50px;
  
  }
}
/* wa section Ends */


/* FOOTER */
footer {
  text-align: center;
  margin-top: 50px;
  padding: 20px;
  color: #8896ad;
  font-size: .85rem;
  opacity: .7;
}

/* Boton youtube starts */
.btn-youtube {
  margin-top: 17px;  
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: #ff0000;
  color: #fff;
  padding: 4px 7px;
  border-radius: 5px;
  text-decoration: none;
  font-weight: 600;
  transition: 0.2s;
  font-size: 13px;
}
.btn-youtube:hover {
  background: #cc0000;
}
.btn-youtube i {
  font-size: 20px;
}
/* Boton youtube ends */