body { font-family: sans-serif; max-width: 800px; margin: 20px auto; padding: 20px; background: #f4f4f9; }
.container { background: white; padding: 30px; border-radius: 10px; box-shadow: 0 4px 10px rgba(0,0,0,0.1); }
input { width: 100%; padding: 10px; margin: 10px 0; border: 1px solid #ddd; border-radius: 5px; box-sizing: border-box; }
button { background: #2980b9; color: white; padding: 10px 20px; border: none; cursor: pointer; border-radius: 5px; width: 100%; }
button:disabled { background: #ccc; }
#resultado { margin-top: 20px; padding: 15px; border-left: 5px solid #333; background: #eee; display: none; }
.error { color: red; font-weight: bold; }