:root{--bg-color: #f4f4f4;--bg-color-dark: #000000ec;--text-color: #333;--text-color-dark: #333;--border-shadow: rgba(0, 78, 245, .747);--border-shadow-dark: rgb(255, 0, 0);--container-bg: #fff;--container-bg-dark: #2c2c2c}*{margin:0;padding:0;box-sizing:border-box;font-family:Arial,sans-serif}body{line-height:1.6;background-color:var(--bg-color);color:var(--text-color);padding:20px;transition:background-color .3s ease,color .3s ease}body.dark{line-height:1.6;background-color:var(--bg-color-dark);color:var(--text-color-dark);padding:20px;transition:background-color .3s ease,color .3s ease}header,main,footer{max-width:1050px;margin:0 auto 20px;padding:20px;background:var(--container-bg);border-radius:8px;box-shadow:0 2px 5px var(--border-shadow);transition:background-color .3s ease,box-shadow .3s ease}header.dark,main.dark,footer.dark{box-shadow:0 2px 5px var(--border-shadow-dark)}header{display:flex;flex-direction:column;align-items:flex-start;position:relative}.main-content{flex:2}.center-text{text-align:center}.theme-btn{position:absolute;right:20px;top:20px;background:none;border:none;font-size:1.5rem;cursor:pointer;z-index:10}h1{color:#2c3e50;margin-bottom:10px}nav ul{display:flex;justify-content:center;list-style:none;gap:15px;margin-top:15px}nav a{text-decoration:none;color:#3498db;font-weight:700}section{margin:20px 0}p{text-align:justify}h2{color:#2c3e50;border-bottom:1px solid #eee;padding-bottom:5px;margin-bottom:10px}h4{color:#2c3e50;text-align:center;padding-bottom:5px;margin-bottom:10px}footer{text-align:center;font-size:.9em;color:#7f8c8d}.iconosFooter{text-align:end}.icon-link{padding:.5em}@media(max-width:600px){body{padding:10px}nav ul{flex-direction:column;gap:5px}}.dropdown{position:relative}.dropdown-menu{display:none;margin-top:10px;padding-top:10px;position:absolute;top:100%;left:0;background:#444;min-width:160px;box-shadow:0 8px 16px #0003}.dropdown:hover .dropdown-menu{display:block}.dropdown-menu:before{content:"";position:absolute;top:-10px;left:20px;width:100%;height:10px;background:transparent}.dropdown-menu li{padding:10px}.dropdown-menu a:hover{background:#007bff}.padding-left{padding-left:20px}.aling-center{text-align:center}.aling-left{text-align:left}.sidebar{flex:1;background:#f8f9fa;padding:20px;border-radius:8px;box-shadow:0 2px 5px var(--border-shadow);margin-left:20px}.sidebar.dark{box-shadow:0 2px 5px var(--border-shadow-dark)}.sidebar h3{color:#2c3e50;border-bottom:1px solid #eee;padding-bottom:10px;margin-bottom:15px}.sidebar ul{padding-left:20px;margin-bottom:20px}.sidebar li{margin-bottom:8px}.highlight-box{background:#e3f2fd;padding:15px;border-radius:8px;margin-top:20px}.signup-button{background-color:#3498db;color:#fff;border:none;padding:10px 15px;border-radius:5px;cursor:pointer;margin-top:10px;width:100%}.signup-button:hover{background-color:#2980b9}@media(max-width:768px){.two-column-layout,.three-column-layout{flex-direction:column}.sidebar{margin-top:20px}}.two-column-layout{display:flex;gap:30px}.three-column-layout{display:flex}.timeline{position:relative;list-style:none;padding-left:40px;margin:20px 0}.timeline:before{content:"";position:absolute;top:0;left:15px;width:2px;height:100%;background-color:#333}.timeline li{position:relative;margin-bottom:30px}.timeline li:before{content:"";position:absolute;left:-34px;top:5px;width:16px;height:16px;background-color:#fff;border:2px solid #333;border-radius:50%}.timeline .year{font-weight:700;margin-bottom:5px}.timeline .desc{color:#555}.todo-container{background-color:var(--container-bg);color:var(--text-color);border-radius:12px;padding:1.5rem 2rem;box-shadow:0 0 10px var(--border-shadow);transition:all .3s ease}.dark-mode .todo-container{background-color:var(--container-bg-dark);color:var(--text-color-dark);box-shadow:0 0 10px var(--border-shadow-dark)}.todo-container h2{font-size:1.6rem;font-weight:700;margin-bottom:1rem;border-bottom:2px solid var(--border-shadow);padding-bottom:.5rem}.todo-description{margin-bottom:1rem;font-size:.95rem;color:#555}.dark-mode .todo-description{color:#ccc}.todo-list{list-style:none;padding-left:0}.todo-item{background-color:#f9f9f9;border-radius:8px;padding:.7rem 1rem;margin-bottom:.6rem;display:flex;align-items:center;justify-content:space-between;box-shadow:0 2px 5px #0000000d;transition:transform .2s ease,background-color .3s}.todo-item:hover{transform:translateY(-2px);background-color:#eef3ff}.dark-mode .todo-item{background-color:#3b3b3b}.dark-mode .todo-item:hover{background-color:#4a4a4a}.todo-item:before{content:"✔️";margin-right:.5rem;font-size:1rem}.todo-item a{color:var(--border-shadow);text-decoration:none;font-weight:600}.todo-item a:hover{text-decoration:underline}body,.todo-container,.todo-item{transition:background-color .3s,color .3s,box-shadow .3s}