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

body {
    font-family: 'Poppins', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
    transition: background 0.6s ease, color 0.6s ease;
}

/* Fondo animado */
.background {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: linear-gradient(120deg, #6a11cb, #2575fc, #ff416c);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    z-index: -2;
}

@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* Burbujas */
.bubbles {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    overflow: hidden;
    z-index: -1;
}

.bubbles span {
    position: absolute;
    bottom: -100px;
    width: 40px; height: 40px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 50%;
    animation: rise 12s infinite ease-in;
    filter: blur(1px);
}

@keyframes rise {
    0% { transform: translateY(0) scale(1); opacity: 1; }
    100% { transform: translateY(-120vh) scale(1.3); opacity: 0; }
}

/* Loader */
.loader {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: #0a0a0a;
    display: flex;
    justify-content: center;
    align-items: center;
    color: #fff;
    font-size: 1.5rem;
    animation: fadeOut 1s ease 2.5s forwards;
    z-index: 99;
}

@keyframes fadeOut {
    to { opacity: 0; visibility: hidden; }
}

/* Contenido */
.container {
    text-align: center;
    background: rgba(255,255,255,0.1);
    backdrop-filter: blur(15px);
    padding: 50px 60px;
    border-radius: 25px;
    box-shadow: 0 15px 40px rgba(0,0,0,0.3);
    color: #fff;
    animation: fadeIn 1s ease forwards;
    opacity: 0;
}

@keyframes fadeIn {
    to { opacity: 1; }
}

h1 {
    font-size: 2.6rem;
    margin-bottom: 10px;
    text-shadow: 1px 1px 6px rgba(0,0,0,0.3);
}

#greeting {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 30px;
}

.buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 20px;
}

.buttons a {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 28px;
    font-weight: 600;
    color: #fff;
    text-decoration: none;
    border-radius: 50px;
    background: linear-gradient(45deg, #ff416c, #ff4b2b);
    transition: all 0.3s ease;
    box-shadow: 0 5px 20px rgba(0,0,0,0.2);
}

.buttons a:hover {
    transform: translateY(-5px) scale(1.05);
    background: linear-gradient(45deg, #ff4b2b, #ff416c);
    box-shadow: 0 10px 30px rgba(0,0,0,0.4);
}

/* Botón de modo oscuro */
.theme-toggle {
    position: absolute;
    top: 25px;
    right: 25px;
    background: rgba(255,255,255,0.2);
    backdrop-filter: blur(10px);
    border: none;
    border-radius: 50%;
    width: 45px; height: 45px;
    cursor: pointer;
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    transform: rotate(20deg);
    background: rgba(255,255,255,0.3);
}

/* Modo oscuro */
body.dark {
    color: #111;
    background: #eaeaea;
}

body.dark .container {
    background: rgba(255,255,255,0.85);
    color: #111;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

body.dark .buttons a {
    color: #fff;
    background: linear-gradient(45deg, #2575fc, #6a11cb);
}

body.dark .buttons a:hover {
    background: linear-gradient(45deg, #6a11cb, #2575fc);
}

@media(max-width: 600px){
    .container { padding: 30px; }
    h1 { font-size: 2rem; }
    .buttons a { padding: 12px 22px; font-size: 1rem; }
}