.container {
    max-width: 400px;
    margin: 50px auto;
    padding: 20px;
    background: rgba(0, 0, 0, 0.8);
    border: 2px solid #00ff00;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 255, 0, 0.5);
}

h1 {
    text-align: center;
    color: #00ff00;
    text-shadow: 0 0 10px #00ff00;
}

.input-group {
    position: relative;
    margin-bottom: 20px;
}

.input-group i {
    position: absolute;
    left: 10px;
    top: 12px;
    color: #00ff00;
}

input {
    width: 100%;
    padding: 10px 10px 10px 40px;
    background: #111;
    border: 1px solid #00ff00;
    color: #fff;
    border-radius: 5px;
    transition: box-shadow 0.3s;
}

input:focus {
    outline: none;
    box-shadow: 0 0 10px #00ff00;
}

.checkbox-group {
    display: flex;
    align-items: center;
    margin-bottom: 20px;
    text-align: left;
}

.checkbox-input {
    appearance: none;
    width: 10px;
    height: 18px;
    margin-right: 12px;
    cursor: pointer;
    position: relative;
    border: 3px solid #00ff00;
    background: transparent;
    transition: all 0.3s ease;
}

.checkbox-input:checked {
    border: none;
    background: #00ff00;
    animation: circularFill 0.4s ease;
}

.checkbox-input:checked::before {
    position: absolute;
}

@keyframes circularFill {
    0% {transform: scale(0);}
    50% {transform: scale(1.2);}
    100% {transform: scale(1);}
}

button {
    width: 100%;
    padding: 10px;
    background: #00ff00;
    border: none;
    color: #000;
    font-weight: bold;
    border-radius: 5px;
    cursor: pointer;
    transition: box-shadow 0.3s;
}

button:hover {
    box-shadow: 0 0 15px #00ff00;
}

button i {
    margin-right: 5px;
}

p {
    text-align: center;
    color: #fff;
}

p a {
    color: #00ff00;
    text-decoration: none;
}

p a:hover {
    text-decoration: underline;
}