body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f0f2f5;
}

.container {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    width: 350px;
}

.input-group {
    margin-bottom: 10px;
}

input {
    width: 100%;
    padding: 12px;
    box-sizing: border-box;
    border: 2px solid #ddd;
    border-radius: 6px;
    outline: none;
    transition: border-color 0.3s;
}

input:focus {
    border-color: #007bff;
}

/* The Progress Bar Container */
.strength-meter {
    height: 8px;
    background-color: #eee;
    border-radius: 4px;
    margin: 15px 0 5px 0;
    overflow: hidden;
}

/* The actual bar that grows */
#strength-bar {
    height: 100%;
    width: 0%;
    transition: width 0.4s ease, background-color 0.4s ease;
}

#strength-text {
    font-size: 0.9rem;
    margin-bottom: 20px;
}

.requirements {
    list-style: none;
    padding: 0;
    font-size: 0.8rem;
    color: #666;
}

.requirements li.valid {
    color: #28a745;
    text-decoration: line-through;
}