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

body {
    font-family: 'Arial', sans-serif;
    background-color: #0d1117; 
    color: #c9d1d9; 
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100vw;
    height: 100vh;
}

/* Container Styling */
.container {
    width: 90%;
    max-width: 500px;
    background-color: #161b22; 
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0px 6px 15px rgba(0, 0, 0, 0.7);
    text-align: center;
}

/* Heading Styling */
h1 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    color: #58a6ff; 
}

/* Input Styling */
input[type="text"] {
    width: 85%;
    padding: 12px;
    margin-bottom: 20px;
    border: none;
    border-radius: 8px;
    background-color: #21262d; 
    color: #c9d1d9; 
    font-size: 1rem;
}

input[type="text"]::placeholder {
    color: #8b949e; 
}

/* Button Styling */
button {
    padding: 12px 25px;
    margin: 10px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

#addt {
    background-color: #238636;
    color: #ffffff;
}

#addt:hover {
    background-color: #2ea043;
    transform: scale(1.05);
}

#remt {
    background-color: #d73a49;
    color: #ffffff;
}

#remt:hover {
    background-color: #cb2431;
    transform: scale(1.05);
}

/* Task Holder Styling */
#holder {
    margin-top: 20px;
    padding: 15px;
    border-radius: 10px;
    background-color: #21262d; 
    max-height: 300px;
    overflow-y: auto;
    box-shadow: inset 0px 4px 8px rgba(0, 0, 0, 0.6);
}

/* Task Styling */
.task {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px;
    margin: 8px 0;
    border-radius: 8px;
    background-color: #30363d; 
    color: #c9d1d9;
    font-size: 1rem;
    transition: transform 0.2s ease, background-color 0.3s ease, opacity 0.3s ease;
}

.task:hover {
    background-color: #394049;
    transform: scale(1.02);
}

/* Highlight Incomplete Tasks */
.task:not(.completed) {
    background-color: #394049; 
    border-left: 4px solid #58a6ff;
}

/* Dull Completed Tasks */
.task.completed {
    background-color: #21262d; 
    color: #8b949e; 
    opacity: 0.6;
    text-decoration: line-through;
}

/* Checkbox Styling */
.task input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

/* Scrollbar Styling */
#holder::-webkit-scrollbar {
    width: 8px;
}

#holder::-webkit-scrollbar-thumb {
    background-color: #444c56;
    border-radius: 5px;
}

#holder::-webkit-scrollbar-thumb:hover {
    background-color: #586069;
}

#holder::-webkit-scrollbar-track {
    background-color: #21262d;
}


@media (max-width: 600px) {
    .container {
        width: 95%;
        padding: 20px;
    }

    h1 {
        font-size: 2rem;
    }

    input[type="text"] {
        width: 100%;
    }

    button {
        width: 100%;
        margin: 8px 0;
    }
}