* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

.container {
    min-height: 100vh;
    width: 100%;
    background: linear-gradient(135deg, #153677, #4e085f);
    padding: 20px;
}

.todo-app {
    max-width: 540px;
    background: #fff;
    margin: 100px auto;
    padding: 40px 30px;
    border-radius: 12px;
}

.todo-app h2 {
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: #003765;
    margin-bottom: 20px;
}

.todo-icon {
    width: 35px;
    height: 35px;
}

/* input row */
.row {
    display: flex;
    background: #edeef0;
    border-radius: 30px;
    padding-left: 20px;
    margin-bottom: 25px;
}

input {
    flex: 1;
    border: none;
    outline: none;
    background: transparent;
    padding: 12px;
    font-size: 14px;
}

button {
    border: none;
    outline: none;
    padding: 14px 40px;
    background: #ff5945;
    color: #fff;
    border-radius: 30px;
    cursor: pointer;
}

/* task list */
ul li {
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 10px;
    font-size: 16px;
}

/* left side: checkbox + text */
.task-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

ul li input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

ul li.checked span {
    text-decoration: line-through;
    color: #555;
}

ul li span {
    font-size: 16px;
}

/* delete button */
ul li button {
    background: crimson;
    color: #fff;
    border: none;
    padding: 6px 12px;
    font-size: 12px;
    border-radius: 10px;
    cursor: pointer;
}

/* mobile */
/* 🔥 MOBILE RESPONSIVENESS */
@media (max-width: 600px) {

    .todo-app {
        margin: 60px 15px;
        padding: 25px 20px 40px;
    }

    .todo-app h2 {
        font-size: 22px;
    }

    .row {
        flex-direction: column;
        gap: 12px;
        padding: 12px;
    }

    input {
        width: 100%;
        padding: 12px;
    }

    button {
        width: 100%;
        padding: 14px;
        border-radius: 30px;
    }

    ul li {
        font-size: 15px;
        padding: 10px;
    }

    ul li button {
        padding: 5px 10px;
        font-size: 11px;
    }

    .todo-icon {
        width: 30px;
        height: 30px;
    }
}