main.css

:root{
    --clr-primary: rgb(54, 112, 119);
    --clr-light: #f4f4f4;
    --clr-dark: #333;
    --clr-warning: rgb(99, 36, 36);
}
*,
*::before,
*::after {
    font-family: inherit;
    box-sizing: border-box;
}
body{
    margin: 0;
    font-family: "Work Sans", sans-serif;
    font-weight: 300;
    font-size: 1.5rem;
    background-color: var(--clr-primary);
    color: var(--clr-light);

    display: grid;
    grid:
"header header header header" auto
"...... lists active ......" auto /
1fr minmax(100px, 300px) minmax(250px, 500px)
}
.title{
    padding-top: 10px;
    grid-area: header;
    text-align: center;
    font-size: calc(4vw + 1rem);
    font-weight: 700;
    color: #000; 
    margin: -0.3em 0 0.5em; 
}
.task-lists{
    line-height: 1.7;
    font-size: 1.2rem;
    list-style: circle;
    font-weight: 900;
    padding-left: 1.1em;
}
.list-name{
    cursor: pointer;
}
.list-name:hover{
    opacity: 0.7;
}

form{
    display: flex;
}
.btn{
    cursor: pointer;
    background: 0;
    border: 0;     
    padding: 0;
    color: inherit;
    font-size: 1rem;
}
.btn.create{
    font-size: 1.5rem;
    font-weight: 900 ;
    margin-right: 0.25em;
    transition: opacity 250ms ease-in-out ;
}
.btn.create:hover{
    opacity: 0.7;
}
.btn.delete{
    opacity: 0.7;
    font-size: 1rem;
    transition: color 200ms;
}
.btn.delete:hover{
    color: var(--clr-warning);
}
.all-tasks{
    grid-area: lists;
}

.todo-list{
    --spacer: 2rem;
    
    grid-area: active;
    background: var(--clr-light);
    color: var(--clr-dark);
}
.todo-header{
    padding: var(--spacer);  
    background: #e4e4e4;
    display: flex;
    align-content: center;
    justify-content: space-between;
}
.list-title{
    margin: 0;
    margin-right: 0 1em 0 0;
}
.task-count{
    margin: 0;
    font-size: 1rem
}
.todo-body{
    padding: var(--spacer);
    position: relative;
}
.new-task-creator .create{
    color: var(--clr-primary);

}
.new{
    background: transparent;
    border: 0;
    color: inherit;
    border-bottom: 1px solid currentColor;
    padding: 0.25em;
    font-size: inherit;
    outline: none;
    transition: border-bottom 150ms ease-in;
    order: 2;
}
.new::placeholder{
    opacity: 0.4;
}
.new:focus{
    border-bottom-width: 3px;
}
.new:focus::placeholder{
    opacity: 0.15;
}
.new.list{
    font-size: 1.1rem;
}
.new.task{
    margin-bottom: 0 ;
}
.active-lists{
    font-weight: 900;
}
[type= "checkbox"]{
    opacity: 0;
    position: absolute;
}
.task label{
    display: inline-flex;
    align-items: center;
    position: relative;
}
.task{
    position: relative;
    margin-bottom: 1.25em;
    
}
.task::after{
    position: absolute;
    content: "";
    right: 0;
    left: 0;
    bottom: -0.5em;
    height: 1px;
    background: currentColor;
    opacity: 0.1;


}
.custom-checkbox{
    size: 0.75em;
    display: inline-block;
    width: var(--size);
    height: var(--size);
    margin-right: var(--size);
    cursor: pointer;
    border: 2px solid currentColor;
    border-radius: 50%;
    transform: scale(1);
    transition: transform 300ms ease-in-out;
}
.task:hover .custom-checkbox,
 [type="checkbox"]:focus + label .custom-checkbox{
    transform: scale(1.2);
    color: var(--clr-primary);
}
[type="checkbox"]:checked + label .custom-checkbox{
    background: var(--clr-primary);
    border-color: var(--clr-primary);
    box-shadow: inset 0 0 0px 2px white; 

} 
[type= "checkbox"]:checked + label{
    opacity: 0.5;
}
.task label::after{
    content: "";
    position: absolute;
    left: 1.5em;
    right: 0;
    top: 50%;
    height: 3px;
    background: currentColor;
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 150ms ease-in-out;
}
[type= "checkbox"]:checked + label::after{
   transform: scaleX(1);
   transform-origin: left;
}
.delete-things{
    display: flex;
    justify-content: space-evenly;
    position: absolute;
    width: 100%;
    left: 0;
    bottom: -35px;
    color: var(--clr-light);
}