:root{
    --background-colour: #101114;
    --primary-colour: #1c1d20;
    --secondary-colour:#4a4d57;
    --accent-color: #00ca36;
    --text-color:#f9f9f9;
    --hover-color:#01e445;
}

html {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 1rem;
    color: var(--text-color);
}

body {
    min-height: 100vh;
    padding: 10px;
    background-color: var(--background-colour);
    display: flex;
    flex-direction: column;
    align-items: center;
}

h1 {
    margin-top: 100px;
    margin-bottom: 20px;
    font-size: 3rem;
    font-weight: 800;
    text-transform: uppercase;
    text-align: center;
    color: var(--accent-color);
}

.container {
    width: 700px;
    max-width: 100%;
    display: flex;
    flex-direction:column;
    gap: 10px;
}

#todo-input {
    box-sizing: border-box;
    padding: 12px 20px;
    width: 100%;
    background: none;
    border: 2px solid var(--secondary-colour);
    border-radius: 1000px;
    font: inherit; 
    color: var(--text-color);
    caret-color: var(--accent-color);
}

#todo-input:focus {
    outline: none;
}


form {
    position: relative;
}


#add-button {
    position: absolute;
    top: 0;
    right: 0;
    background-color: var(--accent-color);
    height: 100%;
    padding: 0px 30px;
    border: none;
    border-radius: 1000px;
    font: inherit;
    font-weight: 600;
    color: var(--background-colour);
    cursor: pointer;
}

#add-button:hover {
    background-color: var(--hover-color);
}

#add-button:active {
    background-color: var(--accent-color);
}

.todo{
    margin-bottom: 10px;
    padding: 0 16px;
    background-color: var(--primary-colour);
    border-radius: 15px;
    display: flex;
    align-items: center;
}

.todo .todo-text {
    padding: 15px;
    padding-right: 0;
    flex-grow: 1;
    transition: 250ms ease;
}

.delete-button {
    padding: 3px;
    background:none;
    border: none;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

.delete-button svg {
    transition: 250ms;
}

.delete-button:hover svg {
    fill: red;
}

.custom-checkbox {
    border: 2px solid var(--accent-color);
    border-radius: 50%;
    min-height: 20px;
    min-width: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 0;
    cursor: pointer;
    transition: 250ms ease;
}

input[type="checkbox"]:checked ~ .custom-checkbox {
 background-color: var(--accent-color);
}

input[type="checkbox"]:checked ~ .custom-checkbox svg {
    fill: var(--primary-colour);
}

input[type="checkbox"]:checked ~ .todo-text {
    text-decoration: line-through;
    color: var(--secondary-colour);
}

input[type="checkbox"] {
    display: none;
}

/*Responsive Design - mobile**/

@media(max-width:500px) {
html {
    font-size:1rem;
}
#add-button {
    position:unset;
    width:100%;
    height: auto;
    margin-top:100px;
    padding: 15px;
}

h1 {
    margin-top: 50px;
    font-size: 15vw;
}

} 
/*  only apply to device with lesser than 500px**/