:root {
    --main-bg: hsl(222, 26%, 31%);
    --toggle-bg: hsl(223, 31%, 20%);
    --scrn-bg: hsl(224, 36%, 15%);
    --acc-key-bg: hsl(6, 63%, 50%);
    --acc-key-sd: hsl(6, 70%, 34%);
    --main-key-bg: hsl(30, 25%, 89%);
    --main-key-sd: hsl(28, 16%, 65%);
    --sec-key-bg: hsl(225, 21%, 49%);
    --sec-key-sd: hsl(224, 28%, 35%);
    --text-color: hsl(221, 14%, 31%);
    --color-text-head: hsl(0, 0%, 100%);
    --color-sec: hsl(0, 0%, 100%);
    --color-equal: hsl(0, 0%, 100%);
}

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

body {
    font-family: "League Spartan", sans-serif;
    background-color: var(--main-bg);
}

.container {
    width: min(400px, 90vw);
    margin-inline: auto;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.header {
    padding: 18px 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header h1 {
    color: var(--color-text-head);
}

.toggle {
    display: flex;
    align-items: center;
}

.toggle span {
    font-size: 11px;
    font-weight: 700;
    color: var(--color-text-head);
    margin-right: 10px;
}

.theme-toggle input[type="radio"] {
    display: none;
}

.slider {
    display: flex;
    position: relative;
    width: 70px;
    background-color: var(--toggle-bg);
    border-radius: 30px;
    /* overflow: hidden; */
    padding: 5px;
}

.slider .option {
    width: 20px;
    height: 20px;
    flex: 1;
    text-align: center;
    font-size: 14px;
    cursor: pointer;
    z-index: 2;
}

.slider-button {
    position: absolute;
    width: 20px;
    height: 20px;
    background-color: var(--acc-key-bg);
    border-radius: 15px;
    transition: transform 0.3s;
    z-index: 1;
}

#dark:checked ~ .slider .slider-button {
    transform: translateX(0);
}

#light:checked ~ .slider .slider-button {
    transform: translateX(20px);
}

#neon:checked ~ .slider .slider-button {
    transform: translateX(40px);
}

input[type="radio"]:checked + .slider .option {
    color: #fff;
}

.option::before {
    content: '';
    position: absolute;
    top: -18px;
    font-weight: 700;
    color: var(--color-text-head);
}

.option:nth-child(1)::before {
    content: '1';
    left: 10%;
}

.option:nth-child(2)::before {
    content: '2';
    left: 45%;
}

.option:nth-child(3)::before {
    content: '3';
    right: 10%;
}


.screen {
    margin-bottom: 16px;
    padding: 0 10px;
    height: 80px;
    background: var(--scrn-bg);
    text-align: right;
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: end;
    overflow: hidden;
}

.screen span {
    display: inline-block;
    font-weight: 700;
    color: var(--color-text-head);
}

.display-operation {
    font-size: 32px;
}

.display-result {
    font-size: 16px;
    opacity: .5;
}

.buttons {
    padding: 16px;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    background: var(--toggle-bg);
    border-radius: 8px;
}

.btn {
    padding: 10px;
    font-weight: 700;
    font-size: 24px;
    border: none;
    border-radius: 8px;
    border-bottom: 3px solid var(--main-key-sd);
    background: var(--main-key-bg);
    color: var(--text-color);
    cursor: pointer;
}

.btn:active {
    border-bottom: 2px solid var(--main-key-bg);
}

.btn-span-2 {
    grid-column: span 2;
}

#delete, #clear-all {
    background: var(--sec-key-bg);
    border-color: var(--sec-key-sd);
    color: var(--color-sec);
    font-size: 18px;
}

#equal-to {
    background: var(--acc-key-bg);
    border-color: var(--acc-key-sd);
    color: var(--color-equal);
    font-size: 18px;
}

:root:has(#light:checked) {
    --main-bg: hsl(0, 0%, 90%);
    --toggle-bg: hsl(0, 5%, 81%);
    --scrn-bg: hsl(0, 0%, 93%);
    --acc-key-bg: hsl(25, 98%, 40%);
    --acc-key-sd: hsl(25, 99%, 27%);
    --main-key-bg: hsl(45, 7%, 89%);
    --main-key-sd: hsl(35, 11%, 61%);
    --sec-key-bg: hsl(185, 42%, 37%);
    --sec-key-sd: hsl(185, 58%, 25%);
    --text-color: hsl(60, 10%, 19%);
    --color-text-head: hsl(60, 10%, 19%);
    --color-sec: hsl(0, 0%, 100%);
    --color-equal: hsl(0, 0%, 100%);
}

:root:has(#neon:checked) {
    --main-bg: hsl(268, 75%, 9%);
    --toggle-bg: hsl(268, 71%, 12%);
    --scrn-bg: hsl(268, 71%, 12%);
    --acc-key-bg: hsl(176, 100%, 44%);
    --acc-key-sd: hsl(177, 92%, 70%);
    --main-key-bg: hsl(281, 89%, 26%);
    --main-key-sd: hsl(285, 91%, 52%);
    --sec-key-bg: hsl(268, 47%, 21%);
    --sec-key-sd: hsl(290, 70%, 36%);
    --text-color: hsl(52, 100%, 62%);
    --color-text-head: hsl(52, 100%, 62%);
    --color-sec: hsl(0, 0%, 100%);
    --color-equal:  hsl(198, 20%, 13%);
}