:root {
    --background-color: #f0efef;
    --operator-color: #ffa000;
    --clear-color: #e44338;
    --equals-color: #407eeb;
}

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

body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: var(--background-color);
}

.calculator {
    width: 100%;
    max-width: 20rem;
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
    margin: 0 1rem;
}

.historic {
    color: #777;
    width: 100%;
    padding: .6rem 1rem;
    font-size: 1em;
    text-align: right;
    border-top: 10px solid #fff;
    border-left: 10px solid #fff;
    border-right: 10px solid #fff;
    border-bottom: none;
    border-radius: 10px 10px 0 0;
    background-color: color-mix(in srgb, #fff, #000 10%);
}

.display {
    color: black;
    width: 100%;
    padding: 1rem;
    font-size: 2em;
    text-align: right;
    border-top: none;
    border-left: 10px solid #fff;
    border-right: 10px solid #fff;
    border-bottom: 10px solid #fff;
    border-radius: 10px 10px 0 0;
    background-color: color-mix(in srgb, #fff, #000 10%);
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: .6rem;
    grid-template-rows: repeat(5, auto);
    padding: .6rem;
}

button {
    padding: 1rem;
    font-size: 1.5em;
    cursor: pointer;
    border: none;
    background-color: var(--background-color);
    border-radius: 5px;
    transition: background-color 0.3s;
}

button:hover {
    background-color: color-mix(in srgb, var(--background-color), #000 13%);
}

button.operator {
    background-color: var(--operator-color);
    color: #fff;
}

button.operator:hover {
    background-color: color-mix(in srgb, var(--operator-color), #000 13%);
}

button.clear {
    background-color: var(--clear-color);
    color: #fff;
}

button.clear:hover {
    background-color: color-mix(in srgb, var(--clear-color), #000 13%);
}

button.equals {
    background-color: var(--equals-color);
    color: #fff;
    grid-row: span 2;
}

button.equals:hover {
    background-color: color-mix(in srgb, var(--equals-color), #000 13%);
}

/* Dark mode */
/* Dark Mode Button Styles */
.dark-mode-btn {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 10px 20px;
    background-color: var(--operator-color);
    color: white;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    z-index: 1000;
}

.dark-mode-btn:hover {
    background-color: color-mix(in srgb, var(--operator-color), #000 15%);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.dark-mode-btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

/* Dark Mode Styles */
body.dark-mode {
    background-color: #1a1a1a;
    color: #ffffff;
}

body.dark-mode .calculator {
    background-color: #2d2d2d;
    box-shadow: 0 0 15px rgba(255, 255, 255, 0.1);
}

body.dark-mode .historic {
    background-color: #3d3d3d;
    color: #cccccc;
    border-color: #2d2d2d;
}

body.dark-mode .display {
    background-color: #3d3d3d;
    color: #ffffff;
    border-color: #2d2d2d;
}

body.dark-mode button:not(.operator):not(.clear):not(.equals) {
    background-color: #4d4d4d;
    color: #ffffff;
}

body.dark-mode button:not(.operator):not(.clear):not(.equals):hover {
    background-color: color-mix(in srgb, #4d4d4d, #fff 15%);
}

body.dark-mode .operator {
    background-color: var(--operator-color);
}

body.dark-mode .operator:hover {
    background-color: color-mix(in srgb, var(--operator-color), #fff 15%);
}

body.dark-mode .clear {
    background-color: var(--clear-color);
}

body.dark-mode .clear:hover {
    background-color: color-mix(in srgb, var(--clear-color), #fff 15%);
}

body.dark-mode .equals {
    background-color: var(--equals-color);
}

body.dark-mode .equals:hover {
    background-color: color-mix(in srgb, var(--equals-color), #fff 15%);
}

body.dark-mode .dark-mode-btn {
    background-color: var(--operator-color);
    color: #1a1a1a;
    box-shadow: 0 2px 8px rgba(255, 255, 255, 0.1);
}

body.dark-mode .dark-mode-btn:hover {
    background-color: color-mix(in srgb, var(--operator-color), #1a1a1a 15%);
    color: #ffffff;
}