body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: var(--bg-color);
    margin: 0;
    position: relative;
}

.calculator {
    background-color: var(--calc-bg);
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
    width: 300px;
    position: relative;
}

input[type="text"] {
    width: 100%;
    height: 60px;
    text-align: right;
    margin-bottom: 10px;
    font-size: 32px;
    border: none;
    border-radius: 8px;
    background-color: var(--input-bg);
    color: var(--input-color);
    padding: 10px 20px;
    box-sizing: border-box;
}

#answer-preview {
    text-align: right;
    font-size: 18px;
    color: var(--preview-color);
    margin-bottom: 10px;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

button {
    height: 60px;
    font-size: 24px;
    border: none;
    border-radius: 8px;
    background-color: var(--button-bg);
    color: var(--button-color);
    cursor: pointer;
    transition: background-color 0.3s, transform 0.3s;
}

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

button:active {
    background-color: var(--button-active);
    color: var(--button-active-text);
    transform: scale(0.98);
}

#settings-button {
    position: absolute;
    bottom: 20px;
    left: 20px;
    background-color: var(--button-bg);
    color: var(--button-color);
    border: none;
    border-radius: 50%;
    padding: 10px;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.3s;
    font-size: 24px;
    width: 50px;
    height: 50px;
}

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

.settings-menu {
    background-color: var(--calc-bg);
    border-radius: 8px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    padding: 20px;
    position: fixed;
    bottom: 80px;
    left: 20px;
    width: 200px;
}

#settings label, #settings p {
    color: var(--text-color);
}

.history {
    position: fixed;
    left: 20px;
    top: 20px;
    background-color: var(--calc-bg);
    color: var(--input-color);
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
    width: 200px;
    max-height: 80vh;
    overflow-y: auto;
}

.history h3 {
    margin-top: 0;
}

.hidden {
    display: none;
}

.switch-container {
    position: absolute;
    top: 20px;
    right: 20px;
}

.switch {
    position: relative;
    display: inline-block;
    width: 60px;
    height: 34px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 26px;
    width: 26px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: #61dafb;
}

input:checked + .slider:before {
    transform: translateX(26px);
}

/* Notification styles */
.notification {
    background-color: var(--calc-bg);
    color: var(--text-color);
    padding: 10px;
    border-radius: 8px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    position: fixed;
    top: 10px;
    right: 10px;
    width: 250px;
    z-index: 1000;
    transition: opacity 0.3s, transform 0.3s;
    cursor: grab;
}

.notification.hidden {
    opacity: 0;
    pointer-events: none;
}

.notification.visible {
    opacity: 1;
    pointer-events: auto;
}

.notification.swiped {
    transform: translateX(100%);
    opacity: 0;
}

/* Dark Mode */
:root {
    --bg-color: #282c34;
    --calc-bg: #20232a;
    --input-bg: #3a3f47;
    --input-color: #61dafb;
    --preview-color: lightgray;
    --button-bg: #3a3f47;
    --button-color: #61dafb;
    --button-hover: #282c34;
    --button-active: #61dafb;
    --button-active-text: #20232a;
    --text-color: lightgray;
}

/* Light Mode */
.light-mode {
    --bg-color: #f0f0f0;
    --calc-bg: #fff;
    --input-bg: #eee;
    --input-color: #000;
    --preview-color: gray;
    --button-bg: #ddd;
    --button-color: #000;
    --button-hover: #ccc;
    --button-active: #bbb;
    --button-active-text: #000;
    --text-color: #000;
}

/* Responsive Design */
@media (max-width: 600px) {
    .calculator {
        width: 90%;
        padding: 10px;
    }

    input[type="text"] {
        height: 50px;
        font-size: 24px;
    }

    .buttons button {
        height: 50px;
        font-size: 20px;
    }

    #settings-button {
        width: 40px;
        height: 40px;
        font-size: 20px;
    }

    .settings-menu {
        width: 90%;
    }
}