/* ============================= */
/*  Theme Variables Setup      */
/* ============================= */

/* Default Dark Theme Variables */
:root {
    --bg-color: #1e1e1e;
    /* Background color of calculator */
    --text-color: #0f0;
    /* Text color for display and buttons */
    --btn-color: #2d2d2d;
    /* Default button background */
    --btn-hover: #00adb5;
    /* Hover color on buttons */
    --operator-color: #393e46;
    /* Background color for operator buttons */
    --memory-color: #6c5ce7;
    /* Background color for memory buttons */
    --equal-color: #00adb5;
    /* Background for equal button */
    --clear-color: #ff5722;
    /* Background for clear button */
}

/* Light Theme Override Variables */
body.light {
    --bg-color: #f1f1f1;
    /* Light background for calculator */
    --text-color: #222;
    /* Darker text for light theme */
    --btn-color: #fefefe;
    /* Light background for buttons */
    --btn-hover: #007bff;
    /* Blue hover color */
    --operator-color: #d3d3d3;
    /* Light operator background */
    --memory-color: #6f42c1;
    /* Purple for memory button */
    --equal-color: #007bff;
    /* Blue for equal button */
    --clear-color: #dc3545;
    /* Red for clear button */
    background: linear-gradient(to right, #ffffff, #e6e6e6);
    /* Light gradient */
}

/* ============================= */
/*  Reset and Base Styles      */
/* ============================= */

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

/* Base layout for calculator on page */
body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    font-family: 'Orbitron', sans-serif;
    padding: 20px;
    transition: background 0.4s ease;
}

/* ============================= */
/*  Calculator Container Style */
/* ============================= */

.calculator {
    background: var(--bg-color);
    /* Dynamic background */
    border-radius: 20px;
    /* Rounded corners */
    padding: 20px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 30px 50px rgba(0, 0, 0, 0.5);
    /* Depth shadow */
    transition: all 0.4s ease;
    transform: perspective(1000px) rotateX(4deg);
    /* 3D tilt effect */
    animation: popUp 0.8s ease-out;
    /* Entry animation */
    position: relative;
    backdrop-filter: blur(12px);
    /* Glass effect */
    border: 1px solid rgba(255, 255, 255, 0.1);
    /* Soft border */
}

/* ============================= */
/*  Animation for Pop-Up       */
/* ============================= */

@keyframes popUp {
    0% {
        opacity: 0;
        transform: scale(0.8) rotateX(10deg);
    }

    100% {
        opacity: 1;
        transform: scale(1) rotateX(0deg);
    }
}

/* ============================= */
/*  Theme Switch Toggle        */
/* ============================= */

.form-check.form-switch {
    position: absolute;
    top: -50px;
    right: 0;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Toggle switch border black */
.form-check-input {
    border: 2px solid black;
    /*  this sets black border */
}


/* ============================= */
/*  Display Bar Style          */
/* ============================= */

.display {
    background: rgba(0, 0, 0, 0.6);
    border-radius: 12px;
    color: var(--text-color);
    /* Dynamic text color */
    padding: 20px;
    font-size: 2rem;
    text-align: right;
    overflow-x: auto;
    /* Scrollable display */
    white-space: nowrap;
    text-shadow: 0 0 8px limegreen;
    /* Glowing text */
    box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.4);
    /* Inset shadow */
    border: 1px solid rgba(255, 255, 255, 0.1);
}

/* ============================= */
/*  Button Grid Layout         */
/* ============================= */

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    /* 4 columns */
    gap: 15px;
    margin-top: 20px;
}

/* ============================= */
/*  Button Common Styles       */
/* ============================= */

button {
    padding: 20px;
    border: none;
    border-radius: 14px;
    background: var(--btn-color);
    /* Dynamic background */
    color: var(--text-color);
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.2s ease;
    transform: translateZ(0);
    box-shadow:
        4px 4px 10px rgba(0, 0, 0, 0.4),
        -4px -4px 10px rgba(255, 255, 255, 0.1),
        inset -2px -2px 5px rgba(255, 255, 255, 0.05),
        inset 2px 2px 5px rgba(0, 0, 0, 0.2);
}

/* On Hover - scale and color change */
button:hover {
    background: var(--btn-hover);
    transform: scale(1.05);
}

/* On Active - press down effect */
button:active {
    box-shadow:
        inset 4px 4px 8px rgba(0, 0, 0, 0.5),
        inset -4px -4px 8px rgba(255, 255, 255, 0.05);
    transform: scale(0.96);
}

/* ============================= */
/*  Special Button Styles       */
/* ============================= */

/* Equal Button */
.equal {
    background: var(--equal-color);
    color: white;
    box-shadow:
        0 0 15px var(--equal-color),
        inset -2px -2px 4px rgba(255, 255, 255, 0.2),
        inset 2px 2px 4px rgba(0, 0, 0, 0.4);
}

/* Clear Button */
.clear {
    background: var(--clear-color);
    color: white;
    box-shadow:
        0 0 15px var(--clear-color),
        inset -2px -2px 4px rgba(255, 255, 255, 0.2),
        inset 2px 2px 4px rgba(0, 0, 0, 0.4);
}

/* Operator Buttons (+, -, *, /) */
.operator {
    background: var(--operator-color);
    box-shadow:
        3px 3px 8px rgba(0, 0, 0, 0.4),
        inset -2px -2px 5px rgba(255, 255, 255, 0.08),
        inset 2px 2px 5px rgba(0, 0, 0, 0.3);
}

/* Memory Buttons (M+, MR, etc.) */
.memory {
    background: var(--memory-color);
    color: white;
    box-shadow:
        0 0 12px var(--memory-color),
        inset -1px -1px 3px rgba(255, 255, 255, 0.2),
        inset 1px 1px 3px rgba(0, 0, 0, 0.4);
}

/* ============================= */
/*  Responsive Support         */
/* ============================= */

@media (max-width: 480px) {
    button {
        padding: 16px;
        font-size: 1rem;
    }

    .display {
        font-size: 1.5rem;
    }
}