@font-face {
	font-family: IRANSansX;
	font-style: normal;
	font-weight: normal;
	src: url('fonts/IRANSansXFaNum-Regular.woff') format('woff'),   
	url('fonts/IRANSansXFaNum-Regular.woff2') format('woff2');	
}
:root {
    --bg-color: #f4f4f4;
    --calc-bg: #f9f9f9;
    --display-bg: #f5f5f5;
    --btn-bg-light: #f0f0f0;
    --btn-bg-dark: #e0e0e0;
    --btn-bg-op: #4b4b4b; /* Operator buttons */
    --btn-bg-eq: #ff8c00; /* Equals button */
    --text-main: #333;
    --text-op: #fff;
    --border-radius: 8px;
    --border-color: #eaeaea;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: var(--bg-color);
}
h1{
    text-align: center;
    background-color: #282a36;
    color: #ff9800;
    padding: 10px 0;
    margin: 0;
    font-family:IRANSansX;
}
/* Main calculator container */
.calculator {
    background-color: var(--calc-bg);
    border-radius: var(--border-radius);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    width: 380px;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

/* Display area */
.display {
    background-color: var(--display-bg);
    padding: 20px;
    text-align: right;
    border-bottom: 1px solid var(--border-color);
    min-height: 90px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
}

.display .expression {
    font-size: 1rem;
    color: #888;
    min-height: 1.2rem;
    margin-bottom: 5px;
}

.display .result {
    font-size: 2.5rem;
    color: var(--text-main);
    word-wrap: break-word;
    word-break: break-all;
}

/* Button grid layout */
.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1px;
    background-color: var(--border-color); /* Acts as border between buttons */
}

/* General button styling */
button {
    border: none;
    outline: none;
    background-color: white;
    color: var(--text-main);
    font-size: 1.1rem;
    padding: 20px 10px;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.25, 0.46, 0.45, 0.94); /* Smooth animation */
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Button Hover & Active Animations */
button:hover {
    background-color: var(--btn-bg-light);
}

button:active {
    transform: scale(0.95); /* Press effect */
    background-color: var(--btn-bg-dark);
}

/* Specific button groups */
.btn-sci {
    background-color: #fafafa;
    font-size: 1rem;
}

.btn-num {
    background-color: #e6e6e6;
    font-size: 1.4rem;
    font-weight: 500;
}

.btn-op {
    background-color: var(--btn-bg-op);
    color: var(--text-op);
    font-size: 1.4rem;
}

.btn-op:hover {
    background-color: #3a3a3a;
}

.btn-eq {
    background-color: var(--btn-bg-eq);
    color: white;
    grid-column: span 2; /* Spans two columns */
    font-size: 1.5rem;
}

.btn-eq:hover {
    background-color: #e67e00;
}