/* General page and body styling (Dark Charcoal) */
body {
    background-color: #222;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    font-family: 'Inter', 'Arial', sans-serif; /* Modern font choice */
}


/* Calculator Frame (Near-Black with heavy rounded corners) */
.calculator-frame {
    width: 480px; /* Sightly narrower for a tighter feel */
    background-color: #111;
    padding: 30px;
    border-radius: 25px; /* Heavy roundness matching design */
    box-shadow: 0px 15px 35px rgba(0,0,0,0.4);
}

/* Updated Display Label (Solid rich orange, no border) */
#display-label {
    width: 100%;
    height: 75px;
    background-color: #FFA732; /* Warm orange */
    border: none; /* Remove old border */
    border-radius: 12px;
    box-sizing: border-box;
    font-size: 40px;
    color: black;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 15px;
    margin-bottom: 25px; /* Sightly more spacing */
    overflow-x: auto;
}

/* Updated Button Grid */
.buttons-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr); /* 4-column layout */
    gap: 15px; /* Clean, tight spacing */
}

/* Global button reset and base styling */
.btn {
    height: 70px; /* Updated height for better proportion */
    font-size: 28px;
    border: none; /* Removed old border */
    border-radius: 15px; /* High roundness matching design */
    cursor: pointer;
    font-weight: 500;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: transform 0.1s, opacity 0.1s;
    outline: none;
}

/* Button interactions */
.btn:active {
    transform: scale(0.95);
    opacity: 0.9;
}

/* Superscript styling */
sup {
    font-size: 60%;
    vertical-align: super;
}

/* --- Color and Component Mapping --- */

/* Number Buttons (Brown with white text) */
.num-btn {
    background-color: #4B2B1B;
    color: white;
}

/* Special Function Buttons (Olive with white text) */
.special-btn {
    background-color: #665E51;
    color: white;
}

/* Primary Operator Buttons Column (Terracotta orange) */
.op-btn {
    background-color: #FF9E4F;
    color: white;
}

/* Equal Button (Complex orange-yellow gradient with black text) */
.equal-btn {
    background-color: #FF9900; /* Fallback color */
    background-image: linear-gradient(135deg, #FF9900 0%, #FFC400 100%);
    color: black;
    font-weight: bold;
}

/* Clear Button (Near-Black with white text) */
.clear-btn {
    background-color: #111;
    color: white;
    font-size: 20px; /* Larger text for readability */
    font-weight: bold;
}