/* 
  Main Project Styles
  Simple, clean, and modern calculator design.
*/

/* --- Variables --- */
:root {
    /* Colors */
    --bg-main: #121212;
    --bg-card: rgba(30, 30, 35, 0.8);
    --bg-display: #1a1a1a;

    --text-main: #ffffff;
    --text-muted: #a0a0a0;
    --text-black: #000000;

    /* Button Colors */
    --btn-num-bg: #2d2d2d;
    --btn-num-hover: #3d3d3d;

    --btn-op-bg: #ff9f0a;
    --btn-op-hover: #ffb03a;

    --btn-clear-bg: #ff453a;
    --btn-clear-hover: #ff6961;

    /* Layout & Effects */
    --radius-l: 24px;
    --radius-m: 16px;
    --shadow-heavy: 0 20px 50px rgba(0, 0, 0, 0.5);
    --shadow-light: 0 4px 6px rgba(0, 0, 0, 0.2);
}

/* --- Global Setup --- */
body {
    background-color: var(--bg-main);
    background-image: radial-gradient(circle at 50% 0%, #2a2a35 0%, #121212 100%);
    color: var(--text-main);
    font-family: -apple-system, sans-serif;
    margin: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

/* --- App Container --- */
.app-container {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fade-in 0.8s ease-out;
}

/* --- Calculator Wrapper (The Card) --- */
.calculator-wrap {
    background-color: var(--bg-card);
    backdrop-filter: blur(20px);
    width: 360px;
    padding: 24px;
    border-radius: var(--radius-l);
    box-shadow: var(--shadow-heavy);
    border: 1px solid rgba(255, 255, 255, 0.1);
    display: flex;
    flex-direction: column;
    gap: 20px;
}

/* --- Display Area --- */
.display-area {
    background-color: var(--bg-display);
    border-radius: var(--radius-m);
    padding: 24px;
    text-align: right;
    margin-bottom: 10px;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    overflow: hidden;
    /* Hide if numbers get too long */
}

.display-text {
    font-size: 3rem;
    font-weight: 300;
    white-space: nowrap;
    background: linear-gradient(180deg, #fff 0%, #e0e0e0 100%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    /* Fallback */
}

.operator-symbol {
    color: var(--btn-op-bg);
    /* Use operator color for visibility */
    font-weight: 500;
    margin: 0 4px;
    /* Reset gradient text effect for symbol to make it solid color */
    -webkit-text-fill-color: var(--btn-op-bg);
}

/* --- Keypad Grid --- */
.keypad-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}

/* --- Buttons --- */
.calc-btn {
    border: none;
    outline: none;
    font-size: 1.5rem;
    font-weight: 500;
    padding: 20px 0;
    border-radius: var(--radius-m);
    cursor: pointer;
    transition: transform 0.1s, filter 0.2s;
    box-shadow: var(--shadow-light);
    color: var(--text-main);
    position: relative;
    /* For overflow/effects */
    overflow: hidden;
}

/* Button Interactions */
.calc-btn:active {
    transform: scale(0.95);
}

.calc-btn:hover {
    filter: brightness(1.1);
}

/* Button Variants */
.btn-number {
    background-color: var(--btn-num-bg);
}

.btn-operator {
    background-color: var(--btn-op-bg);
    color: var(--text-black);
    font-weight: 600;
}

.btn-equals {
    grid-column: span 4;
    /* Full width */
    background-color: var(--btn-op-bg);
    color: var(--text-black);
    margin-top: 12px;
}

.btn-clear {
    background-color: var(--btn-clear-bg);
    color: white;
}

.btn-zero {
    grid-column: span 2;
    /* Double width */
    text-align: left;
    padding-left: 32px;
}

/* --- Animations --- */
@keyframes fade-in {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* --- Responsiveness --- */
@media (max-height: 700px) {
    .calculator-wrap {
        padding: 16px;
        gap: 12px;
    }

    .calc-btn {
        padding: 16px 0;
        font-size: 1.25rem;
    }
}