:root {
    --nokia-bg: #c6f196;
    --nokia-fg: #2c3527;
    --nokia-dim: #accf84;
    --phone-body: #3d5a80; /* Classic dark blue/greyish */
    --phone-housing: #98c1d9;
    --key-color: #e0e0e0;
    --key-text: #333;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    touch-action: manipulation; /* Allow clicks but prevent double-tap zoom */
}

body {
    background-color: #293241;
    font-family: 'VT323', monospace;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: var(--nokia-fg);
    overflow: hidden; /* Prevent scrolling on mobile */
}

.game-container {
    display: flex;
    flex-direction: column;
    align-items: center;
}

/* Phone Body */
.nokia-phone-body {
    background-color: var(--phone-body);
    border-radius: 40px 40px 60px 60px; /* Nokia shape approx */
    padding: 40px 20px 60px 20px;
    box-shadow: 
        inset 5px 5px 15px rgba(255,255,255,0.2),
        inset -5px -5px 15px rgba(0,0,0,0.4),
        10px 10px 30px rgba(0,0,0,0.5);
    border: 8px solid #333;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    width: 360px;
    /* Scale down for small screens if needed */
    transform-origin: center;
}

/* Screen adjustments */
.nokia-screen {
    background-color: var(--nokia-bg);
    border: 4px solid #555;
    border-radius: 10px;
    padding: 10px;
    width: 250px; /* Fixed width for the phone screen look */
    height: 200px; /* Fixed height */
    box-shadow: inset 0 0 10px rgba(0,0,0,0.1);
    position: relative;
    display: flex;
    flex-direction: column;
}

.header {
    display: flex;
    justify-content: space-between;
    font-size: 1.2rem;
    border-bottom: 2px solid var(--nokia-fg);
    margin-bottom: 2px;
    padding-bottom: 2px;
}

.canvas-wrapper {
    position: relative;
    border: 2px solid var(--nokia-dim);
    flex-grow: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--nokia-bg);
    overflow: hidden; /* Fixes overlay spilling out */
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
    image-rendering: pixelated;
}

.branding {
    font-family: sans-serif;
    font-weight: bold;
    color: #ccc;
    font-size: 1.2rem;
    letter-spacing: 2px;
}

/* Keypad */
.keypad {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.nav-keys {
    display: flex;
    justify-content: space-between;
    width: 100%;
    padding: 0 10px;
}

.nav-btn {
    background: #fff;
    border: none;
    border-radius: 10px;
    height: 30px;
    width: 50px;
    box-shadow: 0 4px 0 #999;
}

.nav-btn.large {
    height: 40px;
    width: 80px;
    background: #e0e0e0;
    border-radius: 15px;
    margin-top: -10px; /* Center giant button style */
}

.num-keys {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

.num-btn {
    width: 70px;
    height: 45px;
    background: linear-gradient(145deg, #ffffff, #e6e6e6);
    border: 1px solid #ccc;
    border-radius: 15px 15px 25px 25px; /* Pill shape */
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    font-family: sans-serif;
    font-weight: bold;
    color: var(--nokia-fg);
    font-size: 1.2rem;
    box-shadow: 0 3px 0 #999, 1px 1px 2px rgba(0,0,0,0.2);
    cursor: pointer;
    user-select: none;
    transition: transform 0.1s, box-shadow 0.1s;
}

.num-btn:active {
    transform: translateY(3px);
    box-shadow: 0 0 0 #999;
    background: #ddd;
}

/* Overlay */
.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(198, 241, 150, 0.95);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 10;
}

.overlay.hidden {
    display: none;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

p {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
}

.retro-btn {
    background: transparent;
    border: 2px solid var(--nokia-fg);
    color: var(--nokia-fg);
    font-family: 'VT323', monospace;
    font-size: 1.2rem;
    padding: 5px 15px;
    cursor: pointer;
    text-transform: uppercase;
}

.controls-hint {
    margin-top: 20px;
    color: #888;
    text-align: center;
}

.Desktop-only {
    display: block;
}

/* Logic Highlights for 2, 4, 6, 8 */
.num-btn[data-key="2"],
.num-btn[data-key="4"],
.num-btn[data-key="6"],
.num-btn[data-key="8"] {
    position: relative;
}

/* Mobile Responsiveness */
@media (max-width: 600px) {
    body {
        /* On mobile, we might want to scale slightly if screen is tiny */
        height: 100vh;
        width: 100vw;
    }
    
    .nokia-phone-body {
        transform: scale(0.9); /* Scale down slightly to fit standard phones if needed */
        margin: 0;
    }
    
    .controls-hint.Desktop-only {
        display: none;
    }
}