@import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@400;700;900&family=Rajdhani:wght@500;700&display=swap');

:root {
    --primary-rgb: 0, 240, 255;
    --bg-dark: #050508;
    --primary-color: #00f0ff;
    --secondary-color: #ff003c;
    --accent-color: #b026ff;
    --text-main: #ffffff;
    
    /* Glassmorphism Sudoku Cells */
    --cell-bg: rgba(20, 20, 35, 0.4);
    --cell-given: #ffffff;
    --cell-input: #00f0ff;
    --cell-error: #ff003c;
    --cell-selected: rgba(var(--primary-rgb), 0.5);
    --cell-highlight: rgba(var(--primary-rgb), 0.15);
    
    --grid-border: #00f0ff;
    --theme-glow: 0 0 15px rgba(var(--primary-rgb), 0.5);
    
    --level-hue: 180;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: 'Rajdhani', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    overflow: hidden;
    width: 100vw;
    height: 100vh;
    touch-action: none;
}

#bgCanvas, #fxCanvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
}

#fxCanvas {
    z-index: 100; /* Above UI for fireworks */
}

#game-container {
    position: relative;
    width: 100%;
    height: 100%;
    z-index: 10;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.screen {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.4s ease;
}

.screen.active {
    opacity: 1;
    visibility: visible;
}

.overlay {
    background: rgba(5, 5, 8, 0.85);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    z-index: 20;
}

.hidden {
    display: none !important;
}

/* Typography & Titles */
.logo h1 {
    font-family: 'Orbitron', sans-serif;
    font-size: 4rem;
    font-weight: 900;
    text-align: center;
    color: #fff;
    text-shadow: 0 0 10px var(--primary-color), 0 0 20px var(--primary-color), 0 0 40px var(--accent-color);
    margin-bottom: -10px;
}

.subtitle {
    font-family: 'Orbitron', sans-serif;
    font-size: 1.5rem;
    color: var(--secondary-color);
    text-align: center;
    letter-spacing: 5px;
    margin-bottom: 40px;
    text-shadow: 0 0 5px var(--secondary-color);
}

h2 {
    font-family: 'Orbitron', sans-serif;
    font-size: 2.5rem;
    margin-bottom: 20px;
    text-shadow: var(--theme-glow);
}

.win-title { color: #00ff66; text-shadow: 0 0 20px #00ff66; }
.lose-title { color: #ff003c; text-shadow: 0 0 20px #ff003c; }

/* Buttons */
button {
    font-family: 'Orbitron', sans-serif;
    font-weight: 700;
    cursor: pointer;
    border: none;
    outline: none;
    border-radius: 8px;
    transition: transform 0.1s, box-shadow 0.2s;
}

button:active {
    transform: scale(0.95);
}

.btn-3d {
    width: 280px;
    padding: 15px 20px;
    font-size: 1.2rem;
    margin: 10px 0;
    color: #fff;
    position: relative;
    background: linear-gradient(135deg, rgba(255,255,255,0.1), rgba(0,0,0,0.5));
    border: 2px solid;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.btn-3d.primary {
    border-color: var(--primary-color);
    box-shadow: 0 0 15px rgba(0, 240, 255, 0.4), inset 0 0 10px rgba(0, 240, 255, 0.2);
}
.btn-3d.primary:hover { box-shadow: 0 0 25px rgba(0, 240, 255, 0.8), inset 0 0 15px rgba(0, 240, 255, 0.5); }

.btn-3d.secondary {
    border-color: var(--accent-color);
    box-shadow: 0 0 15px rgba(176, 38, 255, 0.4), inset 0 0 10px rgba(176, 38, 255, 0.2);
}
.btn-3d.secondary:hover { box-shadow: 0 0 25px rgba(176, 38, 255, 0.8), inset 0 0 15px rgba(176, 38, 255, 0.5); }

.btn-3d.danger {
    border-color: var(--secondary-color);
    box-shadow: 0 0 15px rgba(255, 0, 60, 0.4), inset 0 0 10px rgba(255, 0, 60, 0.2);
}

.btn-3d.small { width: auto; font-size: 1rem; padding: 10px 15px; margin-top: 30px; border-color: #888; }

.btn-small {
    background: transparent;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
    padding: 8px 15px;
    font-size: 0.9rem;
}

/* Gameplay UI */
#gameplay {
    display: flex;
    flex-direction: column;
    justify-content: space-evenly;
    align-items: center;
    width: 100vw;
    height: 100vh;
    padding: 10px;
}

.hud {
    width: 100%;
    max-width: 450px;
    margin: 0 auto;
    flex-shrink: 0;
}

.hud-top {
    display: flex;
    justify-content: space-between;
    font-family: 'Orbitron', sans-serif;
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 5px;
    text-shadow: 0 0 5px var(--primary-color);
}

.hud-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: rgba(0,0,0,0.4);
    padding: 10px;
    border-radius: 8px;
    border: 1px solid rgba(0, 240, 255, 0.2);
}

.health-bar { display: flex; gap: 5px; }
.heart { color: var(--secondary-color); font-size: 1.2rem; text-shadow: 0 0 5px var(--secondary-color); }
.heart.empty { color: #555; text-shadow: none; }

.timer { 
    font-family: 'Orbitron', sans-serif; 
    font-size: 1.2rem; 
    color: #fff; 
}

.combo {
    font-family: 'Orbitron', sans-serif;
    color: #ffaa00;
    font-weight: 900;
    text-shadow: 0 0 10px #ffaa00;
    font-size: 1.2rem;
}
.combo.active {
    animation: pulse 0.5s infinite alternate;
}

@keyframes pulse {
    from { transform: scale(1); }
    to { transform: scale(1.1); }
}

/* Sudoku Board */
.board-container {
    position: relative;
    width: min(95vw, 55vh);
    height: min(95vw, 55vh);
    max-width: 500px;
    margin: 5px auto;
    padding: 0;
    flex-shrink: 0;
}

#sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    width: 100%;
    height: 100%;
    background: var(--grid-border);
    gap: 1px;
    border: 3px solid var(--grid-border);
    box-shadow: var(--theme-glow), 0 0 30px rgba(0,0,0,0.8);
    border-radius: 8px;
    overflow: hidden;
    backdrop-filter: blur(4px);
    transition: box-shadow 0.3s, border-color 0.3s;
}

.board-anim-shake {
    animation: shake 0.4s cubic-bezier(.36,.07,.19,.97) both;
}
@keyframes shake {
    10%, 90% { transform: translate3d(-2px, 0, 0); }
    20%, 80% { transform: translate3d(4px, 0, 0); }
    30%, 50%, 70% { transform: translate3d(-6px, 0, 0); }
    40%, 60% { transform: translate3d(6px, 0, 0); }
}

.cell {
    background: var(--cell-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: clamp(1.2rem, 6vw, 2.2rem);
    font-weight: 700;
    color: var(--text-main);
    cursor: pointer;
    transition: all 0.2s ease-out;
}

.cell:hover { background: rgba(var(--primary-rgb), 0.2); }
.cell.selected { background: var(--cell-selected) !important; transform: scale(1.05); z-index: 2; border-radius: 4px; box-shadow: 0 0 10px var(--grid-border); }
.cell.highlight { background: var(--cell-highlight); }
.cell.number-highlight { 
    background: rgba(255, 255, 255, 0.2); 
    text-shadow: 0 0 10px #fff, 0 0 20px #fff; 
}

.cell.given { color: var(--cell-given); font-weight: 500; }
.cell.input { color: var(--cell-input); text-shadow: 0 0 5px var(--cell-input); }
.cell.error { color: var(--cell-error); background: rgba(255, 0, 60, 0.2); text-shadow: 0 0 5px var(--cell-error); }
.cell.solved-anim { animation: solve-pop 0.4s ease-out; color: #00ff66; text-shadow: 0 0 10px #00ff66; }

@keyframes solve-pop {
    0% { transform: scale(0.5); opacity: 0; }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); opacity: 1; }
}

/* Thick Borders for 3x3 blocks */
.cell.border-right { border-right: 2px solid var(--grid-border); }
.cell.border-bottom { border-bottom: 2px solid var(--grid-border); }

/* Controls */
.controls-container {
    width: 100%;
    max-width: 450px;
    padding: 5px 10px;
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex-shrink: 1;
}

.numpad {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 6px;
}

.num-key {
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.02));
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: #fff;
    font-size: 1.6rem;
    padding: 10px 0;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.3);
}
.num-key:active, .action-key:active { 
    background: rgba(255, 255, 255, 0.2); 
    transform: translateY(2px);
    box-shadow: 0 2px 3px rgba(0,0,0,0.3);
}

.action-pad {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}

#btn-solve:not(.hidden) {
    grid-template-columns: 1fr 1fr 1fr;
}

.action-key {
    padding: 14px;
    font-size: 1.2rem;
    background: rgba(0, 0, 0, 0.6);
    border: 1px solid;
    color: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.3);
}
.action-key.erase { border-color: #aaa; color: #aaa; }
.action-key.hint { border-color: #ffaa00; color: #ffaa00; text-shadow: 0 0 5px rgba(255,170,0,0.5); }
.action-key.solve { border-color: #b026ff; color: #b026ff; }

.game-actions {
    display: flex;
    justify-content: center;
}

/* Tutorial Box */
#tutorial-overlay {
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    background: rgba(0, 0, 0, 0.85);
    border: 1px solid var(--primary-color);
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 0 20px rgba(0, 240, 255, 0.5);
    z-index: 50;
    width: 80%;
}
#tutorial-text { font-size: 1.2rem; margin-bottom: 15px; }

/* Responsive adjustments */
@media (max-width: 400px) {
    .logo h1 { font-size: 3rem; }
    .subtitle { font-size: 1.2rem; }
}

@media (max-height: 700px) {
    /* Tight fit for very short phones */
    #gameplay { padding: 5px; justify-content: flex-start; gap: 5px; }
    .num-key { padding: 6px 0; font-size: 1.4rem; }
    .action-key { padding: 10px; font-size: 1rem; }
}

@media (min-width: 768px) {
    #gameplay {
        display: grid;
        grid-template-areas: 
            "hud controls"
            "board controls";
        grid-template-columns: auto 320px;
        grid-template-rows: auto auto;
        gap: 15px 40px;
        justify-content: center;
        align-content: center;
        padding: 20px;
    }
    .hud { 
        grid-area: hud; 
        max-width: none; 
        margin: 0;
        width: min(65vh, 65vw);
    }
    .board-container { 
        grid-area: board; 
        width: min(65vh, 65vw); 
        height: min(65vh, 65vw); 
        max-width: 650px; 
        max-height: 650px;
        margin: 0;
    }
    .controls-container { 
        grid-area: controls; 
        height: 100%; 
        justify-content: center; 
        gap: 20px;
    }
    .numpad { grid-template-columns: repeat(3, 1fr); gap: 15px; }
    .num-key { padding: 20px 0; font-size: 2.2rem; }
    .action-pad { grid-template-columns: 1fr; }
    .action-key { padding: 18px; font-size: 1.3rem; }
}