:root {
    --bg-color: #050510;
    --acc-color: #00ffff;
    --acc-glow: rgba(0, 255, 255, 0.5);
    --warn-color: #ff0055;
    --warn-glow: rgba(255, 0, 85, 0.5);
    --text-color: #ffffff;
    --glass-bg: rgba(10, 10, 25, 0.7);
    --glass-border: rgba(0, 255, 255, 0.2);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    user-select: none;
    font-family: 'Orbitron', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    width: 100vw;
}

#game-container {
    position: relative;
    width: 100%;
    height: 100%;
    max-width: 1200px;
    max-height: 800px;
    background-color: #000;
    box-shadow: 0 0 50px rgba(0, 255, 255, 0.1);
    overflow: hidden;
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
}

#ui-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 10;
}

.hidden {
    display: none !important;
}

.screen {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    pointer-events: auto;
    text-align: center;
}

h1 {
    font-size: 4rem;
    font-weight: 900;
    color: var(--acc-color);
    text-shadow: 0 0 20px var(--acc-glow), 0 0 40px var(--acc-glow);
    margin-bottom: 20px;
    letter-spacing: 4px;
}

p {
    font-size: 1.2rem;
    color: #aaddff;
    margin-bottom: 40px;
    letter-spacing: 2px;
}

button {
    padding: 15px 40px;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--bg-color);
    background: var(--acc-color);
    border: none;
    border-radius: 4px;
    cursor: pointer;
    box-shadow: 0 0 15px var(--acc-glow);
    transition: all 0.2s ease;
    text-transform: uppercase;
    font-family: 'Orbitron', sans-serif;
}

button:hover {
    transform: scale(1.05);
    box-shadow: 0 0 30px var(--acc-glow), inset 0 0 10px rgba(255, 255, 255, 0.5);
    background: #ffffff;
}

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

#game-over-screen h1 {
    color: var(--warn-color);
    text-shadow: 0 0 20px var(--warn-glow), 0 0 40px var(--warn-glow);
}

#game-over-screen p {
    font-size: 2rem;
    color: #ffffff;
}

.high-score-container {
    font-size: 1.2rem;
    color: var(--acc-color);
    margin-bottom: 40px;
}

/* HUD */
#hud {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    padding: 20px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.hud-top, .hud-bottom {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
}

.hud-top {
    align-items: flex-start;
}

.score-container, .wave-container, .weapon-container {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--acc-color);
    text-shadow: 0 0 10px var(--acc-glow);
    background: rgba(0, 0, 0, 0.5);
    padding: 10px 20px;
    border-radius: 4px;
    border: 1px solid var(--glass-border);
}

.health-bar-container {
    position: relative;
    width: 300px;
    height: 30px;
    background: rgba(255, 0, 85, 0.2);
    border: 2px solid var(--warn-color);
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 0 10px var(--warn-glow);
}

#health-bar-fill {
    width: 100%;
    height: 100%;
    background: var(--warn-color);
    box-shadow: 0 0 20px var(--warn-color);
    transition: width 0.1s linear, background-color 0.2s;
}

#health-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 1rem;
    font-weight: 700;
    color: white;
    text-shadow: 1px 1px 2px black;
}

.shake {
    animation: shake 0.5s cubic-bezier(.36,.07,.19,.97) both;
}

@keyframes shake {
    10%, 90% { transform: translate3d(-1px, 0, 0); }
    20%, 80% { transform: translate3d(2px, 0, 0); }
    30%, 50%, 70% { transform: translate3d(-4px, 0, 0); }
    40%, 60% { transform: translate3d(4px, 0, 0); }
}

@media (max-width: 768px) {
    h1 { font-size: 2.5rem; }
    .score-container, .wave-container, .weapon-container { font-size: 1rem; }
    .health-bar-container { width: 200px; }
}