:root {
    --bg-gradient-start: #6dd5ed;
    --bg-gradient-end: #2193b0;

    --l-circle-gradient-start: #ff758c;
    --l-circle-gradient-end: #ff7eb3;

    --r-circle-gradient-start: #4facfe;
    --r-circle-gradient-end: #00f2fe;

    --timer-gradient-start: #4facfe;
    --timer-gradient-end: #00f2fe;

    --difficulty-active-color: #ff758c;

    --pop-success-duration: 0.3s;
    --shake-error-duration: 0.5s;
    --countdown-pop-duration: 1s;
}

body {
    font-family: 'Montserrat', sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start), var(--bg-gradient-end));
    background-size: 200% 200%;
    animation: gradientShift 15s ease infinite;
    overflow: hidden;
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path fill="rgba(255,255,255,0.8)" stroke="black" stroke-width="1" d="M5.5 3.42L18.42 12 5.5 20.58V3.42z"/></svg>'), auto;
}
@keyframes gradientShift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}
.title {
    text-shadow: 2px 2px 0px rgba(0,0,0,0.1);
}
.game-card {
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.8);
    box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.2);
}
.game-board {
    cursor: crosshair;
}
.target-circle {
    position: absolute;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: 700;
    color: white;
    transition: transform 0.2s ease;
    user-select: none;
    border: 3px solid rgba(255, 255, 255, 0.5);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.15);
    text-shadow: 1px 1px 2px rgba(0,0,0,0.3);
}
.target-circle:hover {
    transform: scale(1.1);
    z-index: 10;
}
.l-circle { background: linear-gradient(135deg, var(--l-circle-gradient-start), var(--l-circle-gradient-end)); }
.r-circle { background: linear-gradient(135deg, var(--r-circle-gradient-start), var(--r-circle-gradient-end)); }

@keyframes pop-success {
    0% { transform: scale(1); }
    50% { transform: scale(1.2); }
    100% { transform: scale(0) rotate(90deg); opacity: 0; }
}
.pop-success-animation { animation: pop-success var(--pop-success-duration) ease-out forwards; }

@keyframes shake-error {
     0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-8px); }
    20%, 40%, 60%, 80% { transform: translateX(8px); }
}
.shake-error-animation { animation: shake-error var(--shake-error-duration); }

.timer-bar-container {
    background: rgba(0,0,0,0.1);
    border-radius: 10px;
}
.timer-bar-fill {
    height: 10px;
    background: linear-gradient(90deg, var(--timer-gradient-start), var(--timer-gradient-end));
    border-radius: 10px;
    transition: width 1s linear;
}
.countdown-number {
    font-weight: 700;
    color: #2193b0;
    text-shadow: 3px 3px 0px rgba(255,255,255,0.8);
    animation: countdown-pop var(--countdown-pop-duration) ease-in-out;
}
@keyframes countdown-pop {
    0% { transform: scale(0.5); opacity: 0; }
    80% { transform: scale(1.2); opacity: 1; }
    100% { transform: scale(1); opacity: 1; }
}
.difficulty-btn.active {
    background-color: var(--difficulty-active-color);
    color: white;
    box-shadow: 0 0 10px var(--difficulty-active-color);
}