:root {
    --bg-color: #1a1a1a;
    --accent-color: #00ffcc;
    --accent-glow: 0 0 10px #00ffcc, 0 0 20px #00ffcc;
    --text-color: #e0e0e0;
    --panel-bg: rgba(0, 0, 0, 0.85);
}

body {
    margin: 0;
    padding: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Roboto Mono', monospace;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    touch-action: none;
}

#game-container {
    position: relative;
    width: 100%;
    max-width: 600px;
    height: 100vh;
    /* Mobile full height */
    overflow: hidden;
    background: #0f0f0f;
    box-shadow: 0 0 50px rgba(0, 0, 0, 0.5);
}

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

/* UI Overlay — container only, children are absolutely positioned */
#ui-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 5;
}

#ui-overlay>* {
    pointer-events: auto;
}

/* LEVEL — top left */
#level-display {
    position: absolute;
    top: 12px;
    left: 16px;
    font-family: 'Orbitron', sans-serif;
    font-size: 18px;
    color: #00ffcc;
    text-shadow: 0 0 10px rgba(0, 255, 204, 0.5);
    white-space: nowrap;
    pointer-events: none;
}

/* SCORE — top center */
#score-display {
    position: absolute;
    top: 12px;
    left: 50%;
    transform: translateX(-50%);
    font-family: 'Orbitron', sans-serif;
    font-size: 18px;
    color: #00ffcc;
    text-shadow: 0 0 10px rgba(0, 255, 204, 0.5);
    white-space: nowrap;
    pointer-events: none;
}

/* Mute button — top right */
.icon-btn {
    position: absolute;
    top: 10px;
    right: 16px;
    background: transparent;
    border: none;
    color: #00ffcc;
    font-size: 22px;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.2s, transform 0.1s;
    padding: 0;
    margin: 0;
    line-height: 1;
    pointer-events: auto;
}

.icon-btn:hover {
    opacity: 1;
    transform: scale(1.1);
}

#ui-overlay>* {
    pointer-events: auto;
}

/* Timer bar — below the top labels */
#timer-container {
    position: absolute;
    top: 44px;
    left: 16px;
    right: 16px;
    height: 10px;
    background: #333;
    border: 1px solid #555;
    border-radius: 5px;
    overflow: hidden;
}

#timer-bar {
    width: 100%;
    height: 100%;
    background: #00ffcc;
    transition: width 0.1s linear;
}

.icon-btn:active {
    transform: scale(0.95);
}

/* Screens */
.screen {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.95);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 10;
    transition: opacity 0.3s ease;
}

.hidden {
    display: none !important;
    opacity: 0;
    pointer-events: none;
}

h1 {
    font-family: 'Orbitron', sans-serif;
    font-size: 3rem;
    color: #fff;
    text-shadow: var(--accent-glow);
    margin-bottom: 1rem;
    text-align: center;
}

p {
    margin-bottom: 2rem;
    color: #aaa;
    text-align: center;
    max-width: 80%;
}

.btn-primary,
.btn-secondary {
    background: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
    padding: 15px 40px;
    font-family: 'Orbitron', sans-serif;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.2s;
    text-transform: uppercase;
    box-shadow: 0 0 10px rgba(0, 255, 204, 0.2);
    margin-top: 20px;
}

.btn-primary:hover {
    background: var(--accent-color);
    color: #000;
    box-shadow: var(--accent-glow);
}

.btn-secondary {
    font-size: 1rem;
    padding: 10px 20px;
    margin-top: 0;
    border-color: #aaa;
    color: #aaa;
    box-shadow: none;
}

.btn-secondary:hover {
    border-color: var(--accent-color);
    color: var(--accent-color);
}

#equation-result {
    font-family: 'Roboto Mono', monospace;
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--accent-color);
}

/* Leaderboard */
#leaderboard-container {
    margin-top: 30px;
    width: 80%;
    max-width: 400px;
    background: rgba(255, 255, 255, 0.05);
    padding: 20px;
    border-radius: 10px;
    text-align: center;
}

#leaderboard-container h3 {
    margin-top: 0;
    color: var(--accent-color);
    font-family: 'Orbitron', sans-serif;
    font-size: 1.2rem;
    border-bottom: 1px solid #333;
    padding-bottom: 10px;
}

#leaderboard-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 10px;
    font-size: 0.9rem;
}

#leaderboard-table th {
    color: #888;
    text-align: left;
    padding: 5px;
    font-size: 0.8rem;
}

#leaderboard-table th.align-right {
    text-align: right;
}

#leaderboard-table th.align-left {
    text-align: left;
}

#leaderboard-table td {
    padding: 8px 5px;
    border-bottom: 1px solid #222;
}

#leaderboard-table td:nth-child(1) {
    color: #555;
    width: 30px;
}

#leaderboard-table td:nth-child(2) {
    color: #fff;
    font-weight: bold;
    text-align: left;
}

#leaderboard-table td:nth-child(3) {
    color: var(--accent-color);
    text-align: right;
}

#score-submission {
    display: flex;
    gap: 10px;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

#player-name {
    background: transparent;
    border: 2px solid #555;
    color: #fff;
    padding: 10px;
    font-family: 'Orbitron', sans-serif;
    font-size: 1.2rem;
    width: 250px;
    text-align: center;
    text-transform: uppercase;
}

#player-name:focus {
    outline: none;
    border-color: var(--accent-color);
}

#submission-msg {
    color: var(--accent-color);
    font-size: 0.9rem;
    margin-bottom: 15px;
}