:root {
    --bg-color: #0f172a;
    --text-color: #f8fafc;
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
    --accent-color: #3b82f6;
    --accent-hover: #60a5fa;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    background-image: radial-gradient(circle at top right, #1e3a8a, transparent), 
                      radial-gradient(circle at bottom left, #0f172a, #000);
    color: var(--text-color);
    height: 100vh;
    width: 100vw;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* Glass UI Layer */
#ui-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 10;
    transition: opacity 0.5s ease;
    padding: 20px;
}

#ui-layer:not(.active) {
    opacity: 0;
    pointer-events: none;
}

.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 40px;
    width: 100%;
    max-width: 400px;
    text-align: center;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    gap: 30px;
    animation: slideUp 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(40px); }
    to { opacity: 1; transform: translateY(0); }
}

.header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 8px;
    background: linear-gradient(135deg, #60a5fa, #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.header p {
    font-size: 0.95rem;
    color: #94a3b8;
    line-height: 1.5;
}

.icon-placeholder {
    font-size: 4rem;
    margin-bottom: 15px;
    filter: drop-shadow(0 0 10px rgba(96, 165, 250, 0.5));
}

.upload-section {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

/* Hide actual file input */
input[type="file"] {
    display: none;
}

/* Custom Upload Button */
.upload-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    background: rgba(255,255,255,0.05);
    border: 2px dashed rgba(255,255,255,0.2);
    border-radius: 16px;
    padding: 20px;
    width: 100%;
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-btn:hover {
    background: rgba(255,255,255,0.1);
    border-color: var(--accent-hover);
    transform: translateY(-2px);
}

.upload-btn:active {
    transform: translateY(0);
}

.btn-icon {
    font-size: 1.5rem;
}

.btn-text {
    font-weight: 600;
    font-size: 1.1rem;
}

.status {
    font-size: 0.9rem;
    color: #cbd5e1;
    min-height: 20px;
    transition: color 0.3s;
}

/* Start Button */
.start-btn {
    background: linear-gradient(135deg, var(--accent-color), #4f46e5);
    color: white;
    border: none;
    border-radius: 12px;
    padding: 15px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s, opacity 0.3s;
    box-shadow: 0 10px 20px rgba(59, 130, 246, 0.4);
}

.start-btn:hover:not(:disabled) {
    transform: translateY(-2px) scale(1.02);
    box-shadow: 0 15px 25px rgba(59, 130, 246, 0.5);
}

.start-btn:active:not(:disabled) {
    transform: translateY(1px);
}

.start-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background: #475569;
    box-shadow: none;
}

.hidden {
    display: none !important;
}

/* Iframe adjustments */
#game-frame {
    position: absolute;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    border: none;
    background: #000;
    z-index: 5;
}

/* Close Button Floating over Iframe */
#close-game-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
    border-radius: 22px;
    background: rgba(0,0,0,0.6);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid rgba(255,255,255,0.2);
    color: white;
    font-size: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    z-index: 20;
    transition: background 0.2s;
}

#close-game-btn:hover {
    background: rgba(0,0,0,0.8);
}