*, *::before, *::after { 
    box-sizing: border-box; 
}

body { 
    background: #020617; 
    color: #fff; 
    font-family: 'Inter', sans-serif; 
    display: flex; 
    flex-direction: column; 
    align-items: center; 
    justify-content: center; 
    min-height: 100vh; 
    margin: 0; 
    text-align: center; 
    overflow: hidden; 
}

#particles { 
    position: fixed; 
    inset: 0; 
    z-index: 0; 
    pointer-events: none; 
}

.bg-glow { 
    position: fixed; 
    inset: 0; 
    background: radial-gradient(ellipse 80% 60% at 50% 40%, #1e3a8a44 0%, transparent 70%); 
    z-index: 0; 
    pointer-events: none; 
}

.back-home { 
    position: fixed; 
    top: 20px; 
    left: 24px; 
    font-size: 0.85rem; 
    color: #475569; 
    text-decoration: none; 
    transition: color 0.2s; 
    z-index: 10; 
}

.back-home:hover { 
    color: #fff; 
}

.container { 
    position: relative; 
    z-index: 1; 
    display: flex; 
    flex-direction: column; 
    align-items: center; 
    padding: 40px 24px; 
    max-width: 560px; 
    width: 100%; 
}

h1 { 
    font-family: 'Syne', sans-serif; 
    font-size: clamp(2rem, 8vw, 3rem); 
    font-weight: 900; 
    margin: 0 0 6px; 
    letter-spacing: -2px; 
}

.subtitle { 
    font-size: 0.95rem; 
    color: #64748b; 
    margin-bottom: 36px; 
}

.level-badge { 
    font-size: 0.75rem; 
    font-weight: 700; 
    text-transform: uppercase; 
    letter-spacing: 2px; 
    color: #60a5fa; 
    margin-bottom: 12px; 
}

/* Number display */
.number-display {
    font-family: 'Syne', sans-serif;
    font-size: clamp(3rem, 14vw, 6rem);
    font-weight: 900; 
    letter-spacing: 6px; 
    line-height: 1;
    color: #f8fafc; 
    margin-bottom: 12px;
    min-height: 1.2em;
    transition: opacity 0.3s, transform 0.3s;
}

.number-display.hidden { 
    opacity: 0; 
    transform: scale(0.9); 
}

/* Countdown */
.countdown { 
    font-family: 'Syne', sans-serif; 
    font-size: 1.1rem; 
    font-weight: 700; 
    color: #475569; 
    margin-bottom: 32px; 
    min-height: 24px; 
}

.countdown.urgent { 
    color: #f87171; 
}

/* Input */
.input-wrap { 
    width: 100%; 
    margin-bottom: 16px; 
    position: relative; 
}

.num-input {
    width: 100%; 
    padding: 16px 20px;
    background: rgba(30, 58, 138, 0.2); 
    border: 1.5px solid rgba(96, 165, 250, 0.3);
    border-radius: 14px; 
    color: #fff;
    font-family: 'Syne', sans-serif; 
    font-size: 1.8rem; 
    font-weight: 700;
    text-align: center; 
    outline: none; 
    letter-spacing: 4px;
    transition: border-color 0.2s, background 0.2s;
}

.num-input:focus { 
    border-color: #60a5fa; 
}

.num-input.correct { 
    border-color: #10b981; 
    background: rgba(16, 185, 129, 0.1); 
}

.num-input.wrong { 
    border-color: #ef4444; 
    background: rgba(239, 68, 68, 0.1); 
    animation: inputShake 0.3s ease; 
}

@keyframes inputShake { 
    0%, 100% { transform: translateX(0); } 
    25% { transform: translateX(-8px); } 
    75% { transform: translateX(8px); } 
}

.submit-btn {
    width: 100%; 
    padding: 14px;
    background: rgba(37, 99, 235, 0.25); 
    border: 1.5px solid rgba(96, 165, 250, 0.4);
    border-radius: 14px; 
    color: #fff;
    font-family: 'Syne', sans-serif; 
    font-size: 1rem; 
    font-weight: 700;
    cursor: pointer; 
    transition: background 0.2s; 
    margin-bottom: 24px;
}

.submit-btn:hover { 
    background: rgba(37, 99, 235, 0.45); 
}

.submit-btn:disabled { 
    opacity: 0.3; 
    cursor: default; 
}

.feedback { 
    font-size: 1rem; 
    min-height: 24px; 
    transition: color 0.3s; 
}

.feedback.good { 
    color: #10b981; 
}

.feedback.bad { 
    color: #f87171; 
}

.best-row { 
    margin-top: 24px; 
    font-size: 0.85rem; 
    color: #334155; 
}

.best-row span { 
    color: #60a5fa; 
    font-weight: 700; 
}

.gameover { 
    position: fixed; 
    inset: 0; 
    background: rgba(2, 6, 23, 0.92); 
    display: flex; 
    flex-direction: column; 
    align-items: center; 
    justify-content: center; 
    z-index: 50; 
    opacity: 0; 
    pointer-events: none; 
    transition: opacity 0.4s; 
    backdrop-filter: blur(8px); 
}

.gameover.show { 
    opacity: 1; 
    pointer-events: all; 
}

.go-emoji { 
    font-size: 4rem; 
    margin-bottom: 12px; 
}

.go-title { 
    font-family: 'Syne', sans-serif; 
    font-size: clamp(1.8rem, 7vw, 2.8rem); 
    font-weight: 900; 
    margin: 0 0 8px; 
}

.go-sub { 
    color: #64748b; 
    font-size: 1rem; 
    margin-bottom: 6px; 
}

.go-answer { 
    color: #f87171; 
    font-size: 0.9rem; 
    margin-bottom: 24px; 
    font-family: 'Syne', sans-serif; 
    font-weight: 700; 
    letter-spacing: 3px; 
}

.go-btn { 
    padding: 13px 36px; 
    background: rgba(37, 99, 235, 0.3); 
    border: 1.5px solid rgba(96, 165, 250, 0.45); 
    border-radius: 999px; 
    color: #fff; 
    font-family: 'Syne', sans-serif; 
    font-size: 1rem; 
    font-weight: 700; 
    cursor: pointer; 
}

.go-btn:hover { 
    background: rgba(37, 99, 235, 0.5); 
}