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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #0a0a0a;
    color: #ffffff;
    min-height: 100vh;
    overflow-x: hidden;
}

.stars {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(2px 2px at 20px 30px, #eee, transparent),
        radial-gradient(2px 2px at 40px 70px, rgba(255,255,255,0.8), transparent),
        radial-gradient(1px 1px at 90px 40px, #fff, transparent),
        radial-gradient(1px 1px at 130px 80px, rgba(255,255,255,0.6), transparent),
        radial-gradient(2px 2px at 160px 30px, #ddd, transparent);
    background-repeat: repeat;
    background-size: 200px 100px;
    animation: twinkle 3s infinite;
}

@keyframes twinkle {
    0%, 100% { opacity: 0.8; }
    50% { opacity: 1; }
}

.container {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 2rem;
}

.title {
    font-size: 3rem;
    margin-bottom: 2rem;
    background: linear-gradient(45deg, #00ffff, #ff00ff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 0 30px rgba(0, 255, 255, 0.5);
    animation: glow 2s ease-in-out infinite alternate;
}

@keyframes glow {
    from { filter: brightness(1); }
    to { filter: brightness(1.2); }
}

.mode-selector {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
}

.mode-btn {
    padding: 0.75rem 2rem;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 25px;
    color: #ffffff;
    cursor: pointer;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.mode-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 255, 255, 0.3);
}

.mode-btn.active {
    background: linear-gradient(45deg, #00ffff, #ff00ff);
    border-color: transparent;
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.5);
}

.calculator {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

.hidden {
    display: none;
}

.input-group {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: rgba(255, 255, 255, 0.05);
    padding: 1.5rem;
    border-radius: 15px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.input-field {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 8px;
    padding: 0.75rem;
    color: #ffffff;
    font-size: 1.2rem;
    text-align: center;
    width: 100px;
    transition: all 0.3s ease;
}

.input-field:focus {
    outline: none;
    background: rgba(255, 255, 255, 0.2);
    border-color: #00ffff;
    box-shadow: 0 0 10px rgba(0, 255, 255, 0.5);
}

.input-field::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

.multiply {
    font-size: 1.5rem;
    color: #00ffff;
    font-weight: bold;
}

.base-size {
    margin-left: 1rem;
    width: 80px;
}

.preview-square {
    width: 200px;
    height: 150px;
    background: linear-gradient(135deg, rgba(0, 255, 255, 0.2), rgba(255, 0, 255, 0.2));
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 10px;
    transition: all 0.3s ease;
    box-shadow: 0 0 30px rgba(0, 255, 255, 0.3);
}

.preview-square:hover {
    transform: scale(1.05);
    box-shadow: 0 0 40px rgba(0, 255, 255, 0.5);
}

.fullscreen-btn {
    padding: 1rem 2rem;
    background: linear-gradient(45deg, #00ffff, #ff00ff);
    border: none;
    border-radius: 25px;
    color: #0a0a0a;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 5px 15px rgba(0, 255, 255, 0.3);
}

.fullscreen-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(0, 255, 255, 0.5);
}

.fullscreen-btn:active {
    transform: translateY(-1px);
}

.fullscreen-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #0a0a0a;
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.fullscreen-overlay.show {
    display: flex;
}

.fullscreen-overlay:fullscreen {
    background: #000;
}

.fullscreen-overlay:-webkit-full-screen {
    background: #000;
}

.fullscreen-overlay:-moz-full-screen {
    background: #000;
}

.fullscreen-overlay:fullscreen .fullscreen-square {
    max-width: 95vw;
    max-height: 95vh;
}

.fullscreen-square {
    background: linear-gradient(135deg, rgba(0, 255, 255, 0.3), rgba(255, 0, 255, 0.3));
    border: 2px solid rgba(255, 255, 255, 0.5);
    box-shadow: 0 0 50px rgba(0, 255, 255, 0.5);
}

.exit-btn {
    position: absolute;
    top: 2rem;
    right: 2rem;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    color: #ffffff;
    font-size: 1.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.exit-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: rotate(90deg);
}

.info-text {
    font-size: 1.1rem;
    color: #00ffff;
    text-align: center;
    margin: 0.5rem 0;
    font-family: 'Courier New', monospace;
}

@media (max-width: 768px) {
    .title {
        font-size: 2rem;
    }
    
    .input-group {
        flex-direction: column;
        gap: 1rem;
    }
    
    .preview-square {
        width: 150px;
        height: 100px;
    }
}