:root {
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --glass-bg: rgba(255, 255, 255, 0.95);
    --primary: #6c5ce7;
    --accent: #00cec9;
    --text: #2d3436;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Inter', sans-serif;
}

body {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    
    background-image: linear-gradient(rgba(0, 0, 0, 0.4), rgba(0, 0, 0, 0.4)), 
                      url('1.webp');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    
    padding: 20px;
}

.glass-wrapper {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    width: 100%;
    max-width: 380px;
    padding: 30px;
    border-radius: 30px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.3);
}

header { text-align: center; margin-bottom: 20px; }
h1 { font-size: 1.8rem; color: var(--text); }
h1 span { color: var(--primary); }
.subtitle { font-size: 0.8rem; color: #636e72; letter-spacing: 1px; }

.display-area {
    background: #f1f2f6;
    padding: 20px;
    border-radius: 15px;
    text-align: right;
    margin-bottom: 20px;
    min-height: 80px;
}

#previous-op { font-size: 0.9rem; color: #b2bec3; height: 1.2rem; }
#display { font-size: 2rem; font-weight: 700; color: var(--text); word-wrap: break-word; }

.keypad {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}

.btn {
    border: none;
    padding: 18px 0;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 500;
    cursor: pointer;
    background: #fff;
    color: var(--text);
    transition: all 0.2s ease;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.btn:hover { transform: translateY(-2px); box-shadow: 0 6px 12px rgba(0,0,0,0.1); }
.btn:active { transform: translateY(0); }

.btn-op { background: #f9f9ff; color: var(--primary); font-weight: 700; }
.btn-util { color: #eb4d4b; }
.btn-equals { background: var(--primary); color: white; grid-column: span 1; }
.btn-zero { grid-column: span 1; }

.info-card {
    margin-top: 25px;
    padding-top: 20px;
    border-top: 1px solid #dfe6e9;
}

.info-card h3 { font-size: 1rem; margin-bottom: 10px; }
.info-card ul { list-style: none; font-size: 0.85rem; color: #636e72; }
.info-card li { margin-bottom: 5px; }