/* Base Reset and Roots */
:root {
    --bg-gradient: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.15);
    --btn-bg: rgba(255, 255, 255, 0.1);
    --btn-hover: rgba(255, 255, 255, 0.2);
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.5);
    --accent-glow: #00d2ff;
    --accent-gradient: linear-gradient(135deg, #00d2ff, #3a7bd5);
    --action-color: #ffb703;
    --clear-color: #ef233c;
}

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

body {
    font-family: 'Outfit', sans-serif;
    background: var(--bg-gradient);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-primary);
    overflow: hidden;
}

/* Background blob decorations */
body::before, body::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    z-index: -1;
}

body::before {
    width: 400px;
    height: 400px;
    background: rgba(58, 123, 213, 0.3);
    top: -100px;
    left: -100px;
}

body::after {
    width: 300px;
    height: 300px;
    background: rgba(0, 210, 255, 0.2);
    bottom: -50px;
    right: -50px;
}

.calculator-container {
    width: 100%;
    max-width: 360px;
    padding: 20px;
    z-index: 10;
}

.calculator-glass {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: 32px;
    border: 1px solid var(--glass-border);
    box-shadow: 0 30px 60px rgba(0, 0, 0, 0.4), inset 0 1px 0 rgba(255, 255, 255, 0.1);
    padding: 30px 24px;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.display {
    width: 100%;
    text-align: right;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    min-height: 90px;
    word-wrap: break-word;
    word-break: break-all;
    padding: 0 10px;
}

.previous-operand {
    color: var(--text-secondary);
    font-size: 1.2rem;
    font-weight: 300;
    min-height: 24px;
    margin-bottom: 4px;
}

.current-operand {
    color: var(--text-primary);
    font-size: 3rem;
    font-weight: 500;
    line-height: 1;
    letter-spacing: -1px;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
}

.btn {
    cursor: pointer;
    border: none;
    outline: none;
    font-family: 'Outfit', sans-serif;
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--text-primary);
    background: var(--btn-bg);
    border-radius: 18px;
    height: 64px;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.25s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(255,255,255, 0.05);
}

.btn:hover {
    background: var(--btn-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

.btn:active {
    transform: scale(0.95);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.span-2 {
    grid-column: span 2;
    border-radius: 32px;
    justify-content: flex-start;
    padding-left: 32px;
}

.btn.action {
    color: var(--action-color);
    background: rgba(255, 183, 3, 0.1);
}

.btn.action:hover {
    background: rgba(255, 183, 3, 0.2);
}

.btn.clear {
    color: var(--clear-color);
    background: rgba(239, 35, 60, 0.1);
}

.btn.clear:hover {
    background: rgba(239, 35, 60, 0.2);
}

.btn.equals.accent {
    background: var(--accent-gradient);
    color: #fff;
    box-shadow: 0 8px 20px rgba(0, 210, 255, 0.3);
    border: none;
}

.btn.equals.accent:hover {
    box-shadow: 0 12px 25px rgba(0, 210, 255, 0.4);
    transform: translateY(-2px);
}

.btn.equals.accent:active {
    transform: scale(0.95);
}