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

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #1e1e1e;
    overflow: hidden;
}

/* ============================= */
/* GLASSMORPHISM CALCULATOR */
/* ============================= */

.calculator {
    position: relative;
    display: grid;
    grid-template-columns: 1fr;
    width: 320px;
    border-radius: 20px;

    background: rgba(43, 43, 43, 0.6);
    backdrop-filter: blur(18px);
    -webkit-backdrop-filter: blur(18px);

    border: 1px solid rgba(255, 255, 255, 0.1);

    box-shadow:
        0 0 25px rgba(122, 92, 255, 0.2),
        0 8px 32px rgba(0, 0, 0, 0.35),
        inset 0 0 0.8px rgba(255, 255, 255, 0.2);

    overflow: hidden;
    z-index: 2;
}

/* ============================= */
/* DISPLAY */
/* ============================= */

.display {
    padding: 20px;
    text-align: right;
    background: rgba(0, 0, 0, 0.2);
}

.display input {
    width: 100%;
    border: none;
    background: transparent;
    color: #fff;
    font-size: 3em;
    text-align: right;
    padding-right: 10px;
    outline: none;
}

/* ============================= */
/* BUTTON GRID */
/* ============================= */

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 2px;
}

/* NORMAL BUTTON */
.buttons button {
    padding: 20px;
    background: rgba(60, 60, 60, 0.85);
    border: none;
    color: #fff;
    font-size: 1.5em;
    cursor: pointer;
    position: relative;
    overflow: hidden;

    transition: all 0.25s ease-in-out;
}

/* GLOW EFFECT */
.buttons button::before {
    content: "";
    position: absolute;
    inset: -2px;
    background: linear-gradient(
        45deg,
        #00f5a0,#7bd0fa,
        #7a5cff,
        #ff5ccf
    );
    opacity: 0;
    transition: 0.4s;
    z-index: -1;
    filter: blur(12px);
}

.buttons button:hover::before {
    opacity: 1;
}

.buttons button:hover {
    transform: translateY(-2px) scale(1.02);
    background: rgba(90, 90, 90, 0.95);
}

.buttons button:active {
    transform: scale(0.95);
}

/* ============================= */
/* OPERATORS & EQUALS */
/* ============================= */

.operator,
.equals {
    background: rgba(255, 111, 97, 0.85);
    font-weight: bold;
}

.operator:hover,
.equals:hover {
    background: #ff6f61;
    box-shadow: 
        0 0 15px #ff6f61,
}

.operator:active,
.equals:active {
    background: #ff9a8f;
}

/* ============================= */
/* LEFT & RIGHT DECOR TEXT */
/* ============================= */

.bg-decor-left,
.bg-decor-right {
    position: absolute;
    top: 50%;
    transform: translateY(-50%) rotate(-90deg);
    font-size: 4.6rem;
    font-weight: 900;
    letter-spacing: 0.08em;
    white-space: nowrap;
    pointer-events: none;
    z-index: 0;

    opacity: 0.22;

    background-image: linear-gradient(
        90deg,
        #00f5a0,
        #00c2ff,
        #7a5cff,
        #ff5ccf
    );
    background-size: 400% 400%;

    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;

    text-shadow:
        0 0 12px rgba(0, 245, 160, 0.35),
        0 0 22px rgba(0, 194, 255, 0.25),
        0 0 32px rgba(122, 92, 255, 0.2);

    animation: 
        decorShift 16s ease infinite, 
        decorPulse 6s ease-in-out infinite,
        sideFloat 8s ease-in-out infinite;
}

.bg-decor-left { 
    left: 6%; 
    font-size: 4.4rem;
}

.bg-decor-right { 
    right: 6%;
    font-size: 4.8rem;
}

/* ============================= */
/* ANIMATIONS */
/* ============================= */

@keyframes decorShift {
    0%   { background-position: 0% 50%; }
    50%  { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

@keyframes decorPulse {
    0%   { opacity: 0.15; }
    50%  { opacity: 0.25; }
    100% { opacity: 0.15; }
}

@keyframes sideFloat {
    0%   { transform: translateY(-50%) rotate(-90deg) translateY(0); }
    50%  { transform: translateY(-50%) rotate(-90deg) translateY(-10px); }
    100% { transform: translateY(-50%) rotate(-90deg) translateY(0); }
}

/* ============================= */
/* RESPONSIVENESS */
/* ============================= */

@media (max-width: 900px) {
    .bg-decor-left,
    .bg-decor-right {
        display: none;
    }
}

@media (max-width: 480px) {
    .calculator {
        width: 280px;
    }
}

/* ============================= */
/* REDUCE MOTION SUPPORT */
/* ============================= */

@media (prefers-reduced-motion: reduce) {
    .bg-decor-left,
    .bg-decor-right {
        animation: none;
    }

    .buttons button {
        transition: none;
    }
}