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

.background-design {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: 0;
    background: linear-gradient(135deg, #1e3a8a 0%, #7c3aed 100%);
    overflow: hidden;
}

body {
    min-height: 100vh;
    position: relative;
    z-index: 1;
}

.admin-panel-btn {
    position: fixed;
    top: 30px;
    right: 40px;
    z-index: 10;
    background: linear-gradient(135deg, #ff6b6b, #ee5a52);
    color: white;
    border: none;
    padding: 12px 28px;
    border-radius: 10px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
    transition: all 0.3s;
}
.admin-panel-btn:hover {
    background: linear-gradient(135deg, #ee5a52, #ff6b6b);
    transform: translateY(-2px);
}

.admin-modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(30, 58, 138, 0.7);
    z-index: 100;
    justify-content: center;
    align-items: center;
}
.admin-modal-content {
    background: rgba(255,255,255,0.95);
    border-radius: 18px;
    padding: 40px 32px 32px 32px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.25);
    min-width: 340px;
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.admin-modal-content h2 {
    color: #333;
    font-size: 1.8em;
    margin-bottom: 25px;
    font-weight: 600;
}

.admin-modal-content .input-group {
    width: 100%;
    margin-bottom: 15px;
}

.admin-modal-content .input-group input {
    width: 100%;
    height: 50px;
    background: rgba(255, 255, 255, 0.9);
    border: 2px solid rgba(0, 212, 255, 0.3);
    border-radius: 10px;
    padding: 0 20px;
    font-size: 1.1em;
    color: #333;
    transition: all 0.3s ease;
    box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.1);
}

.admin-modal-content .input-group input:focus {
    outline: none;
    border-color: #00d4ff;
    background: rgba(255, 255, 255, 1);
    box-shadow: 0 0 0 3px rgba(0, 212, 255, 0.2);
}

.admin-modal-content .input-group input::placeholder {
    color: #999;
}
.close-modal {
    position: absolute;
    top: 18px;
    right: 22px;
    font-size: 1.5em;
    color: #ff6b6b;
    cursor: pointer;
    font-weight: bold;
    transition: color 0.2s;
}
.close-modal:hover {
    color: #d32f2f;
}
.modal-login-btn {
    width: 100%;
    height: 45px;
    background: linear-gradient(135deg, #00d4ff, #00b8e6);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 18px;
    box-shadow: 0 4px 15px rgba(0, 212, 255, 0.3);
}
.modal-login-btn:hover {
    background: linear-gradient(135deg, #00b8e6, #00d4ff);
    transform: translateY(-2px);
}

.calculator-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    z-index: 2;
    position: relative;
}

.calculator {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.2);
    width: 350px;
}

.display {
    margin-bottom: 20px;
}

.display input {
    width: 100%;
    height: 80px;
    background: rgba(255, 255, 255, 0.9);
    border: none;
    border-radius: 15px;
    font-size: 2.5em;
    text-align: right;
    padding: 0 20px;
    color: #333;
    box-shadow: inset 0 5px 15px rgba(0, 0, 0, 0.1);
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
}

.buttons button {
    height: 70px;
    border: none;
    border-radius: 15px;
    font-size: 1.5em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    background: rgba(255, 255, 255, 0.9);
    color: #333;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.buttons button:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
    background: rgba(255, 255, 255, 1);
}

.buttons button:active {
    transform: translateY(0);
}

.buttons button.equals {
    background: linear-gradient(135deg, #667eea, #764ba2);
    color: white;
    grid-row: span 2;
}

.buttons button.zero {
    grid-column: span 2;
}

.buttons button:nth-child(1),
.buttons button:nth-child(2) {
    background: rgba(255, 107, 107, 0.9);
    color: white;
}

.buttons button:nth-child(3),
.buttons button:nth-child(4) {
    background: rgba(255, 193, 7, 0.9);
    color: white;
}