* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    position: relative;
    border: none;
    outline: none;
    font-family: 'Tektur', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f5f5f5;
    color: #333;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 350px;
    background-color: white;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

header {
    background-color: #4a6fa5;
    color: white;
    padding: 15px 20px;
    text-align: center;
}

h1 {
    margin-bottom: 0;
    font-size: 24px;
}

.display {
    background-color: #f0f2f5;
    padding: 20px;
    text-align: right;
    font-size: 28px;
    font-weight: bold;
    min-height: 80px;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    word-break: break-all;
    border-bottom: 1px solid #eee;
}

.buttons-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
    padding: 15px;
}

.btn {
    padding: 15px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.primary {
    background-color: #4a6fa5;
    color: white;
}

.primary:hover:not(:disabled) {
    background-color: #3a5b87;
}

.secondary {
    background-color: #e0e0e0;
    color: #333;
}

.secondary:hover:not(:disabled) {
    background-color: #d0d0d0;
}

.danger {
    background-color: #ff4d4d;
    color: white;
}

.danger:hover:not(:disabled) {
    background-color: #e04444;
}

.warning {
    background-color: #ffa500;
    color: white;
}

.warning:hover:not(:disabled) {
    background-color: #e09400;
}

.span-2 {
    grid-column: span 2;
}

.ms-1 {
    margin-left: 8px;
}

.notification {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    padding: 10px 20px;
    background-color: #4a6fa5;
    color: white;
    border-radius: 5px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
    opacity: 0;
    transition: opacity 0.3s ease;
    z-index: 1000;
    pointer-events: none;
}

.notification.show {
    opacity: 1;
    pointer-events: unset;
}

@media (max-width: 400px) {
    .container {
        max-width: 95%;
    }

    .btn {
        padding: 12px;
        font-size: 16px;
    }
}