@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

:root {
    --primary-color: #007bff;
    --primary-color-dark: #0056b3;
    --secondary-color: #4A5568;
    --text-color-light: #718096;
    --background-color: #F0F4F8;
    --apple-interface-background: #F5F5F7;
    --apple-modal-background: #FFFFFF;
    --surface-color: #FFFFFF;
    --border-color: #D1D1D6;
    --light-grey: #E2E8F0;
    --danger-color: #e53e3e;
    --warning-color: #FFA500;
    --success-color: #28A745;
    --auth-accent-color: var(--primary-color);
    --auth-accent-color-dark: var(--primary-color-dark);

    --transaction-sale-color: #28a745;
    --transaction-add-color: #007bff;
    --transaction-update-color: #ffc107;
    --transaction-delete-color: #dc3545;
    
    --alert-expiry-warning-color: #FFA500;
    --alert-expiry-critical-color: #e53e3e;
    --alert-restock-color: #f0ad4e;
    --inventory-item-color: #6c757d;

    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 18px;

    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.03);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.06);
    --shadow-xl: 0 15px 30px rgba(0,0,0,0.08);
    
    --input-height: 44px;
}

* {
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

html {
    overflow-x: hidden;
    max-width: 100vw;
}

body {
    font-family: var(--font-family);
    margin: 0;
    background-color: var(--background-color);
    color: var(--secondary-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    font-size: 16px; 
    line-height: 1.6;
    overflow-x: hidden;
    max-width: 100%;
    overscroll-behavior: contain;
}

header {
    background-color: rgba(255, 255, 255, 0.65); 
    color: var(--secondary-color); 
    padding: 14px 20px; 
    text-align: center;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05); 
    position: sticky;
    top: 0;
    z-index: 1000;
    -webkit-backdrop-filter: blur(8px); 
    backdrop-filter: blur(8px); 
}

header h1 {
    margin: 0;
    font-size: 1.25em; 
    font-weight: 600; 
    letter-spacing: 0.5px; 
}

main#app-container {
    flex-grow: 1;
    padding: 20px;
    padding-bottom: 90px; 
    overflow-x: hidden;
}

main#app-container > div:not(.auth-view) h2 {
    color: var(--secondary-color);
    font-size: 1.6em; 
    font-weight: 600;
    margin-top: 0;
    margin-bottom: 24px; 
}

h3 {
    font-size: 1.25em;
    font-weight: 600;
    color: var(--secondary-color);
    margin-bottom: 12px;
}

h4 {
    font-size: 1.05em;
    font-weight: 500;
    color: var(--secondary-color);
    margin-bottom: 8px;
}

.hidden {
    display: none !important;
}

/* Forms */
form {
    background-color: var(--surface-color);
    padding: 20px;
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
}

form div {
    margin-bottom: 18px; 
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500; 
    font-size: 0.9em;
    color: var(--text-color-light);
}

input[type="text"],
input[type="number"],
input[type="date"],
input[type="email"],
input[type="password"],
select { 
    width: 100%; 
    padding: 0 12px; 
    height: var(--input-height);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    font-size: 1em;
    background-color: var(--surface-color);
    color: var(--secondary-color);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.2); 
}

/* Buttons */
.big-button {
    display: block;
    width: 100%;
    padding: 0 20px;
    height: 52px;
    line-height: 52px;
    font-size: 1.05em;
    font-weight: 600;
    color: var(--surface-color);
    background-color: var(--primary-color);
    border: none;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    text-align: center;
    margin-top: 12px;
    transition: background-color 0.2s ease, transform 0.1s ease, box-shadow 0.2s ease;
    box-shadow: var(--shadow-sm);
    text-decoration: none;
}
.big-button:hover {
    background-color: var(--primary-color-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}
.big-button:active {
    transform: translateY(0px);
    box-shadow: var(--shadow-xs);
}
.big-button.secondary {
    background-color: var(--light-grey);
    color: var(--secondary-color);
    border: 1px solid var(--border-color);
}
.big-button.secondary:hover {
    background-color: var(--border-color);
}
.big-button.success { 
    background-color: var(--success-color);
}
.big-button.success:hover {
    background-color: #218838;
}
.big-button.danger {
    background-color: var(--danger-color);
    color: var(--surface-color);
}
.big-button.danger:hover {
    background-color: #c82333; 
}
.big-button:disabled {
    background-color: var(--light-grey) !important;
    color: #aaa !important;
    cursor: not-allowed !important;
    box-shadow: none !important;
    transform: none !important;
}

.small-button { 
    padding: 8px 14px; 
    font-size: 0.9em;
    font-weight: 500;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    background-color: var(--light-grey);
    color: var(--secondary-color);
    border: 1px solid var(--border-color);
    transition: background-color 0.2s ease;
    text-align: center; 
    display: inline-block; 
}
.small-button:hover { background-color: var(--border-color); }
.small-button.secondary { background-color: var(--surface-color); border: 1px solid var(--border-color); color: var(--text-color-light); }
.small-button.secondary:hover { background-color: var(--light-grey); }
.small-button.success { background-color: var(--success-color); color: #fff; border: none; }
.small-button.danger { background-color: var(--danger-color); color: #fff; border: none; }
.small-button.warning { background-color: var(--warning-color); color: #fff; border: none; }

.link-button { 
    background: none;
    border: none;
    color: var(--primary-color);
    text-decoration: none; 
    cursor: pointer;
    padding: 4px; 
    font-size: inherit; 
    font-weight: 500;
}
.link-button:hover { color: #0056b3; }

.icon-button {
    background: none;
    border: none;
    padding: 6px;
    font-size: 1.4em;
    line-height: 1;
    cursor: pointer;
    color: var(--text-color-light);
    border-radius: 50%;
    width: 36px;
    height: 36px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s ease;
}
.icon-button:hover { background-color: var(--light-grey); }

.fab {
    position: fixed;
    bottom: 80px; 
    right: 20px;
    width: 56px;
    height: 56px;
    background-color: var(--primary-color);
    color: var(--surface-color);
    border-radius: 50%; 
    border: none;
    box-shadow: var(--shadow-lg);
    font-size: 24px; 
    line-height: 56px; 
    text-align: center;
    cursor: pointer;
    z-index: 1050; 
    transition: background-color 0.2s ease, transform 0.2s ease;
}
.fab:hover { background-color: var(--primary-color-dark); transform: scale(1.05); }
.fab:active { transform: scale(0.95); }

/* Navigation */
#bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: rgba(255, 255, 255, 0.65); 
    display: flex;
    justify-content: space-around;
    padding: 8px 0; 
    border-top: 1px solid rgba(0, 0, 0, 0.05); 
    height: 65px; 
    -webkit-backdrop-filter: blur(8px); 
    backdrop-filter: blur(8px);
    z-index: 1000; 
}
.nav-button {
    background: none;
    border: none;
    color: var(--text-color-light); 
    padding: 8px 12px;
    font-size: 0.8em; 
    font-weight: 500;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    flex-grow: 1; 
    transition: color 0.2s ease;
}
.nav-icon { font-size: 24px; margin-bottom: 4px; line-height: 1; }
.nav-text { font-size: 0.75em; line-height: 1.2; }
.nav-button.active { color: var(--primary-color); font-weight: 600; }
.nav-button:hover { color: var(--primary-color); }

/* Modals */
.modal {
    position: fixed;
    z-index: 1050;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0s linear 0.3s;
}
.modal.is-open { opacity: 1; visibility: visible; transition: opacity 0.3s ease; }
.modal-content {
    background-color: var(--surface-color);
    padding: 25px;
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-xl);
    max-width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    transform: scale(0.95);
    transition: transform 0.3s ease;
}
.modal.is-open .modal-content { transform: scale(1); }
.modal-close-button {
    position: absolute;
    top: 10px;
    right: 15px;
    font-size: 1.8em;
    font-weight: bold;
    color: var(--text-color-light);
    background: none;
    border: none;
    cursor: pointer;
}

/* Toast Notifications */
#toast-container {
    position: fixed;
    top: 20px; 
    right: 20px; 
    z-index: 2000; 
    display: flex;
    flex-direction: column;
    align-items: flex-end; 
    gap: 10px;
}
.toast {
    background-color: var(--secondary-color);
    color: var(--surface-color);
    padding: 12px 20px;
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transform: translateX(100%); 
    transition: opacity 0.3s ease, transform 0.3s ease;
    font-size: 0.9em;
    font-weight: 500;
    min-width: 200px;
    text-align: center;
}
.toast.show { opacity: 1; transform: translateX(0); }
.toast.success { background-color: var(--success-color); }
.toast.error { background-color: var(--danger-color); }
.toast.warning { background-color: var(--warning-color); color: var(--secondary-color); }

@media (min-width: 768px) {
    main#app-container {
        max-width: 700px;
        margin-left: auto;
        margin-right: auto;
        padding: 24px 24px 90px 24px;
    }
    .big-button { max-width: 320px; margin-left: auto; margin-right: auto; }
}