/* General Styles */
:root {
    /* Refined Palette Example (Adjust as needed) */
    --primary-color: #007bff; /* Header Blue */
    --secondary-color: #6c757d; /* Grey for less important actions */
    --success-color: #28a745; /* Green */
    --danger-color: #dc3545; /* Red */
    --warning-color: #ffc107; /* Yellow */
    --info-color: #17a2b8; /* Teal */
    --light-color: #f8f9fa; /* Very light grey */
    --dark-color: #343a40; /* Dark text/elements */
    --background-color: #f0f2f5; /* Slightly softer background */
    --card-background: #ffffff;
    --card-border: #dee2e6; /* Lighter border */
    --text-color: #212529; /* Slightly darker text */
    --muted-text-color: #6c757d;
    --link-color: #0056b3;
    --border-radius: 5px; /* Slightly softer radius */
    --box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
    --box-shadow-hover: 0 3px 8px rgba(0, 0, 0, 0.1);
    --drop-indicator-color: var(--primary-color); /* Color for the drop indicator line */
    --layout-gap: 1.5rem; /* Define gap size */
}

html, body {
    height: 100%;
    margin: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
}


/* --- Sign-in Screen Styles --- */

#sign-in-container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    flex-grow: 1;
    padding: 20px;
    width: 100%;
    box-sizing: border-box;
    background-color: var(--background-color);
}

.sign-in-box {
    background-color: var(--card-background);
    padding: 30px 40px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow-hover);
    border: 1px solid var(--card-border);
    text-align: center;
    max-width: 400px;
    width: 100%;
    box-sizing: border-box;
}
/* Removed logo style */
.sign-in-box h2 {
    font-size: 1.6rem; font-weight: 600; margin-bottom: 0.5rem; color: var(--dark-color);
}
.sign-in-box p {
    margin-bottom: 1.5rem; color: var(--muted-text-color); font-size: 0.95rem;
}
.dummy-email-form { display: flex; flex-direction: column; gap: 0.8rem; }
#dummy-email-input { width: 100%; text-align: left; font-size: 1rem; }
.remember-me { display: flex; align-items: center; justify-content: flex-start; gap: 0.5rem; margin-top: 0.5rem; margin-bottom: 1rem; }
.remember-me input[type="checkbox"] { width: auto; margin: 0; accent-color: var(--primary-color); }
.remember-me label { font-size: 0.9rem; color: var(--muted-text-color); cursor: pointer; margin-bottom: 0; }
#dummy-proceed-button { width: 100%; padding: 0.7rem 1rem; font-size: 1rem; font-weight: 600; background-color: var(--primary-color); color: white; }
#dummy-proceed-button:hover { filter: brightness(90%); }
.error-message { color: var(--danger-color); font-size: 0.85rem; margin-top: 0.5rem; min-height: 1.2em; font-weight: 500; }
.sign-in-notice { font-size: 0.8rem; color: var(--muted-text-color); margin-top: 1.5rem; margin-bottom: 0; }

/* --- Main App Container --- */
#app-container { display: none; flex-direction: column; width: 100%; min-height: 100%; }

/* --- App Styles --- */

header { background-color: var(--primary-color); color: #fff; padding: 1.2rem 2rem; text-align: center; box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); flex-shrink: 0; }
header h1 { margin: 0; font-size: 1.8rem; font-weight: 600; }
header p { margin: 0.3rem 0 0; font-size: 0.95rem; opacity: 0.9; }
#user-info { font-size: 0.8em; margin-top: 5px; opacity: 0.8; }

main { padding: 1.5rem 2rem; max-width: 1400px; margin: 1.5rem auto; width: 100%; box-sizing: border-box; flex-grow: 1; }

button { padding: 0.4rem 0.8rem; border: 1px solid transparent; border-radius: var(--border-radius); cursor: pointer; font-size: 0.85rem; font-weight: 500; transition: all 0.2s ease; margin-left: 5px; background-color: var(--secondary-color); color: white; vertical-align: middle; line-height: 1.4; }
button:hover { filter: brightness(90%); transform: translateY(-1px); box-shadow: 0 2px 4px rgba(0,0,0,0.1); }
button:active { filter: brightness(80%); transform: translateY(0px); box-shadow: none; }
button.icon-btn { padding: 0.4rem 0.5rem; font-size: 1rem; line-height: 1; }

input[type="text"], input[type="url"], input[type="search"], input[type="email"], textarea { padding: 0.6rem 0.8rem; border: 1px solid #ced4da; border-radius: var(--border-radius); font-size: 0.9rem; width: 100%; margin-bottom: 0; box-sizing: border-box; transition: border-color 0.2s ease, box-shadow 0.2s ease; }
input:focus, textarea:focus { border-color: var(--primary-color); box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25); outline: none; }
input[type="search"] { -webkit-appearance: none; appearance: none; }
textarea { resize: vertical; min-height: 70px; }

a { color: var(--link-color); text-decoration: none; transition: color 0.2s ease; }
a:hover { color: var(--primary-color); text-decoration: underline; }

/* Toolbar */
.toolbar { display: flex; flex-wrap: wrap; gap: 1rem; background-color: var(--card-background); padding: 1rem 1.5rem; border-radius: var(--border-radius); margin-bottom: 2rem; box-shadow: var(--box-shadow); align-items: center; }
.add-category-section { display: flex; align-items: center; flex: 1 1 300px; gap: 0.5rem; }
.add-category-section input[type="text"] { width: auto; flex-grow: 1; }
#add-category-btn { background-color: var(--success-color); flex-shrink: 0; }
.search-section { flex: 2 1 400px; }
.search-section input[type="search"] { width: 100%; }
.io-section { display: flex; gap: 0.5rem; flex-shrink: 0; }
#export-data-btn, #import-data-btn { background-color: var(--info-color); }

/* Status Message */
.status-message { font-size: 0.9em; color: var(--muted-text-color); margin: -1.5rem 0 1.5rem 0.5rem; min-height: 1.2em; }

/* Categories Container - Flexbox Layout */
#categories-container {
    display: flex;
    flex-wrap: wrap;
    gap: var(--layout-gap); /* Use variable for gap */
    align-items: stretch; /* Stretch items for more consistent height */
    /* Removed grid properties */
    /* padding: 1px; /* No longer needed for margin collapse */
}
@media (max-width: 768px) {
    #categories-container {
        gap: 1rem; /* Adjust gap for mobile */
         /* Flex wrap handles single column automatically */
    }
    .toolbar { flex-direction: column; align-items: stretch; }
    .add-category-section, .search-section, .io-section { flex-basis: auto; width: 100%; }
    .io-section { justify-content: flex-end; }
    .sign-in-box { padding: 20px; }
}

/* Category Styling - Flexbox Basis */
.category {
    background-color: var(--card-background); border-radius: var(--border-radius);
    box-shadow: var(--box-shadow); border: 1px solid var(--card-border);
    display: flex; flex-direction: column;
    transition: box-shadow 0.2s ease, border-top-width 0.15s ease-out;
    /* Calculate basis for 2 columns, accounting for the main gap */
    flex-basis: calc(50% - (var(--layout-gap) / 2));
    flex-grow: 1; /* Allow growing */
    box-sizing: border-box;
    margin: 0; /* Remove margins, rely on gap */
    position: relative;
    border-top-width: 1px; /* Default border top */
}
.category:hover { box-shadow: var(--box-shadow-hover); }

@media (max-width: 768px) {
    .category {
        flex-basis: 100%; /* Full width on mobile */
    }
}

.category-header { display: flex; align-items: center; border-bottom: 1px solid var(--card-border); padding: 0.7rem 1rem; background-color: #f8f9fa; border-radius: var(--border-radius) var(--border-radius) 0 0; }
.category-header h2 { margin: 0; font-size: 1.15rem; font-weight: 600; color: var(--dark-color); flex-grow: 1; margin-left: 0.5rem; margin-right: 1rem; line-height: 1.4; user-select: text; }
.category-controls { display: flex; align-items: center; white-space: nowrap; margin-left: auto; gap: 4px; }
.category-controls button { font-size: 0.8rem; }
.category-controls .sort-toggle-btn { background-color: #e9ecef; color: var(--dark-color); border: 1px solid #ced4da; padding: 0.3rem 0.6rem; min-width: 45px; text-align: center; }
.category-controls .sort-toggle-btn:hover { filter: brightness(95%); }
.category-controls .edit-category-btn { background-color: var(--warning-color); color: var(--dark-color); }
.category-controls .delete-category-btn { background-color: var(--danger-color); }
.category-controls .add-card-btn { background-color: var(--info-color); }

/* Drag Handles */
.drag-handle { cursor: grab; padding: 0.3rem; font-size: 1.1rem; color: var(--muted-text-color); background-color: transparent; border: none; line-height: 1; user-select: none; border-radius: 3px; transition: background-color 0.2s ease, color 0.2s ease; display: flex; align-items: center; justify-content: center; width: 24px; height: 24px; }
.drag-handle:hover { background-color: rgba(0,0,0,0.08); color: var(--dark-color); opacity: 1; }
.drag-handle:active { cursor: grabbing; background-color: rgba(0,0,0,0.12); }
.category-drag-handle { margin-left: -5px; }
.card-drag-handle { margin-left: auto; }

/* Cards Container */
.cards-container { padding: 1rem; display: grid; grid-template-columns: 1fr; gap: 0.8rem; min-height: 50px; flex-grow: 1; /* Allow card container to grow vertically */ }

/* Card Styling */
.card { background-color: #fff; border: 1px solid #e9ecef; border-radius: var(--border-radius); padding: 0.8rem 1rem; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05); transition: box-shadow 0.2s ease; display: flex; flex-direction: column; }
.card:hover { box-shadow: 0 2px 5px rgba(0, 0, 0, 0.08); }
.card-header { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 0.6rem; }
.card h3 { margin: 0; font-size: 1.05rem; font-weight: 600; flex-grow: 1; margin-right: 0.5rem; line-height: 1.4; user-select: text; }
.card h3 a { color: var(--text-color); }
.card h3 a:hover { color: var(--primary-color); }
.card p.card-description { margin: 0 0 0.8rem 0; font-size: 0.85rem; color: var(--muted-text-color); flex-grow: 1; user-select: text; line-height: 1.5; }
.card-tags { margin-bottom: 0.8rem; display: flex; flex-wrap: wrap; gap: 0.3rem; }
.card-tag { background-color: var(--secondary-color); opacity: 0.8; color: white; padding: 0.1rem 0.4rem; border-radius: 3px; font-size: 0.7rem; font-weight: 500; display: inline-block; }
.card-controls { display: flex; justify-content: flex-end; margin-top: auto; gap: 4px; }
.card-controls button { font-size: 0.8rem; }
.card-controls .edit-card-btn { background-color: var(--warning-color); color: var(--dark-color); }
.card-controls .delete-card-btn { background-color: #e57373; color: white; }

/* Empty State Messages */
.empty-state-message, .empty-category-message { text-align: center; color: var(--muted-text-color); padding: 2rem 1rem; font-style: italic; font-size: 0.9rem; grid-column: 1 / -1; border: 2px dashed var(--card-border); border-radius: var(--border-radius); margin-top: 0.5rem; }
.empty-category-message { margin: 0.5rem; }

/* Drag and Drop Visual Feedback */
.dragging { outline: 2px dashed var(--primary-color); outline-offset: 2px; z-index: 10; opacity: 1; box-shadow: var(--box-shadow); background-color: var(--card-background); }
.dragging .drag-handle { cursor: grabbing; }

/* Card Drag Over */
.drag-over { background-color: #e7f3ff; outline: 2px dashed var(--primary-color); outline-offset: -4px; }
.drag-over .empty-category-message { display: none; }

/* Category Drop Indicator */
.category.drop-indicator-before { border-top: 4px solid var(--drop-indicator-color); }
/* Reset border needed when indicator removed */
.category { border-top-width: 1px; }

/* Modal Styles */
.modal { display: none; position: fixed; z-index: 1000; left: 0; top: 0; width: 100%; height: 100%; overflow: auto; background-color: rgba(0,0,0,0.5); backdrop-filter: blur(2px); }
.modal-content { background-color: #fefefe; margin: 8% auto; padding: 20px 30px 30px 30px; border: none; width: 90%; max-width: 500px; border-radius: var(--border-radius); box-shadow: 0 5px 15px rgba(0,0,0,0.3); position: relative; animation: fadeInModal 0.3s ease-out; }
@keyframes fadeInModal { from { opacity: 0; transform: translateY(-20px); } to { opacity: 1; transform: translateY(0); } }
.modal-content h2 { margin-top: 0; color: var(--dark-color); border-bottom: 1px solid #dee2e6; padding-bottom: 0.8rem; margin-bottom: 1.5rem; font-size: 1.4rem; font-weight: 600; }
.modal-content label { display: block; margin-bottom: 0.4rem; font-weight: 500; font-size: 0.85rem; color: var(--muted-text-color); }
.modal-content input, .modal-content textarea { margin-bottom: 1rem; font-size: 0.9rem; }
.modal-actions { display: flex; justify-content: flex-end; gap: 0.5rem; margin-top: 1.5rem; padding-top: 1rem; border-top: 1px solid #eee; }
#save-category-btn, #save-card-btn { background-color: var(--success-color); }
#confirm-modal-confirm-btn { background-color: var(--danger-color); }
.modal-content .cancel-btn, #confirm-modal-cancel-btn { background-color: var(--secondary-color); }
.close-btn { color: #aaa; position: absolute; top: 10px; right: 15px; font-size: 24px; font-weight: bold; background: none; border: none; padding: 0 5px; line-height: 1; cursor: pointer; }
.close-btn:hover, .close-btn:focus { color: black; }

/* Toast Notification Styles */
#toast-container { position: fixed; bottom: 20px; right: 20px; z-index: 2000; display: flex; flex-direction: column; gap: 0.5rem; align-items: flex-end; }
.toast { background-color: var(--dark-color); color: white; padding: 0.7rem 1.1rem; border-radius: var(--border-radius); box-shadow: 0 3px 10px rgba(0,0,0,0.2); font-size: 0.9rem; opacity: 0; transform: translateX(110%); transition: opacity 0.3s ease, transform 0.4s cubic-bezier(0.25, 1, 0.5, 1); }
.toast.show { opacity: 1; transform: translateX(0); }
.toast.success { background-color: var(--success-color); }
.toast.error { background-color: var(--danger-color); }
.toast.info { background-color: var(--info-color); }

/* Accessibility */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border-width: 0; }