:root {
    --bg-color: #ffffff;
    --card-bg: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    --gradient-hover: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
    --border-color: #e2e8f0;
    --input-bg: #f8fafc;
    --error-color: #ef4444;
    --radius-sm: 10px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.02);
    --shadow-md: 0 8px 20px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 16px 32px rgba(0, 0, 0, 0.06);
    --shadow-hover: 0 20px 40px rgba(99, 102, 241, 0.1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    background-image: radial-gradient(circle at top right, rgba(139, 92, 246, 0.04), transparent 400px),
                      radial-gradient(circle at bottom left, rgba(99, 102, 241, 0.04), transparent 400px);
    min-height: 100vh;
}

.container {
    width: 100%;
    padding: 2rem 5%;
}

header {
    text-align: center;
    margin-bottom: 4rem;
    animation: fadeInDown 0.8s ease-out;
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

h1 {
    font-size: 3rem;
    font-weight: 800;
    color: var(--text-main);
    margin-bottom: 0.75rem;
    letter-spacing: -0.04em;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
}

.subtitle {
    color: var(--text-muted);
    font-size: 1.15rem;
    font-weight: 500;
}

/* Instructions */
.instructions-card {
    margin-bottom: 3.5rem;
    padding-left: 1.5rem;
    border-left: 4px solid var(--primary-color);
}

.instructions-card h3 {
    color: var(--text-main);
    margin-bottom: 1.25rem;
    font-size: 1.25rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.instructions-card ol {
    margin-left: 1.25rem;
    color: var(--text-muted);
}

.instructions-card li {
    margin-bottom: 0.75rem;
    line-height: 1.7;
}

.instructions-card li strong {
    color: var(--text-main);
}

.instructions-note {
    margin-top: 1.5rem;
    font-size: 0.9rem;
    color: var(--primary-color);
    background: rgba(99, 102, 241, 0.05);
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    display: inline-block;
}

/* Forms */
.input-section {
    padding: 1rem 0;
}

.form-group {
    margin-bottom: 2rem;
}

.form-group:last-child {
    margin-bottom: 0;
}

.form-row {
    display: flex;
    gap: 1.5rem;
    align-items: flex-end;
}

.form-row .form-group {
    flex: 1;
    margin-bottom: 0;
}

label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-main);
    font-size: 0.95rem;
}

.help-text {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 1.25rem;
}

textarea, input[type="number"] {
    width: 100%;
    padding: 1rem 1.25rem;
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 1rem;
    color: var(--text-main);
    transition: all 0.3s ease;
    background-color: var(--input-bg);
}

textarea:focus, input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
    background-color: var(--card-bg);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

textarea {
    resize: vertical;
    line-height: 1.6;
}

/* Buttons */
.btn-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: var(--gradient-primary);
    color: white;
    font-weight: 600;
    padding: 0 2rem;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
    height: 52px;
}

.btn-primary:hover {
    background: var(--gradient-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(99, 102, 241, 0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background-color: var(--card-bg);
    color: var(--text-main);
    font-weight: 600;
    padding: 0.75rem 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    background-color: rgba(99, 102, 241, 0.02);
}

/* Category Columns */
.category-columns {
    display: flex;
    gap: 1.5rem;
    overflow-x: auto;
    padding-bottom: 1rem;
    margin-bottom: 1.5rem;
    scrollbar-width: thin;
    scrollbar-color: var(--border-color) transparent;
}

.category-columns::-webkit-scrollbar {
    height: 6px;
}

.category-columns::-webkit-scrollbar-track {
    background: transparent;
}

.category-columns::-webkit-scrollbar-thumb {
    background-color: var(--border-color);
    border-radius: 10px;
}

.category-columns::-webkit-scrollbar-thumb:hover {
    background-color: var(--text-muted);
}

.category-column {
    flex: 1;
    min-width: 280px;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    transition: all 0.3s ease;
}

.category-column:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
}

.category-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.75rem;
}

.category-name-wrapper {
    position: relative;
    flex-grow: 1;
    cursor: text;
}

.category-name-input {
    font-weight: 600;
    font-size: 1.05rem;
    border: 1px dashed transparent;
    background-color: transparent;
    padding: 0.5rem 2rem 0.5rem 0.5rem;
    width: 100%;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
    color: var(--text-main);
}

.category-name-input:focus, .category-name-input:hover {
    border-color: var(--border-color);
    background-color: var(--input-bg);
    outline: none;
}

.category-name-input:focus {
    border-color: var(--primary-color);
    border-style: solid;
}

.edit-icon {
    position: absolute;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    cursor: pointer;
    transition: color 0.2s ease;
}

.edit-icon:hover,
.category-name-input:focus + .edit-icon {
    color: var(--primary-color);
}

.btn-remove {
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.4rem;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.btn-remove:hover {
    background-color: #fee2e2;
    color: var(--error-color);
}

.category-textarea {
    flex-grow: 1;
    min-height: 180px;
    border: none;
    background-color: var(--input-bg);
}

/* Results Section */
.results-section {
    margin-top: 4rem;
    animation: fadeIn 0.6s ease-out forwards;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.results-section h2 {
    font-size: 1.75rem;
    color: var(--text-main);
    font-weight: 700;
    letter-spacing: -0.02em;
}

.groups-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

.group-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    overflow: hidden;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.group-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
    border-color: rgba(99, 102, 241, 0.2);
}

.group-header {
    background: transparent;
    color: var(--text-main);
    padding: 1.5rem 1.5rem 1rem;
    font-weight: 700;
    font-size: 1.15rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
}

.group-title-area {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.group-count-badge {
    background: var(--input-bg);
    color: var(--text-muted);
    padding: 0.25rem 0.75rem;
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 600;
    border: 1px solid var(--border-color);
}

.btn-copy {
    background: var(--input-bg);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.btn-copy:hover {
    background: white;
    color: var(--primary-color);
    border-color: var(--primary-color);
    transform: scale(1.05);
}

.btn-copy:active {
    transform: scale(0.95);
}

.btn-copy.copied {
    background: #10b981;
    color: white;
    border-color: #10b981;
}

.member-list {
    list-style: none;
    padding: 0.5rem 0;
    margin: 0;
    flex-grow: 1;
}

.member-item {
    padding: 0.85rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.2s ease;
}

.member-item:hover {
    background-color: var(--input-bg);
}

.member-name {
    font-weight: 500;
    color: var(--text-main);
}

.member-category {
    font-size: 0.75rem;
    color: var(--primary-color);
    background-color: rgba(99, 102, 241, 0.08);
    padding: 0.35rem 0.65rem;
    border-radius: 999px;
    font-weight: 600;
    letter-spacing: 0.02em;
}

.error-message {
    margin-top: 1.5rem;
    padding: 1rem 1.25rem;
    background-color: #fef2f2;
    border: 1px solid #fecaca;
    color: #b91c1c;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.hidden {
    display: none !important;
}

/* Footer */
footer {
    text-align: center;
    margin-top: 5rem;
    padding-top: 2rem;
    color: var(--text-muted);
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .form-row {
        flex-direction: column;
        align-items: stretch;
    }
    
    .btn-primary {
        width: 100%;
    }
    
    .category-column {
        min-width: 240px;
    }
    
    h1 {
        font-size: 2.5rem;
    }
}