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

:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;
    --border: #334155;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
}

[data-theme="light"] {
    --primary: #4f46e5;
    --primary-dark: #4338ca;
    --primary-light: #6366f1;
    --bg-primary: #f1f5f9;
    --bg-secondary: #ffffff;
    --bg-tertiary: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-tertiary: #64748b;
    --border: #cbd5e1;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

[data-theme="light"] body {
    background: linear-gradient(135deg, #f1f5f9 0%, #e2e8f0 100%);
}

[data-theme="light"] h1 {
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

[data-theme="light"] .split-result {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.08) 0%, rgba(129, 140, 248, 0.04) 100%);
    border-color: rgba(99, 102, 241, 0.2);
}

[data-theme="light"] .result-row {
    border-bottom-color: rgba(99, 102, 241, 0.1);
}

[data-theme="light"] .total-row {
    border-top-color: rgba(99, 102, 241, 0.2);
}

[data-theme="light"] .remainder-row {
    background: rgba(99, 102, 241, 0.06);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    color: var(--text-primary);
    line-height: 1.6;
    padding: 20px;
    min-height: 100vh;
}

.container {
    max-width: 700px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 40px;
    padding-top: 20px;
}

.logo {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    border-radius: 16px;
    margin-bottom: 16px;
    box-shadow: var(--shadow-lg);
}

.logo svg {
    width: 32px;
    height: 32px;
    color: white;
}

h1 {
    background: linear-gradient(135deg, var(--primary-light) 0%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 2.25rem;
    font-weight: 800;
    margin-bottom: 8px;
    letter-spacing: -0.025em;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

.card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 32px;
    margin-bottom: 24px;
    box-shadow: var(--shadow-xl);
    backdrop-filter: blur(10px);
}

.input-group {
    margin-bottom: 28px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

input[type="number"],
input[type="text"] {
    width: 100%;
    padding: 14px 16px;
    background: var(--bg-tertiary);
    border: 2px solid transparent;
    border-radius: 10px;
    font-size: 1.125rem;
    color: var(--text-primary);
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

input[type="number"]:focus,
input[type="text"]:focus {
    outline: none;
    border-color: var(--primary);
    background: var(--bg-secondary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

input::placeholder {
    color: var(--text-tertiary);
}

.presets-section {
    margin-bottom: 28px;
}

.presets-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.presets-header h3 {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    font-weight: 600;
}

.preset-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    min-height: 44px;
}

.preset-chip {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 14px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 20px;
    font-size: 0.875rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
}

.preset-chip:hover {
    background: var(--bg-primary);
    border-color: var(--primary);
    color: var(--text-primary);
    transform: translateY(-1px);
}

.preset-chip-delete {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 16px;
    height: 16px;
    background: transparent;
    border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    font-size: 16px;
    line-height: 1;
    padding: 0;
    transition: color 0.2s;
}

.preset-chip-delete:hover {
    color: var(--danger);
}

.empty-presets {
    color: var(--text-tertiary);
    font-size: 0.875rem;
    font-style: italic;
    text-align: center;
    padding: 12px;
}

.quick-split-section {
    margin-bottom: 28px;
}

.quick-split-header {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    font-weight: 600;
    margin-bottom: 12px;
}

.quick-split-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.quick-split-chip {
    display: inline-flex;
    align-items: center;
    padding: 8px 16px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border: none;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    color: white;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: var(--shadow-sm);
}

.quick-split-chip:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.quick-split-chip:active {
    transform: translateY(0);
}

.splits-section {
    margin-top: 28px;
}

.splits-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}

.splits-header h2 {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    font-weight: 600;
}

.btn-group {
    display: flex;
    gap: 8px;
}

.btn {
    padding: 10px 18px;
    border: none;
    border-radius: 8px;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

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

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--primary);
}

.btn-danger {
    background: transparent;
    color: var(--text-tertiary);
    padding: 8px;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-danger:hover {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger);
}

.btn-icon {
    padding: 10px;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.split-item {
    display: grid;
    grid-template-columns: 1fr auto 100px auto;
    gap: 12px;
    align-items: center;
    margin-bottom: 12px;
    padding: 16px;
    background: var(--bg-tertiary);
    border: 1px solid transparent;
    border-radius: 12px;
    transition: all 0.2s;
}

.split-item:hover {
    border-color: var(--border);
}

.split-item input[type="text"] {
    padding: 10px 12px;
    font-size: 1rem;
}

.split-item select {
    width: 100%;
    padding: 10px 12px;
    background: var(--bg-tertiary);
    border: 2px solid transparent;
    border-radius: 10px;
    font-size: 1rem;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394a3b8' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 32px;
}

.split-item select:focus {
    outline: none;
    border-color: var(--primary);
    background-color: var(--bg-secondary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.split-item select option {
    background: var(--bg-secondary);
    color: var(--text-primary);
    padding: 8px;
}

.split-item select optgroup {
    font-weight: 600;
    color: var(--text-secondary);
}

.category-copy-btn {
    padding: 8px 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-tertiary);
    cursor: pointer;
    font-size: 0.75rem;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.category-copy-btn:hover {
    background: var(--bg-primary);
    border-color: var(--primary);
    color: var(--primary-light);
}

.category-copy-btn.copied {
    background: rgba(16, 185, 129, 0.2);
    border-color: var(--success);
    color: var(--success);
}

.split-item input[type="number"] {
    padding: 10px 12px;
    font-size: 1rem;
    text-align: center;
}

.split-result {
    margin-top: 32px;
    padding: 28px;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(129, 140, 248, 0.05) 100%);
    border-radius: 16px;
    border: 2px solid rgba(99, 102, 241, 0.3);
    opacity: 0;
    transform: translateY(10px);
    animation: fadeInUp 0.3s forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.split-result h3 {
    font-size: 0.875rem;
    color: var(--primary-light);
    margin-bottom: 20px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-weight: 700;
}

.result-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 0;
    border-bottom: 1px solid rgba(99, 102, 241, 0.15);
}

.result-row:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.result-label-group {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.result-label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 1rem;
}

.result-percent {
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

.result-amount-container {
    display: flex;
    align-items: center;
    gap: 12px;
}

.result-amount {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--primary-light);
    font-family: 'SF Mono', Monaco, 'Courier New', monospace;
    letter-spacing: -0.025em;
}

.copy-btn {
    opacity: 0;
    padding: 8px 10px;
    background: rgba(99, 102, 241, 0.2);
    border: 1px solid rgba(99, 102, 241, 0.3);
    border-radius: 6px;
    color: var(--primary-light);
    cursor: pointer;
    font-size: 0.75rem;
    font-weight: 600;
    transition: all 0.2s;
}

.result-row:hover .copy-btn {
    opacity: 1;
}

.copy-btn:hover {
    background: rgba(99, 102, 241, 0.3);
    border-color: var(--primary);
}

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

.copy-btn.copied {
    background: rgba(16, 185, 129, 0.2);
    border-color: var(--success);
    color: var(--success);
}

.total-row {
    margin-top: 16px;
    padding-top: 20px;
    border-top: 2px solid rgba(99, 102, 241, 0.3);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.total-row .result-label {
    font-weight: 800;
    font-size: 1.125rem;
}

.total-row .result-amount {
    font-size: 2.25rem;
}

.status-indicator {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 4px 10px;
    border-radius: 12px;
    margin-left: 8px;
}

.status-matched {
    background: rgba(16, 185, 129, 0.2);
    color: var(--success);
}

.status-warning {
    background: rgba(245, 158, 11, 0.2);
    color: var(--warning);
}

.remainder-row {
    background: rgba(99, 102, 241, 0.08);
    margin: 0 -28px;
    padding: 16px 28px;
    border-radius: 0;
}

.remainder-row .result-label {
    color: var(--primary-light);
    font-style: italic;
}

.remainder-row .result-percent {
    color: var(--primary-light);
    opacity: 0.7;
}

.adjust-btn {
    opacity: 0;
    padding: 6px 10px;
    background: rgba(16, 185, 129, 0.2);
    border: 1px solid rgba(16, 185, 129, 0.3);
    border-radius: 6px;
    color: var(--success);
    cursor: pointer;
    font-size: 0.7rem;
    font-weight: 600;
    transition: all 0.2s;
    white-space: nowrap;
}

.result-row:hover .adjust-btn {
    opacity: 1;
}

.adjust-btn:hover {
    background: rgba(16, 185, 129, 0.3);
    border-color: var(--success);
}

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

.toast {
    position: fixed;
    bottom: 24px;
    right: 24px;
    padding: 16px 24px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    box-shadow: var(--shadow-xl);
    display: flex;
    align-items: center;
    gap: 12px;
    transform: translateY(100px);
    opacity: 0;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 1000;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

.toast-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    color: var(--success);
}

.toast-message {
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.875rem;
}

footer {
    text-align: center;
    margin-top: 48px;
    padding: 24px;
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

.footer-tagline {
    margin-bottom: 8px;
}

.footer-disclaimer {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    opacity: 0.8;
    margin-bottom: 12px;
    font-style: italic;
}

.footer-links {
    margin-top: 8px;
}

.footer-links a {
    font-size: 0.75rem;
}

footer a {
    color: var(--primary-light);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.2s;
}

footer a:hover {
    color: var(--primary);
}

.footer-socials {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin: 16px 0;
}

.footer-socials a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.footer-socials a:hover {
    background: var(--bg-primary);
    border-color: var(--primary);
    color: var(--primary-light);
    transform: translateY(-2px);
}

.footer-socials svg {
    width: 20px;
    height: 20px;
}

/* Privacy Modal Styles */
.privacy-modal {
    max-width: 560px;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
}

.privacy-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.privacy-header h3 {
    margin: 0;
    font-size: 1.25rem;
}

.modal-close-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-tertiary);
    cursor: pointer;
    transition: all 0.2s;
}

.modal-close-btn:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--primary);
}

.privacy-content {
    flex: 1;
    overflow-y: auto;
    padding-right: 8px;
    margin-right: -8px;
}

.privacy-content::-webkit-scrollbar {
    width: 6px;
}

.privacy-content::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

.privacy-content::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

.privacy-content::-webkit-scrollbar-thumb:hover {
    background: var(--text-tertiary);
}

.privacy-updated {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    font-style: italic;
    margin-bottom: 20px;
}

.privacy-content h4 {
    font-size: 0.9rem;
    color: var(--primary-light);
    margin-top: 20px;
    margin-bottom: 10px;
    font-weight: 600;
}

.privacy-content h4:first-of-type {
    margin-top: 0;
}

.privacy-content p {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.6;
    margin-bottom: 12px;
}

.privacy-content ul {
    margin: 0 0 16px 0;
    padding-left: 20px;
}

.privacy-content li {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.6;
    margin-bottom: 8px;
}

.privacy-content li strong {
    color: var(--text-primary);
}

.privacy-footer {
    padding-top: 20px;
    border-top: 1px solid var(--border);
    margin-top: 20px;
    display: flex;
    justify-content: flex-end;
}

/* User Guide Modal Styles */
.guide-modal {
    max-width: 520px;
    max-height: 85vh;
    display: flex;
    flex-direction: column;
}

.guide-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.guide-header h3 {
    margin: 0;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.guide-content {
    flex: 1;
    overflow-y: auto;
    padding-right: 8px;
    margin-right: -8px;
}

.guide-section {
    margin-bottom: 8px;
}

.guide-step {
    display: flex;
    gap: 16px;
    margin-bottom: 20px;
}

.step-number {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 32px;
    height: 32px;
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    border-radius: 50%;
    color: white;
    font-weight: 700;
    font-size: 0.875rem;
}

.step-content h4 {
    margin: 0 0 4px 0;
    font-size: 0.95rem;
    color: var(--text-primary);
    font-weight: 600;
}

.step-content p {
    margin: 0;
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.guide-divider {
    height: 1px;
    background: var(--border);
    margin: 24px 0;
}

.guide-features-title {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-tertiary);
    margin: 0 0 16px 0;
    font-weight: 600;
}

.guide-feature {
    display: flex;
    gap: 12px;
    margin-bottom: 16px;
    align-items: flex-start;
}

.feature-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 36px;
    height: 36px;
    background: rgba(99, 102, 241, 0.1);
    border-radius: 8px;
    color: var(--primary-light);
}

.guide-feature strong {
    display: block;
    font-size: 0.9rem;
    color: var(--text-primary);
    margin-bottom: 2px;
}

.guide-feature p {
    margin: 0;
    font-size: 0.8rem;
    color: var(--text-tertiary);
    line-height: 1.4;
}

.guide-footer {
    padding-top: 20px;
    border-top: 1px solid var(--border);
    margin-top: 20px;
    display: flex;
    justify-content: flex-end;
}

/* Header controls container (help + theme toggle) */
.header-controls {
    position: absolute;
    top: 20px;
    right: 20px;
    display: flex;
    gap: 8px;
}

.help-toggle {
    padding: 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.help-toggle:hover {
    background: var(--bg-primary);
    color: var(--primary-light);
    border-color: var(--primary);
}

.help-toggle svg {
    width: 20px;
    height: 20px;
}

.theme-toggle {
    padding: 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--primary);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
}

.theme-toggle .icon-sun {
    display: none;
}

[data-theme="light"] .theme-toggle .icon-sun {
    display: block;
}

[data-theme="light"] .theme-toggle .icon-moon {
    display: none;
}

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
    padding: 20px;
}

.modal-overlay.show {
    opacity: 1;
    pointer-events: auto;
}

.modal {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 32px;
    max-width: 400px;
    width: 100%;
    box-shadow: var(--shadow-xl);
    transform: scale(0.9);
    transition: transform 0.3s;
}

.modal-overlay.show .modal {
    transform: scale(1);
}

.modal h3 {
    font-size: 1.5rem;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.modal p {
    color: var(--text-secondary);
    margin-bottom: 24px;
    font-size: 0.875rem;
}

.modal-input {
    margin-bottom: 24px;
}

.modal-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
}

@media (max-width: 640px) {
    .container {
        padding: 0;
    }

    .card {
        padding: 24px;
    }

    h1 {
        font-size: 1.875rem;
    }

    .split-item {
        grid-template-columns: 1fr auto 70px auto;
        gap: 6px;
        padding: 12px;
    }

    .result-amount {
        font-size: 1.5rem;
    }

    .total-row .result-amount {
        font-size: 1.875rem;
    }

    .toast {
        right: 12px;
        bottom: 12px;
        left: 12px;
    }
}

/* Auth UI Styles */
.auth-section {
    position: absolute;
    top: 20px;
    right: 120px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.auth-btn {
    padding: 8px 16px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.2s;
}

.auth-btn:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--primary);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.user-email {
    max-width: 150px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.sync-indicator {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 8px;
    background: rgba(16, 185, 129, 0.1);
    border-radius: 12px;
    font-size: 0.75rem;
    color: var(--success);
}

.sync-indicator.syncing {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning);
}

/* Auth Modal Styles */
.auth-modal .modal.auth-modal-content {
    max-width: 420px;
    padding: 0;
    overflow: hidden;
    border: none;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.auth-header {
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    padding: 32px 32px 28px;
    text-align: center;
}

.auth-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 64px;
    height: 64px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    margin-bottom: 16px;
    backdrop-filter: blur(10px);
}

.auth-icon svg {
    width: 32px;
    height: 32px;
    color: white;
}

.auth-header h3 {
    color: white;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 8px;
    letter-spacing: -0.025em;
}

.auth-header p {
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.875rem;
    margin: 0;
}

.auth-modal .auth-tabs {
    display: flex;
    gap: 0;
    margin: 0;
    background: var(--bg-tertiary);
    padding: 6px;
    border-radius: 0;
}

.auth-modal .auth-tab {
    flex: 1;
    padding: 12px 16px;
    background: transparent;
    border: none;
    border-radius: 8px;
    color: var(--text-tertiary);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 600;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.auth-modal .auth-tab.active {
    background: var(--bg-secondary);
    color: var(--primary-light);
    box-shadow: var(--shadow-sm);
}

.auth-modal .auth-tab:hover:not(.active) {
    color: var(--text-secondary);
    background: rgba(255, 255, 255, 0.05);
}

.auth-modal .auth-tab svg {
    opacity: 0.7;
}

.auth-modal .auth-tab.active svg {
    opacity: 1;
}

.auth-form {
    padding: 24px 32px;
}

.auth-input-group {
    margin-bottom: 20px;
}

.auth-input-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.auth-input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.auth-input-icon {
    position: absolute;
    left: 14px;
    color: var(--text-tertiary);
    pointer-events: none;
    transition: color 0.2s;
}

.auth-input-wrapper input {
    width: 100%;
    padding: 14px 16px 14px 46px;
    background: var(--bg-tertiary);
    border: 2px solid transparent;
    border-radius: 10px;
    font-size: 1rem;
    color: var(--text-primary);
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.auth-input-wrapper input:focus {
    outline: none;
    border-color: var(--primary);
    background: var(--bg-secondary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.auth-input-wrapper input:focus + .auth-input-icon,
.auth-input-wrapper:focus-within .auth-input-icon {
    color: var(--primary-light);
}

.auth-input-wrapper input::placeholder {
    color: var(--text-tertiary);
}

.forgot-password-link {
    display: inline-block;
    margin-top: 8px;
    font-size: 0.8rem;
    color: var(--text-tertiary);
    text-decoration: none;
    transition: color 0.2s;
}

.forgot-password-link:hover {
    color: var(--primary-light);
}

.auth-error {
    padding: 12px 16px;
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    border-radius: 10px;
    color: var(--danger);
    font-size: 0.875rem;
    margin: 0 32px 16px;
    display: none;
    animation: shakeError 0.4s ease-in-out;
}

@keyframes shakeError {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-5px); }
    40%, 80% { transform: translateX(5px); }
}

.auth-error.show {
    display: block;
}

.auth-success {
    padding: 12px 16px;
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.3);
    border-radius: 10px;
    color: var(--success);
    font-size: 0.875rem;
    margin: 0 32px 16px;
    display: none;
}

.auth-success.show {
    display: block;
}

.auth-actions {
    display: flex;
    gap: 12px;
    padding: 0 32px 32px;
}

.btn-auth-secondary {
    flex: 1;
    padding: 14px 20px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-auth-secondary:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
    border-color: var(--text-tertiary);
}

.btn-auth-primary {
    flex: 2;
    padding: 14px 24px;
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    border: none;
    border-radius: 10px;
    color: white;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    box-shadow: 0 4px 14px rgba(99, 102, 241, 0.4);
}

.btn-auth-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

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

.btn-auth-primary svg {
    transition: transform 0.2s;
}

.btn-auth-primary:hover svg {
    transform: translateX(3px);
}

/* Custom Categories Section */
.custom-categories-section {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
}

.custom-categories-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.custom-categories-header h3 {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    font-weight: 600;
}

.add-category-form {
    display: flex;
    gap: 8px;
    margin-bottom: 12px;
}

.add-category-form input {
    flex: 1;
    padding: 8px 12px;
    font-size: 0.875rem;
}

.custom-category-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.custom-category-chip {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: 16px;
    font-size: 0.8rem;
    color: var(--primary-light);
}

.custom-category-chip button {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 14px;
    height: 14px;
    background: transparent;
    border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    font-size: 14px;
    line-height: 1;
    padding: 0;
    transition: color 0.2s;
}

.custom-category-chip button:hover {
    color: var(--danger);
}

.empty-categories {
    color: var(--text-tertiary);
    font-size: 0.8rem;
    font-style: italic;
}

/* Default Categories */
.default-categories-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 16px;
    margin-bottom: 10px;
}

.default-categories-header h4 {
    margin: 0;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.default-categories-hint {
    font-size: 0.7rem;
    color: var(--text-tertiary);
    font-style: italic;
}

.default-category-list {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.default-category-chip {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 10px;
    background: rgba(100, 116, 139, 0.1);
    border: 1px solid rgba(100, 116, 139, 0.2);
    border-radius: 12px;
    font-size: 0.75rem;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.default-category-chip.hidden-category {
    background: rgba(239, 68, 68, 0.1);
    border-color: rgba(239, 68, 68, 0.2);
    color: var(--text-tertiary);
    text-decoration: line-through;
    opacity: 0.7;
}

.category-toggle-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 14px;
    height: 14px;
    background: transparent;
    border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    padding: 0;
    transition: color 0.2s;
}

.default-category-chip:not(.hidden-category) .category-toggle-btn:hover {
    color: var(--danger);
}

.default-category-chip.hidden-category .category-toggle-btn:hover {
    color: var(--success);
}

/* Category Settings Button */
.category-settings-btn {
    padding: 8px 12px !important;
    min-width: auto;
}

.category-settings-btn svg {
    flex-shrink: 0;
}

/* Category Settings Modal */
.category-settings-modal {
    max-width: 520px;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
}

.category-settings-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.category-settings-header h3 {
    margin: 0;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.category-settings-content {
    flex: 1;
    overflow-y: auto;
    padding-right: 8px;
    margin-right: -8px;
}

.category-settings-content::-webkit-scrollbar {
    width: 6px;
}

.category-settings-content::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

.category-settings-content::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

.category-settings-content::-webkit-scrollbar-thumb:hover {
    background: var(--text-tertiary);
}

.category-settings-section {
    margin-bottom: 24px;
}

.category-settings-section:last-child {
    margin-bottom: 0;
}

.category-settings-section h4 {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin: 0 0 12px 0;
}

.category-settings-section .custom-category-list {
    min-height: 40px;
}

.category-settings-section .default-categories-header {
    margin-top: 0;
    margin-bottom: 12px;
}

.category-settings-footer {
    padding-top: 20px;
    border-top: 1px solid var(--border);
    margin-top: 20px;
    display: flex;
    justify-content: flex-end;
}

/* Settings Row */
.settings-row {
    display: flex;
    gap: 20px;
    margin-bottom: 24px;
    flex-wrap: wrap;
}

.setting-item {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.setting-item label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-tertiary);
    margin-bottom: 0;
}

.toggle-group {
    display: flex;
    background: var(--bg-tertiary);
    border-radius: 8px;
    padding: 4px;
    gap: 4px;
}

.toggle-option {
    padding: 8px 14px;
    background: transparent;
    border: none;
    border-radius: 6px;
    color: var(--text-tertiary);
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
}

.toggle-option:hover {
    color: var(--text-secondary);
}

.toggle-option.active {
    background: var(--bg-secondary);
    color: var(--primary-light);
    box-shadow: var(--shadow-sm);
}

.toggle-option svg {
    opacity: 0.7;
}

.toggle-option.active svg {
    opacity: 1;
}

/* Split by People */
.split-by-people {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
}

.split-by-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.split-by-people input[type="number"] {
    width: 60px;
    padding: 8px 10px;
    font-size: 0.9rem;
    text-align: center;
}

.btn-split-people {
    padding: 8px 14px;
    font-size: 0.8rem;
}

.btn-split-people svg {
    flex-shrink: 0;
}

/* Keyboard Shortcuts Hint */
.keyboard-hint {
    display: none;
    position: fixed;
    bottom: 24px;
    right: 24px;
    padding: 12px 16px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 10px;
    font-size: 0.75rem;
    color: var(--text-tertiary);
    box-shadow: var(--shadow-lg);
    z-index: 100;
    align-items: center;
    gap: 12px;
}

.keyboard-hint.hidden {
    display: none !important;
}

.keyboard-hint-content {
    flex: 1;
}

.keyboard-hint-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 20px;
    height: 20px;
    padding: 0;
    background: transparent;
    border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    border-radius: 4px;
    transition: all 0.2s;
    flex-shrink: 0;
}

.keyboard-hint-close:hover {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
}

.keyboard-hint kbd {
    display: inline-block;
    padding: 2px 6px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: 4px;
    font-family: 'SF Mono', Monaco, 'Courier New', monospace;
    font-size: 0.7rem;
    color: var(--text-secondary);
    margin: 0 2px;
}

@media (min-width: 768px) {
    .keyboard-hint:not(.hidden) {
        display: flex;
    }
}

@media (max-width: 640px) {
    .settings-row {
        flex-direction: column;
        gap: 16px;
    }

    .split-by-people {
        flex-wrap: wrap;
    }
}

@media (max-width: 640px) {
    .auth-section {
        position: static;
        justify-content: center;
        margin-bottom: 12px;
    }

    /* Header controls row on mobile */
    .header-controls {
        position: static;
        justify-content: center;
        margin-bottom: 16px;
    }

    header {
        display: flex;
        flex-direction: column;
        align-items: center;
        padding-top: 10px;
    }
}

/* ============================================
   MOBILE OPTIMIZATIONS
   ============================================ */

/* Prevent iOS zoom on input focus - must be 16px minimum */
@media (max-width: 640px) {
    input[type="number"],
    input[type="text"],
    input[type="email"],
    input[type="password"],
    select,
    textarea {
        font-size: 16px;
    }
}

/* Touch target sizes - minimum 44px for accessibility */
@media (max-width: 640px) {
    /* Buttons need larger touch targets */
    .btn {
        min-height: 44px;
        padding: 12px 16px;
    }

    .btn-danger {
        min-width: 44px;
        min-height: 44px;
        padding: 10px;
    }

    .btn-icon {
        min-width: 44px;
        min-height: 44px;
    }

    /* Delete buttons on chips */
    .preset-chip-delete,
    .custom-category-chip button {
        min-width: 28px;
        min-height: 28px;
        font-size: 18px;
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .preset-chip {
        padding: 10px 12px;
        gap: 10px;
    }

    .custom-category-chip {
        padding: 8px 12px;
        gap: 8px;
    }

    /* Toggle buttons */
    .toggle-option {
        min-height: 44px;
        padding: 10px 12px;
    }

    /* Auth and theme buttons */
    .auth-btn {
        min-height: 44px;
        padding: 10px 16px;
    }

    .theme-toggle,
    .help-toggle {
        min-width: 44px;
        min-height: 44px;
    }

    /* Category copy button */
    .category-copy-btn {
        min-width: 40px;
        min-height: 40px;
    }

    /* Copy and adjust buttons */
    .copy-btn,
    .adjust-btn {
        min-height: 36px;
        padding: 8px 12px;
        opacity: 1; /* Always visible on mobile */
    }

    /* Quick split chips */
    .quick-split-chip {
        min-height: 44px;
        padding: 12px 18px;
    }

    /* Split by people button */
    .btn-split-people {
        min-height: 44px;
        padding: 10px 16px;
    }
}

/* Split row layout - improved mobile layout */
@media (max-width: 480px) {
    .split-item {
        display: flex;
        flex-wrap: wrap;
        gap: 10px;
        padding: 16px;
        position: relative;
    }

    /* Category dropdown takes most of the width */
    .split-item select {
        flex: 1;
        min-width: 0;
        order: 1;
    }

    /* Copy button next to dropdown */
    .split-item .category-copy-btn {
        order: 2;
        flex-shrink: 0;
    }

    /* Percentage/amount input and delete on second row */
    .split-item input[type="number"] {
        flex: 1;
        order: 3;
        min-width: 80px;
    }

    /* Delete button */
    .split-item .btn-danger {
        order: 4;
        flex-shrink: 0;
    }
}

/* Card and container padding */
@media (max-width: 480px) {
    body {
        padding: 12px;
    }

    .card {
        padding: 16px;
        border-radius: 12px;
    }

    /* Remainder row adjustments */
    .remainder-row {
        margin: 0 -16px;
        padding: 12px 16px;
    }

    /* Split result section */
    .split-result {
        padding: 20px;
    }
}

/* Typography scaling for mobile */
@media (max-width: 480px) {
    h1 {
        font-size: 1.5rem;
    }

    .subtitle {
        font-size: 0.875rem;
    }

    .splits-header h2,
    .presets-header h3,
    .quick-split-header,
    .custom-categories-header h3 {
        font-size: 0.75rem;
    }

    .result-amount {
        font-size: 1.25rem;
    }

    .total-row .result-amount {
        font-size: 1.5rem;
    }

    .total-row .result-label {
        font-size: 1rem;
    }
}

/* Header and auth area on mobile */
@media (max-width: 480px) {
    .auth-section {
        flex-wrap: wrap;
        gap: 8px;
    }

    .user-info {
        flex-wrap: wrap;
        justify-content: center;
    }

    .user-email {
        max-width: 140px;
        font-size: 0.75rem;
    }

    .sync-indicator {
        font-size: 0.7rem;
        padding: 3px 6px;
    }

    header {
        margin-bottom: 24px;
    }

    .logo {
        width: 48px;
        height: 48px;
        margin-bottom: 12px;
    }

    .logo svg {
        width: 28px;
        height: 28px;
    }
}

/* Quick split section on narrow screens */
@media (max-width: 400px) {
    .quick-split-chips {
        display: grid;
        grid-template-columns: repeat(3, 1fr);
        gap: 8px;
    }

    .quick-split-chip {
        justify-content: center;
        padding: 12px 8px;
        font-size: 0.8rem;
    }

    /* Split by people stacking */
    .split-by-people {
        flex-direction: column;
        align-items: stretch;
        gap: 12px;
    }

    .split-by-people > span,
    .split-by-people > input,
    .split-by-people > button {
        text-align: center;
    }

    .split-by-people input[type="number"] {
        width: 100%;
    }

    .btn-split-people {
        width: 100%;
        justify-content: center;
    }
}

/* Settings row on mobile */
@media (max-width: 400px) {
    .settings-row {
        flex-direction: column;
        gap: 16px;
    }

    .setting-item {
        width: 100%;
    }

    .toggle-group {
        width: 100%;
    }

    .toggle-option {
        flex: 1;
        justify-content: center;
    }
}

/* Button groups on mobile */
@media (max-width: 480px) {
    .btn-group {
        flex-wrap: wrap;
        gap: 8px;
    }

    .splits-header {
        flex-direction: column;
        align-items: stretch;
        gap: 12px;
    }

    .splits-header h2 {
        text-align: center;
    }

    .splits-header .btn-group {
        justify-content: center;
    }
}

/* Modal improvements for mobile */
@media (max-width: 480px) {
    .modal {
        padding: 20px;
        max-height: 90vh;
        margin: 10px;
    }

    .modal h3 {
        font-size: 1.25rem;
    }

    .guide-modal,
    .privacy-modal {
        max-height: 85vh;
    }

    .auth-modal .modal.auth-modal-content {
        max-width: 100%;
        margin: 10px;
    }

    .auth-header {
        padding: 24px 20px;
    }

    .auth-icon {
        width: 56px;
        height: 56px;
    }

    .auth-icon svg {
        width: 28px;
        height: 28px;
    }

    .auth-header h3 {
        font-size: 1.25rem;
    }

    .auth-form {
        padding: 20px;
    }

    .auth-actions {
        padding: 0 20px 24px;
        flex-direction: column;
    }

    .btn-auth-secondary,
    .btn-auth-primary {
        flex: none;
        width: 100%;
    }
}

/* Toast positioning on mobile */
@media (max-width: 480px) {
    .toast {
        left: 12px;
        right: 12px;
        bottom: 12px;
    }
}

/* Hide keyboard hints on mobile (shown on desktop only) */
@media (max-width: 768px) {
    .keyboard-hint {
        display: none !important;
    }
}

/* Ko-fi button adjustment - give it some breathing room */
@media (max-width: 640px) {
    /* Add padding to footer to account for Ko-fi button */
    footer {
        padding-bottom: 80px;
    }
}

/* Safe area insets for notched phones */
@supports (padding: max(0px)) {
    body {
        padding-left: max(12px, env(safe-area-inset-left));
        padding-right: max(12px, env(safe-area-inset-right));
        padding-bottom: max(12px, env(safe-area-inset-bottom));
    }

    @media (max-width: 640px) {
        .toast {
            bottom: max(12px, env(safe-area-inset-bottom));
        }
    }
}