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

:root {
    --tg-safe-area-inset-bottom: env(safe-area-inset-bottom, 0px);
    --accent-color: #6c5ce7;
    --danger-color: #e74c3c;
    --success-color: #27ae60;
    --border-radius: 12px;
    --font-size: 16px;
    --header-height: 56px;
    --nav-height: 64px;
    color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
    :root {
        --tg-theme-bg-color: #0d1117;
        --tg-theme-text-color: #e6edf3;
        --tg-theme-hint-color: #8b949e;
        --tg-theme-secondary-bg-color: #161b22;
    }
}

html, body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: var(--font-size);
    line-height: 1.5;
    background: var(--tg-theme-bg-color, #ffffff);
    color: var(--tg-theme-text-color, #1a1a1a);
    min-height: 100dvh;
    -webkit-font-smoothing: antialiased;
}

#app {
    padding-bottom: calc(var(--nav-height) + 16px);
    min-height: 100dvh;
    transform: translateZ(0);
}

header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--tg-theme-bg-color, #ffffff);
    border-bottom: 1px solid var(--tg-theme-secondary-bg-color, #f0f0f0);
    height: var(--header-height);
    display: flex;
    align-items: center;
}

.header-inner {
    padding: 0 16px;
    width: 100%;
    display: flex;
    align-items: center;
    gap: 8px;
}

header h1 {
    font-size: 20px;
    font-weight: 600;
    flex: 1;
}

.back-btn {
    background: none;
    border: none;
    font-size: 24px;
    color: var(--tg-theme-button-color, #2481cc);
    cursor: pointer;
    padding: 4px 8px;
    line-height: 1;
    -webkit-tap-highlight-color: transparent;
}

.back-btn.hidden {
    display: none;
}

main {
    padding: 16px;
}

.page {
    max-width: 480px;
    margin: 0 auto;
}

/* Bottom Navigation */
#bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 200;
    display: flex;
    background: var(--tg-theme-bg-color, #ffffff);
    border-top: 1px solid var(--tg-theme-secondary-bg-color, #f0f0f0);
    height: var(--nav-height);
    padding-bottom: var(--tg-safe-area-inset-bottom);
}

.nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    color: var(--tg-theme-hint-color, #999999);
    font-size: 11px;
    transition: color 0.2s;
    -webkit-tap-highlight-color: transparent;
}

.nav-item.active {
    color: var(--tg-theme-button-color, #2481cc);
}

.nav-add .nav-icon {
    background: var(--tg-theme-button-color, #2481cc);
    color: var(--tg-theme-button-text-color, #ffffff);
    width: 44px;
    height: 44px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 22px;
    margin-top: -12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.nav-icon {
    font-size: 22px;
    margin-bottom: 2px;
}

.nav-label {
    font-size: 10px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 24px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s, transform 0.1s;
    -webkit-tap-highlight-color: transparent;
    text-decoration: none;
}

.btn:disabled,
.btn.loading {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}

.btn-full {
    width: 100%;
    margin-top: 12px;
}

.btn-primary {
    background: var(--tg-theme-button-color, #2481cc);
    color: var(--tg-theme-button-text-color, #ffffff);
}

.btn-secondary {
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    color: var(--tg-theme-text-color, #1a1a1a);
}

.btn-danger {
    background: var(--danger-color);
    color: #fff;
}

.btn-success {
    background: var(--success-color);
    color: #fff;
}

.btn-floating {
    position: fixed;
    bottom: calc(var(--nav-height) + 16px);
    right: 16px;
    width: auto;
    padding: 16px 24px;
    border-radius: 28px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    z-index: 50;
}

.btn-row {
    display: flex;
    gap: 12px;
    margin-top: 16px;
}

.btn-row .btn {
    flex: 1;
}

/* Forms */
.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    color: var(--tg-theme-hint-color, #999999);
    font-weight: 500;
}

.form-group input:not([type="radio"]):not([type="checkbox"]),
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--tg-theme-secondary-bg-color, #f0f0f0);
    border-radius: var(--border-radius);
    font-size: 16px;
    background: var(--tg-theme-bg-color, #ffffff);
    color: var(--tg-theme-text-color, #1a1a1a);
    outline: none;
    transition: border-color 0.2s;
    -webkit-appearance: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    border-color: var(--tg-theme-button-color, #2481cc);
}

.form-group textarea {
    resize: vertical;
    min-height: 80px;
    font-family: inherit;
}

.radio-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px;
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    border-radius: var(--border-radius);
    cursor: pointer;
}

.radio-label input[type="radio"] {
    width: 20px;
    height: 20px;
    accent-color: var(--tg-theme-button-color, #2481cc);
}

/* Cards / Items */
.item-card {
    display: flex;
    flex-direction: column;
    padding: 16px;
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    border: 2px solid transparent;
    border-radius: var(--border-radius);
    margin-bottom: 10px;
    will-change: transform;
}

.item-card:active {
    opacity: 0.8;
}

.item-card-low {
    border: 2px solid var(--danger-color);
    box-shadow: 0 0 0 1px rgba(231, 76, 60, 0.15);
}

.item-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 8px;
}

.item-card-name {
    font-weight: 600;
    font-size: 17px;
}

.item-card-actions {
    display: flex;
    gap: 8px;
}

.item-card-actions button {
    background: none;
    border: none;
    font-size: 18px;
    cursor: pointer;
    padding: 4px;
    -webkit-tap-highlight-color: transparent;
}

.item-card-details {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 6px;
    font-size: 14px;
    color: var(--tg-theme-hint-color, #999999);
}

.item-card-details span {
    display: flex;
    justify-content: space-between;
}

.item-card-details .label {
    color: var(--tg-theme-hint-color, #999999);
}

.item-card-details .value {
    color: var(--tg-theme-text-color, #1a1a1a);
    font-weight: 500;
}

/* Session cards */
.session-card {
    display: flex;
    align-items: center;
    padding: 0;
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    border-radius: var(--border-radius);
    margin-bottom: 10px;
    will-change: transform;
}

.session-card:active {
    opacity: 0.8;
}

.session-card-inner {
    flex: 1;
    padding: 16px;
    cursor: pointer;
}

.session-card-top {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
}

.session-card-date {
    font-size: 14px;
    color: var(--tg-theme-hint-color, #999999);
}

.session-card-items {
    font-size: 14px;
    color: var(--tg-theme-hint-color, #999999);
}

.session-card-total {
    font-size: 18px;
    font-weight: 700;
    color: var(--accent-color);
}

.session-card-delete {
    background: none;
    border: none;
    font-size: 18px;
    cursor: pointer;
    padding: 16px;
    -webkit-tap-highlight-color: transparent;
}

/* Session items list */
.session-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    border-radius: var(--border-radius);
    margin-bottom: 8px;
}

.session-item-info {
    flex: 1;
}

.session-item-name {
    font-weight: 600;
    font-size: 15px;
}

.session-item-detail {
    font-size: 13px;
    color: var(--tg-theme-hint-color, #999999);
    margin-top: 2px;
}

.session-item-price {
    font-weight: 600;
    font-size: 16px;
    margin-left: 12px;
}

.session-item-remove {
    background: none;
    border: none;
    color: var(--danger-color);
    font-size: 20px;
    cursor: pointer;
    padding: 4px 8px;
}

/* Session totals */
.session-total {
    display: flex;
    justify-content: space-between;
    padding: 12px 0;
    font-size: 16px;
    border-top: 1px solid var(--tg-theme-secondary-bg-color, #f0f0f0);
}

.grand-total {
    font-size: 20px;
    font-weight: 700;
    color: var(--accent-color);
    border-top: 2px solid var(--accent-color);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.5);
    z-index: 300;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    animation: fadeIn 0.2s;
}

.modal.hidden {
    display: none;
}

.modal-content {
    background: var(--tg-theme-bg-color, #ffffff);
    border-radius: 16px 16px 0 0;
    padding: 24px;
    width: 100%;
    max-width: 480px;
    max-height: 80vh;
    overflow-y: auto;
    animation: slideUp 0.3s ease;
}

.modal-close {
    float: right;
    font-size: 28px;
    cursor: pointer;
    color: var(--tg-theme-hint-color, #999999);
    line-height: 1;
}

.modal h2 {
    margin-bottom: 16px;
    font-size: 20px;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { transform: translateY(100%); }
    to { transform: translateY(0); }
}

/* Search */
.search-bar {
    margin-bottom: 16px;
}

.search-bar input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--tg-theme-secondary-bg-color, #f0f0f0);
    border-radius: 24px;
    font-size: 16px;
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    color: var(--tg-theme-text-color, #1a1a1a);
    outline: none;
    transition: border-color 0.2s;
}

.search-bar input:focus {
    border-color: var(--tg-theme-button-color, #2481cc);
    background: var(--tg-theme-bg-color, #ffffff);
}

/* States */
.loading {
    text-align: center;
    padding: 40px;
    color: var(--tg-theme-hint-color, #999999);
}

.empty-state {
    text-align: center;
    padding: 40px 16px;
    color: var(--tg-theme-hint-color, #999999);
    font-size: 16px;
}

.success-message {
    text-align: center;
    padding: 12px;
    background: var(--success-color);
    color: #fff;
    border-radius: var(--border-radius);
    margin-top: 16px;
}

.hidden {
    display: none !important;
}

/* Session detail page */
.session-detail-header {
    margin-bottom: 20px;
}

.session-detail-header h2 {
    font-size: 22px;
    margin-bottom: 4px;
}

.session-detail-header p {
    color: var(--tg-theme-hint-color, #999999);
    font-size: 14px;
}

.session-notes {
    margin-top: 10px;
    padding: 10px 12px;
    background: var(--tg-theme-secondary-bg-color, #f0f0f0);
    border-radius: var(--border-radius);
    font-size: 14px;
    color: var(--tg-theme-text-color, #1a1a1a);
}

.session-card-notes {
    font-size: 13px;
    color: var(--tg-theme-hint-color, #999999);
    margin-bottom: 6px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.session-detail-items {
    margin-bottom: 20px;
}

.session-detail-items h3 {
    margin-bottom: 12px;
    font-size: 16px;
}