:root {
    --bg: #0b0b0b;
    --panel: #0f1113;
    --muted: #9aa3a8;
    --accent: #00d4ff;
    --danger: #ff6b6b;
    --glass: rgba(255, 255, 255, 0.03);
    --card-shadow: 0 6px 20px rgba(0, 0, 0, 0.6);
    --radius: 12px;
    --text: #e6eef0;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
}

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

html,
body {
    height: 100%;
    background: linear-gradient(180deg, var(--bg), #070707);
    color: var(--text);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    line-height: 1.5;
}

/* MOBILE FIRST APPROACH */
.app {
    padding: 16px;
    min-height: 100vh;
}

.header {
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin-bottom: 20px;
}

.brand {
    display: flex;
    gap: 12px;
    align-items: center;
}

.logo {
    width: 44px;
    height: 44px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent), #00a7e6);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #071018;
    font-weight: 800;
    font-size: 16px;
    flex-shrink: 0;
}

h1 {
    font-size: 18px;
    margin: 0;
}

p.subtitle {
    margin: 4px 0 0 0;
    color: var(--muted);
    font-size: 13px;
    line-height: 1.4;
}

.controls {
    display: flex;
    gap: 8px;
    align-items: center;
    justify-content: space-between;
    width: 100%;
}

.btn {
    background: var(--glass);
    border: 1px solid rgba(255, 255, 255, 0.03);
    padding: 12px 16px;
    border-radius: 10px;
    color: inherit;
    cursor: pointer;
    font-weight: 600;
    font-size: 14px;
    transition: all .2s ease;
    min-height: 44px;
    /* Minimum touch target size */
    flex: 1;
    text-align: center;
}

.btn.primary {
    background: linear-gradient(90deg, var(--accent), #00a7e6);
    color: #071018;
    border: none;
}

.btn.danger {
    background: transparent;
    border: 1px solid var(--danger);
    color: var(--danger);
}

.btn:hover,
.btn:focus {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(0, 212, 255, 0.2);
    outline: none;
}

/* MAIN LAYOUT - MOBILE FIRST */
.grid {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.panel {
    background: rgba(255, 255, 255, 0.02);
    padding: 20px;
    border-radius: 12px;
    transition: all .3s ease;
}

.form-grid {
    display: grid;
    gap: 16px;
}

.row {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

label {
    font-size: 14px;
    color: var(--muted);
    font-weight: 500;
}

input[type="text"],
input[type="number"],
input[type="date"],
select {
    width: 100%;
    padding: 14px;
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    background: rgba(255, 255, 255, 0.05);
    color: inherit;
    font-size: 16px;
    /* Prevents zoom on iOS */
    min-height: 48px;
    transition: all .2s;
}

input[type="text"]:focus,
input[type="number"]:focus,
input[type="date"]:focus,
select:focus {
    border-color: var(--accent);
    outline: none;
    box-shadow: 0 0 0 2px rgba(0, 212, 255, 0.1);
}

.actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-top: 16px;
}

/* FILTERS - MOBILE OPTIMIZED */
.filters-container {
    background: rgba(255, 255, 255, 0.02);
    padding: 16px;
    border-radius: 10px;
    margin-bottom: 16px;
}

.filters-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.filter-full-width {
    grid-column: 1 / -1;
}

.filter-actions {
    grid-column: 1 / -1;
    display: flex;
    gap: 10px;
    margin-top: 8px;
}

/* EXPENSE LIST - MOBILE CARDS INSTEAD OF TABLE */
.expense-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.expense-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 10px;
    padding: 16px;
    animation: fadeIn .4s ease both;
}

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

.expense-meta {
    display: flex;
    flex-direction: column;
    gap: 4px;
    flex: 1;
}

.expense-desc {
    font-weight: 600;
    font-size: 16px;
}

.expense-date {
    color: var(--muted);
    font-size: 13px;
}

.expense-amount {
    font-size: 18px;
    font-weight: 700;
    color: var(--accent);
}

.expense-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.tag {
    display: inline-block;
    padding: 6px 12px;
    border-radius: 999px;
    font-size: 12px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.person-badge {
    font-size: 13px;
    color: var(--muted);
}

.delete-btn {
    background: transparent;
    border: 1px solid var(--danger);
    color: var(--danger);
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all .2s;
}

.summary {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
    margin-top: 20px;
}

.summary-card {
    padding: 16px;
    border-radius: 10px;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.03), transparent);
    text-align: center;
}

.summary-value {
    font-size: 20px;
    font-weight: 700;
    margin-top: 4px;
}

footer {
    margin-top: 30px;
    text-align: center;
    color: var(--muted);
    font-size: 12px;
    padding: 20px 0;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(8px);
    }

    to {
        opacity: 1;
        transform: none;
    }
}

/* TABLET STYLES */
@media (min-width: 768px) {
    .app {
        max-width: 800px;
        margin: 0 auto;
        padding: 24px 20px;
    }

    .header {
        flex-direction: row;
        align-items: center;
        justify-content: space-between;
    }

    .controls {
        width: auto;
        justify-content: flex-end;
    }

    .btn {
        flex: none;
        min-width: 120px;
    }

    .form-grid {
        grid-template-columns: 1fr 1fr;
    }

    .form-full-width {
        grid-column: 1 / -1;
    }

    .filters-grid {
        grid-template-columns: 1fr 1fr 1fr;
    }

    .expense-list {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 16px;
    }
}

/* DESKTOP STYLES */
@media (min-width: 1024px) {
    .app {
        max-width: 1200px;
        padding: 30px;
    }

    .grid {
        display: grid;
        grid-template-columns: 400px 1fr;
        gap: 30px;
        align-items: start;
    }

    .expense-list {
        grid-template-columns: 1fr;
    }

    .filters-grid {
        grid-template-columns: 1fr 1fr 1fr 1fr;
    }

    /* Bring back table for desktop */
    .table-container {
        display: block;
    }

    .expense-list {
        display: none;
    }

    table {
        width: 100%;
        border-collapse: collapse;
        font-size: 14px;
    }

    thead th {
        font-size: 12px;
        color: var(--muted);
        text-align: left;
        padding: 12px 8px;
        border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    }

    tbody td {
        padding: 12px 8px;
        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
        vertical-align: middle;
    }

    tbody tr {
        transition: all .2s;
    }

    tbody tr:hover {
        background: rgba(255, 255, 255, 0.02);
    }
}

/* LARGE DESKTOP */
@media (min-width: 1280px) {
    .expense-list {
        display: none;
    }

    .table-container {
        display: block;
    }
}

/* UTILITY CLASSES */
.hidden-mobile {
    display: none;
}

.visible-mobile {
    display: block;
}

@media (min-width: 1024px) {
    .hidden-mobile {
        display: block;
    }

    .visible-mobile {
        display: none;
    }
}

/* PRINT STYLES */
@media print {
    body {
        background: #fff;
        color: #000;
    }

    .header,
    .controls,
    .filters-container,
    footer,
    .btn,
    .delete-btn {
        display: none !important;
    }

    .panel {
        box-shadow: none;
        background: transparent;
        padding: 0;
    }

    .expense-card {
        break-inside: avoid;
        border: 1px solid #000;
    }
}