:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --danger: #ef4444;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
}

[hidden] {
    display: none !important;
}

.auth-panel {
    min-height: 100vh;
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(320px, 420px);
    gap: clamp(2rem, 8vw, 8rem);
    align-items: center;
    max-width: 1120px;
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

.auth-copy {
    max-width: 560px;
}

.auth-copy h1 {
    margin: 0.5rem 0 1rem;
    font-size: clamp(2.5rem, 6vw, 5.25rem);
    line-height: 0.98;
    letter-spacing: -0.06em;
}

.auth-copy > p:last-child {
    color: var(--text-muted);
    font-size: 1.125rem;
    max-width: 34rem;
}

.eyebrow {
    color: var(--primary-color);
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.14em;
}

.auth-form {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    box-shadow: 0 20px 50px rgba(15, 23, 42, 0.12);
    display: grid;
    gap: 0.55rem;
    padding: 2rem;
}

.auth-heading {
    margin-bottom: 1rem;
}

.auth-heading span {
    color: var(--text-muted);
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.12em;
}

.auth-heading h2 {
    margin: 0.35rem 0 0;
    font-size: 2rem;
}

.auth-form label {
    color: var(--text-main);
    font-size: 0.875rem;
    font-weight: 600;
    margin-top: 0.5rem;
}

.auth-form .btn-primary {
    margin-top: 1rem;
}

.auth-toggle {
    background: transparent;
    border: 0;
    color: var(--primary-color);
    cursor: pointer;
    font-size: 0.875rem;
    padding: 0.65rem;
}

.auth-error {
    color: var(--danger);
    font-size: 0.8125rem;
    min-height: 1.25rem;
}

.signed-in-user {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

.dashboard {
    max-width: 1000px;
    margin: 2rem auto;
    padding: 0 1rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

header > div:last-child {
    display: flex;
    align-items: center;
    gap: 1rem;
}

h1 {
    font-size: 1.875rem;
    font-weight: 600;
}

.stat-card {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 0.75rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    min-width: 200px;
}

.stat-card .label {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

.stat-card .value {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

main {
    display: grid;
    gap: 2rem;
}

section {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 0.75rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

h2 {
    font-size: 1.25rem;
    margin-bottom: 1.25rem;
    font-weight: 600;
}

#expense-form {
    display: flex;
    gap: 1rem;
}

.form-group {
    flex: 1;
}

input {
    width: 100%;
    padding: 0.625rem 0.875rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 0.875rem;
    transition: border-color 0.2s;
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(79, 70, 229, 0.2);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.625rem 1.25rem;
    border-radius: 0.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}

.btn-primary:hover {
    background: var(--primary-hover);
}

.btn-secondary {
    background: white;
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.875rem;
}

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

.list-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.table-responsive {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

th {
    padding: 0.75rem;
    border-bottom: 2px solid var(--border-color);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-muted);
}

td {
    padding: 1rem 0.75rem;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.875rem;
}

.amount {
    font-weight: 600;
}

.delete-btn {
    color: var(--danger);
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.875rem;
}

.mobile-cards {
    display: none;
}

@media (max-width: 640px) {
    .auth-panel {
        grid-template-columns: 1fr;
        gap: 2rem;
        padding: 2rem 1rem;
    }

    .auth-copy h1 {
        font-size: 3rem;
    }

    .auth-form {
        padding: 1.25rem;
    }

    .dashboard {
        margin: 1rem auto;
        padding: 0 0.5rem;
    }

    header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
        margin-bottom: 1rem;
    }

    header > div:last-child {
        align-items: stretch;
        flex-direction: column;
        width: 100%;
    }

    h1 {
        font-size: 1.5rem;
    }

    .stat-card {
        min-width: unset;
        width: 100%;
        padding: 1rem;
    }

    .stat-card .value {
        font-size: 1.25rem;
    }

    section {
        padding: 1rem;
    }

    h2 {
        font-size: 1.125rem;
        margin-bottom: 1rem;
    }

    .list-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .list-header > div {
        display: flex;
        gap: 0.5rem;
        width: 100%;
    }

    .btn-secondary {
        flex: 1;
        padding: 0.75rem;
        font-size: 0.875rem;
    }

    /* Mobile table as cards */
    .table-responsive {
        overflow-x: visible;
    }

    table {
        display: none;
    }

    .mobile-cards {
        display: block;
    }

    .mobile-cards .card {
        background: var(--card-bg);
        border: 1px solid var(--border-color);
        border-radius: 0.5rem;
        padding: 1rem;
        margin-bottom: 1rem;
        box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    }

    .mobile-cards .card-row {
        display: flex;
        justify-content: space-between;
        margin-bottom: 0.5rem;
    }

    .mobile-cards .card-row:last-child {
        margin-bottom: 0;
    }

    .mobile-cards .label {
        font-weight: 500;
        color: var(--text-muted);
    }

    .mobile-cards .value {
        font-weight: 600;
    }

    .mobile-cards .amount {
        color: inherit;
    }
}