@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

/* ===== Design Tokens ===== */
:root {
    --color-bg-page: #f8fafc;
    --color-bg-card: #ffffff;
    --color-accent: #2563eb;
    --color-accent-hover: #1d4ed8;
    --color-text-primary: #1e293b;
    --color-text-secondary: #64748b;
    --color-border: #e2e8f0;
    --color-input-bg: #ffffff;
    --color-input-focus-bg: #f8fafc;
    --color-result-bg: #f1f5f9;
    --color-shadow: rgba(0, 0, 0, 0.05);
    --color-shadow-hover: rgba(0, 0, 0, 0.1);
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
}

[data-theme="dark"] {
    --color-bg-page: #0f172a;
    --color-bg-card: #1e293b;
    --color-accent: #3b82f6;
    --color-accent-hover: #2563eb;
    --color-text-primary: #f1f5f9;
    --color-text-secondary: #94a3b8;
    --color-border: #334155;
    --color-input-bg: #0f172a;
    --color-input-focus-bg: #1e293b;
    --color-result-bg: #0f172a;
    --color-shadow: rgba(0, 0, 0, 0.3);
    --color-shadow-hover: rgba(0, 0, 0, 0.5);
}

/* ===== Base ===== */
body {
    font-family: var(--font-family);
    background-color: var(--color-bg-page);
    color: var(--color-text-primary);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    margin: 0;
    padding: 24px 16px;
    transition: background-color 0.3s, color 0.3s;
}

.calculator-container {
    background-color: var(--color-bg-card);
    padding: 32px;
    border-radius: var(--radius-lg);
    box-shadow: 0 1px 3px var(--color-shadow);
    width: 100%;
    max-width: 450px;
    text-align: center;
    transition: background-color 0.3s, box-shadow 0.3s;
}

h1 {
    color: var(--color-text-primary);
    margin-bottom: 24px;
    font-weight: 700;
    font-size: 1.75rem;
}

h2 {
    color: var(--color-text-primary);
}

/* ===== Forms ===== */
.form-group {
    margin-bottom: 20px;
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
    color: var(--color-text-secondary);
    font-size: 0.875rem;
}

input[type="number"],
input[type="text"],
input[type="email"],
input[type="tel"],
select,
textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    box-sizing: border-box;
    font-family: var(--font-family);
    font-size: 0.9375rem;
    color: var(--color-text-primary);
    background-color: var(--color-input-bg);
    transition: border-color 0.2s, background-color 0.2s, box-shadow 0.2s;
}

input[type="number"]:focus,
input[type="text"]:focus,
input[type="email"]:focus,
input[type="tel"]:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--color-accent);
    background-color: var(--color-input-focus-bg);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

[data-theme="dark"] input[type="number"]:focus,
[data-theme="dark"] input[type="text"]:focus,
[data-theme="dark"] input[type="email"]:focus,
[data-theme="dark"] input[type="tel"]:focus,
[data-theme="dark"] select:focus,
[data-theme="dark"] textarea:focus {
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

/* ===== Buttons ===== */
button {
    width: 100%;
    padding: 12px 20px;
    background-color: var(--color-accent);
    color: #ffffff;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-family: var(--font-family);
    font-size: 1rem;
    font-weight: 600;
    transition: background-color 0.2s;
    margin-top: 10px;
}

button:hover {
    background-color: var(--color-accent-hover);
}

/* ===== Results ===== */
.result-container {
    margin-top: 24px;
    padding: 16px 20px;
    background-color: transparent;
    border-left: 4px solid var(--color-accent);
    border-radius: 0;
}

.result-container h2 {
    margin: 0;
    color: var(--color-text-primary);
    font-size: 1.25rem;
    font-weight: 600;
}

#total-amount {
    font-weight: 600;
}

.sub-heading {
    font-size: 1.5rem;
    color: var(--color-text-primary);
    font-weight: 700;
}

.assumptions {
    font-size: 0.8rem;
    color: var(--color-text-secondary);
    margin-top: 12px;
    text-align: center;
}

.detailed-result {
    padding: 20px;
    text-align: left;
}

.detailed-result p {
    margin: 0 0 10px 0;
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
}

.detailed-result p span {
    font-weight: 600;
    color: var(--color-text-primary);
    float: right;
}

.detailed-result h2 {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--color-border);
    font-size: 1.25rem;
    color: var(--color-text-primary);
}

.detailed-result h2 span {
    float: right;
}

/* ===== Date Inputs ===== */
#start-date, #end-date {
    cursor: pointer;
    background-color: var(--color-input-bg);
}

/* ===== Flatpickr Theme ===== */
.flatpickr-day.selected,
.flatpickr-day.startRange,
.flatpickr-day.endRange,
.flatpickr-day.selected.inRange,
.flatpickr-day.startRange.inRange,
.flatpickr-day.endRange.inRange,
.flatpickr-day.selected:focus,
.flatpickr-day.startRange:focus,
.flatpickr-day.endRange:focus,
.flatpickr-day.selected:hover,
.flatpickr-day.startRange:hover,
.flatpickr-day.endRange:hover,
.flatpickr-day.selected.prevMonthDay,
.flatpickr-day.startRange.prevMonthDay,
.flatpickr-day.endRange.prevMonthDay,
.flatpickr-day.selected.nextMonthDay,
.flatpickr-day.startRange.nextMonthDay,
.flatpickr-day.endRange.nextMonthDay {
    background: var(--color-accent);
    border-color: var(--color-accent);
}

.flatpickr-day.today {
    border-color: var(--color-accent);
}

.flatpickr-day.today:hover {
    background: rgba(37, 99, 235, 0.1);
    border-color: var(--color-accent);
}

/* Flatpickr Dark Mode */
[data-theme="dark"] .flatpickr-calendar {
    background: var(--color-bg-card);
    border-color: var(--color-border);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .flatpickr-day {
    color: var(--color-text-primary);
}

[data-theme="dark"] .flatpickr-day:hover {
    background: var(--color-border);
    border-color: var(--color-border);
}

[data-theme="dark"] .flatpickr-day.prevMonthDay,
[data-theme="dark"] .flatpickr-day.nextMonthDay {
    color: var(--color-text-secondary);
}

[data-theme="dark"] .flatpickr-months .flatpickr-month,
[data-theme="dark"] .flatpickr-current-month .flatpickr-monthDropdown-months,
[data-theme="dark"] .flatpickr-weekdays,
[data-theme="dark"] span.flatpickr-weekday {
    background: var(--color-bg-card);
    color: var(--color-text-secondary);
}

[data-theme="dark"] .flatpickr-current-month input.cur-year {
    color: var(--color-text-primary);
}

[data-theme="dark"] .flatpickr-months .flatpickr-prev-month,
[data-theme="dark"] .flatpickr-months .flatpickr-next-month {
    fill: var(--color-text-secondary);
}

[data-theme="dark"] .flatpickr-months .flatpickr-prev-month svg,
[data-theme="dark"] .flatpickr-months .flatpickr-next-month svg {
    fill: var(--color-text-secondary);
}

/* ===== Site Header ===== */
.site-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--color-border);
    gap: 12px;
}

.site-header h1 {
    margin-bottom: 0;
    font-size: 1.25rem;
}

.site-header h1 a {
    text-decoration: none;
    color: inherit;
}

/* Page nav links */
.page-nav {
    display: flex;
    gap: 4px;
}

.page-nav a {
    text-decoration: none;
    color: var(--color-text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    transition: color 0.2s, background-color 0.2s;
}

.page-nav a:hover,
.page-nav a.active {
    color: var(--color-accent);
    background-color: rgba(37, 99, 235, 0.08);
}

[data-theme="dark"] .page-nav a:hover,
[data-theme="dark"] .page-nav a.active {
    background-color: rgba(59, 130, 246, 0.12);
}

/* Dark mode toggle */
.theme-toggle {
    background: none;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 6px 10px;
    cursor: pointer;
    color: var(--color-text-secondary);
    font-size: 1.1rem;
    width: auto;
    margin-top: 0;
    transition: border-color 0.2s, color 0.2s;
    line-height: 1;
}

.theme-toggle:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
    background-color: transparent;
}

/* ===== Tab Bar ===== */
.tab-bar {
    display: flex;
    gap: 0;
    border-bottom: 2px solid var(--color-border);
    margin-bottom: 28px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
}

.tab-bar::-webkit-scrollbar {
    display: none;
}

.tab-bar button {
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    margin-bottom: -2px;
    padding: 10px 16px;
    font-family: var(--font-family);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    cursor: pointer;
    white-space: nowrap;
    transition: color 0.2s, border-color 0.2s;
    width: auto;
    margin-top: 0;
    border-radius: 0;
}

.tab-bar button:hover {
    color: var(--color-text-primary);
    background-color: transparent;
}

.tab-bar button.active {
    color: var(--color-accent);
    border-bottom-color: var(--color-accent);
    font-weight: 600;
    background-color: transparent;
}

/* Tab content visibility */
.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* ===== Desktop ===== */
@media (min-width: 768px) {
    .calculator-container {
        max-width: 680px;
        padding: 40px;
    }

    #invoice-form,
    #hourly-rate-form,
    #adjustment-form,
    #date-range-form {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 16px;
        align-items: start;
    }

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

    #invoice-form button,
    #hourly-rate-form button,
    #adjustment-form button,
    #date-range-form button {
        grid-column: 1 / -1;
        width: auto;
        max-width: 200px;
        margin: 8px auto 0;
    }

    h1 {
        font-size: 1.75rem;
    }

    .sub-heading {
        font-size: 1.5rem;
    }

    .site-header h1 {
        font-size: 1.375rem;
    }
}

/* ===== Hero Section ===== */
.hero-section {
    margin-bottom: 20px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--color-border);
}

.hero-tagline {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    line-height: 1.6;
    margin: 0;
    text-align: center;
}

/* ===== Site Footer ===== */
.site-footer {
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid var(--color-border);
    text-align: left;
}

.footer-links {
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
    margin-bottom: 16px;
}

.footer-col h3 {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-secondary);
    margin: 0 0 8px;
}

.footer-col ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.footer-col ul li a {
    font-size: 0.8125rem;
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color 0.2s;
}

.footer-col ul li a:hover {
    color: var(--color-accent);
}

.footer-copy {
    font-size: 0.75rem;
    color: var(--color-text-secondary);
    margin: 0;
    opacity: 0.7;
}