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

:root {
    --primary-color: #4a90e2;
    --primary-dark: #357abd;
    --accent-color: #50e3c2;
    --bg-gradient-start: #f5f7fa;
    --bg-gradient-end: #c3cfe2;
    --text-color: #333;
    --text-muted: #6c757d;
    --white: #ffffff;
    --light-gray: #f8f9fa;
    --border-color: #e9ecef;
    --shadow-soft: 0 10px 30px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 15px 35px rgba(0, 0, 0, 0.1);
    --radius-lg: 16px;
    --radius-md: 12px;
    --radius-sm: 8px;
    --radius-pill: 50px;
}

body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}

.calculator-container {
    background-color: var(--white);
    padding: 40px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-soft);
    width: 100%;
    max-width: 700px;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

h1 {
    color: var(--primary-dark);
    margin-bottom: 25px;
    font-weight: 700;
    font-size: 2rem;
    letter-spacing: -0.5px;
}

/* Modern Segmented Control / Pill Tabs */
.tabs {
    display: flex;
    justify-content: flex-start;
    gap: 10px;
    margin-bottom: 35px;
    overflow-x: auto;
    padding-bottom: 10px; /* Space for scrollbar if needed */
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none; /* Firefox */
}

.tabs::-webkit-scrollbar {
    display: none; /* Chrome, Safari, Opera */
}

.tab-button {
    background-color: var(--light-gray);
    border: 1px solid var(--border-color);
    padding: 10px 20px;
    border-radius: var(--radius-pill);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-muted);
    transition: all 0.2s ease;
    white-space: nowrap;
    text-decoration: none;
    display: inline-block;
}

.tab-button:hover {
    background-color: #e2e6ea;
    color: var(--primary-dark);
    transform: translateY(-1px);
}

.tab-button.active {
    background-color: var(--primary-color);
    color: var(--white);
    border-color: var(--primary-color);
    box-shadow: 0 4px 10px rgba(74, 144, 226, 0.3);
}

.tab-button:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.3);
}

/* Calculator Sections */
.calculator-section {
    display: none;
    animation: fadeIn 0.4s ease-out;
}

.calculator-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

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

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-color);
    font-size: 0.95rem;
}

input[type="number"],
input[type="text"],
select {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
    font-size: 1rem;
    background-color: var(--light-gray);
    transition: all 0.3s ease;
    color: var(--text-color);
}

input:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    background-color: var(--white);
    box-shadow: 0 0 0 4px rgba(74, 144, 226, 0.1);
}

/* Buttons */
button[type="submit"] {
    width: 100%;
    padding: 16px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: 600;
    transition: all 0.3s ease;
    margin-top: 15px;
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
}

button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(74, 144, 226, 0.4);
}

button[type="submit"]:active {
    transform: translateY(0);
}

/* Results */
.result-container {
    margin-top: 35px;
    padding: 25px;
    background-color: #f0f7ff; /* Very light blue */
    border-radius: var(--radius-md);
    border: 1px solid #d0e1f5;
}

.result-container h2 {
    margin: 0;
    color: var(--primary-dark);
    font-size: 1.6rem;
    font-weight: 700;
}

#total-amount, #hourly-rate-amount, #grand-total, #date-range-total {
    display: block;
    margin-top: 5px;
    font-size: 2rem;
    color: var(--primary-color);
}

.assumptions {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 20px;
    text-align: center;
    font-style: italic;
}

.detailed-result {
    padding: 25px;
    text-align: left;
}

.detailed-result p {
    margin: 0 0 15px 0;
    font-size: 1rem;
    color: var(--text-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #e1e8ed;
    padding-bottom: 10px;
}

.detailed-result p:last-child {
    border-bottom: none;
}

.detailed-result p span {
    font-weight: 700;
    color: var(--primary-dark);
}

.detailed-result h2 {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 2px solid var(--primary-color);
    font-size: 1.6rem;
    color: var(--primary-dark);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Flatpickr Theme overrides */
.flatpickr-calendar {
    box-shadow: var(--shadow-hover) !important;
    border-radius: var(--radius-md) !important;
    border: none !important;
}

.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(--primary-color) !important;
    border-color: var(--primary-color) !important;
}

/* Responsive */
@media (min-width: 768px) {
    #invoice-form, #hourly-rate-form, #adjustment-form, #date-range-form {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 25px;
        align-items: start;
    }

    button[type="submit"] {
        grid-column: 1 / -1; 
        width: auto; 
        min-width: 250px;
        margin: 20px auto 0;
    }
    
    .tabs {
        justify-content: center;
        flex-wrap: wrap;
        overflow: visible;
    }
}