/**
 * Paycheck Frequency Converter - Styles
 *
 * Modern, clean fintech-inspired design
 * Mobile-first responsive approach
 */

/* ============================================
   CSS CUSTOM PROPERTIES (Design Tokens)
   ============================================ */

:root {
    /* Colors - Primary palette */
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-primary-light: #3b82f6;
    --color-primary-bg: #eff6ff;

    /* Colors - Semantic */
    --color-success: #10b981;
    --color-success-bg: #d1fae5;
    --color-warning: #f59e0b;
    --color-warning-bg: #fef3c7;
    --color-error: #ef4444;
    --color-error-bg: #fee2e2;

    /* Colors - Neutrals */
    --color-white: #ffffff;
    --color-gray-50: #f9fafb;
    --color-gray-100: #f3f4f6;
    --color-gray-200: #e5e7eb;
    --color-gray-300: #d1d5db;
    --color-gray-400: #9ca3af;
    --color-gray-500: #6b7280;
    --color-gray-600: #4b5563;
    --color-gray-700: #374151;
    --color-gray-800: #1f2937;
    --color-gray-900: #111827;

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;

    /* Font sizes */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;

    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;

    /* Border radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;

    /* Container */
    --container-max: 960px;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--text-base);
    line-height: 1.6;
    color: var(--color-gray-800);
    background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 50%, #f0fdf4 100%);
    min-height: 100vh;
    padding: var(--space-4);
}

/* ============================================
   LAYOUT
   ============================================ */

.container {
    max-width: var(--container-max);
    margin: 0 auto;
}

/* ============================================
   HEADER
   ============================================ */

.header {
    text-align: center;
    margin-bottom: var(--space-8);
    padding: var(--space-6) 0;
}

.header__title {
    font-size: var(--text-3xl);
    font-weight: 700;
    color: var(--color-gray-900);
    margin-bottom: var(--space-2);
    letter-spacing: -0.025em;
}

.header__subtitle {
    font-size: var(--text-lg);
    color: var(--color-gray-500);
    font-weight: 400;
}

/* ============================================
   CARD COMPONENT
   ============================================ */

.card {
    background: var(--color-white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    padding: var(--space-6);
    margin-bottom: var(--space-6);
}

.card__header {
    margin-bottom: var(--space-5);
    padding-bottom: var(--space-4);
    border-bottom: 1px solid var(--color-gray-100);
}

.card__title {
    font-size: var(--text-lg);
    font-weight: 600;
    color: var(--color-gray-900);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.card__icon {
    font-size: var(--text-xl);
}

/* ============================================
   FORM STYLES
   ============================================ */

.form-grid {
    display: grid;
    gap: var(--space-5);
}

.form-row {
    display: grid;
    gap: var(--space-4);
}

@media (min-width: 640px) {
    .form-row--2col {
        grid-template-columns: repeat(2, 1fr);
    }
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.form-label {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-700);
}

.form-label__hint {
    font-weight: 400;
    color: var(--color-gray-400);
    margin-left: var(--space-1);
}

/* Input styles */
.form-input,
.form-select {
    width: 100%;
    padding: var(--space-3) var(--space-4);
    font-size: var(--text-base);
    font-family: inherit;
    color: var(--color-gray-800);
    background: var(--color-white);
    border: 2px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
    appearance: none;
}

.form-input:hover,
.form-select:hover {
    border-color: var(--color-gray-300);
}

.form-input:focus,
.form-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px var(--color-primary-bg);
}

.form-input.input-error,
.form-select.input-error {
    border-color: var(--color-error);
}

.form-input.input-error:focus,
.form-select.input-error:focus {
    box-shadow: 0 0 0 3px var(--color-error-bg);
}

/* Custom select arrow */
.form-select {
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%236b7280' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right var(--space-3) center;
    background-size: 1.25rem;
    padding-right: var(--space-10);
    cursor: pointer;
}

/* Currency input wrapper */
.input-currency {
    position: relative;
}

.input-currency::before {
    content: '$';
    position: absolute;
    left: var(--space-4);
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-gray-400);
    font-size: var(--text-base);
    font-weight: 500;
    pointer-events: none;
}

.input-currency .form-input {
    padding-left: var(--space-8);
}

/* Field error message */
.field-error {
    font-size: var(--text-xs);
    color: var(--color-error);
    margin-top: calc(var(--space-1) * -1);
}

.hidden {
    display: none !important;
}

/* ============================================
   TOGGLE SWITCH
   ============================================ */

.toggle-group {
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.toggle {
    position: relative;
    width: 52px;
    height: 28px;
}

.toggle__input {
    opacity: 0;
    width: 0;
    height: 0;
    position: absolute;
}

.toggle__slider {
    position: absolute;
    cursor: pointer;
    inset: 0;
    background-color: var(--color-gray-300);
    border-radius: var(--radius-full);
    transition: background-color var(--transition-base);
}

.toggle__slider::before {
    content: '';
    position: absolute;
    height: 22px;
    width: 22px;
    left: 3px;
    bottom: 3px;
    background-color: var(--color-white);
    border-radius: 50%;
    transition: transform var(--transition-base);
    box-shadow: var(--shadow-sm);
}

.toggle__input:checked + .toggle__slider {
    background-color: var(--color-primary);
}

.toggle__input:checked + .toggle__slider::before {
    transform: translateX(24px);
}

.toggle__input:focus + .toggle__slider {
    box-shadow: 0 0 0 3px var(--color-primary-bg);
}

.toggle__label {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-700);
    cursor: pointer;
}

/* ============================================
   OVERTIME SECTION
   ============================================ */

.overtime-section {
    margin-top: var(--space-4);
    padding: var(--space-4);
    background: var(--color-gray-50);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-gray-200);
}

.overtime-section .form-row {
    margin-top: var(--space-3);
}

/* ============================================
   BUTTONS
   ============================================ */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-5);
    font-size: var(--text-sm);
    font-weight: 600;
    font-family: inherit;
    border-radius: var(--radius-lg);
    border: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.btn--secondary {
    background: var(--color-gray-100);
    color: var(--color-gray-700);
}

.btn--secondary:hover {
    background: var(--color-gray-200);
}

.btn--secondary:active,
.btn--secondary.clicked {
    transform: scale(0.97);
}

.form-actions {
    display: flex;
    justify-content: flex-end;
    margin-top: var(--space-4);
    padding-top: var(--space-4);
    border-top: 1px solid var(--color-gray-100);
}

/* ============================================
   ERROR CONTAINER
   ============================================ */

.error-container {
    background: var(--color-error-bg);
    border: 1px solid var(--color-error);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    margin-bottom: var(--space-4);
}

.error-container ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.error-container li {
    color: var(--color-error);
    font-size: var(--text-sm);
    padding: var(--space-1) 0;
}

.error-container li::before {
    content: '• ';
}

/* ============================================
   RESULTS GRID
   ============================================ */

.results-grid {
    display: grid;
    gap: var(--space-4);
    grid-template-columns: 1fr;
}

@media (min-width: 480px) {
    .results-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 768px) {
    .results-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ============================================
   RESULT CARD
   ============================================ */

.result-card {
    background: var(--color-gray-50);
    border: 2px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    text-align: center;
    transition: all var(--transition-base);
}

.result-card.highlight {
    background: var(--color-primary-bg);
    border-color: var(--color-primary);
}

.result-card.highlight .result-label {
    color: var(--color-primary);
}

.result-card.updated {
    animation: pulse 0.3s ease;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.02); }
    100% { transform: scale(1); }
}

.result-label {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-2);
}

.result-value {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--color-gray-900);
    font-family: var(--font-mono);
}

@media (min-width: 640px) {
    .result-value {
        font-size: var(--text-2xl);
    }
}

.result-card.highlight .result-value {
    color: var(--color-primary-dark);
}

/* Span full width for annual card */
.result-card--featured {
    grid-column: 1 / -1;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    border-color: var(--color-primary-dark);
}

.result-card--featured .result-label {
    color: rgba(255, 255, 255, 0.8);
}

.result-card--featured .result-value {
    color: var(--color-white);
    font-size: var(--text-2xl);
}

@media (min-width: 640px) {
    .result-card--featured .result-value {
        font-size: var(--text-3xl);
    }
}

.result-card--featured.highlight {
    background: linear-gradient(135deg, var(--color-success) 0%, #059669 100%);
    border-color: #059669;
}

/* ============================================
   INFO BOXES (Assumptions & Calculations)
   ============================================ */

.info-section {
    display: grid;
    gap: var(--space-4);
    margin-top: var(--space-6);
}

@media (min-width: 640px) {
    .info-section {
        grid-template-columns: repeat(2, 1fr);
    }
}

.info-box {
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
}

.info-box__title {
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--color-gray-700);
    margin-bottom: var(--space-3);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.info-box__title::before {
    content: '';
    display: block;
    width: 4px;
    height: 16px;
    background: var(--color-primary);
    border-radius: 2px;
}

/* Assumptions box */
.assumption-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-2) 0;
    font-size: var(--text-sm);
}

.assumption-item:not(:last-child) {
    border-bottom: 1px solid var(--color-gray-200);
}

.assumption-label {
    color: var(--color-gray-600);
}

.assumption-value {
    font-weight: 600;
    color: var(--color-gray-800);
    font-family: var(--font-mono);
}

.assumption-item.overtime {
    color: var(--color-primary);
}

.assumption-item.overtime .assumption-label {
    color: var(--color-primary);
}

.assumption-divider {
    height: 1px;
    background: var(--color-primary-bg);
    margin: var(--space-2) 0;
}

/* Calculation details */
.calculation-details ol {
    list-style: decimal;
    padding-left: var(--space-5);
    margin: 0;
}

.calculation-details li {
    font-size: var(--text-sm);
    color: var(--color-gray-600);
    padding: var(--space-1) 0;
    line-height: 1.5;
}

/* ============================================
   WARNING BOX
   ============================================ */

.warning-box {
    display: flex;
    align-items: flex-start;
    gap: var(--space-3);
    background: var(--color-warning-bg);
    border: 1px solid var(--color-warning);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    margin-top: var(--space-4);
}

.warning-icon {
    font-size: var(--text-xl);
    flex-shrink: 0;
}

.warning-text {
    font-size: var(--text-sm);
    color: var(--color-gray-700);
    line-height: 1.5;
}

/* ============================================
   ANIMATIONS
   ============================================ */

.fade-in {
    animation: fadeIn 0.3s ease;
}

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

/* ============================================
   FOOTER
   ============================================ */

.footer {
    text-align: center;
    padding: var(--space-6) 0;
    margin-top: var(--space-8);
    color: var(--color-gray-500);
    font-size: var(--text-sm);
}

.footer a {
    color: var(--color-primary);
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

/* ============================================
   ACCESSIBILITY
   ============================================ */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus visible for keyboard navigation */
.form-input:focus-visible,
.form-select:focus-visible,
.btn:focus-visible,
.toggle__input:focus-visible + .toggle__slider {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* ============================================
   PRINT STYLES
   ============================================ */

@media print {
    body {
        background: white;
        padding: 0;
    }

    .card {
        box-shadow: none;
        border: 1px solid var(--color-gray-200);
    }

    .btn {
        display: none;
    }
}