/* ============================================
   CSS Reset & Base Styles
   ============================================ */

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

:root {
    /* Colors - Apple-inspired palette */
    --color-primary: #007AFF;
    --color-primary-hover: #0051D5;
    --color-secondary: #5856D6;
    --color-success: #34C759;
    --color-warning: #FF9500;
    --color-danger: #FF3B30;

    --color-bg: #FFFFFF;
    --color-bg-secondary: #F5F5F7;
    --color-bg-tertiary: #E8E8ED;
    --color-surface: #FFFFFF;

    --color-text: #1D1D1F;
    --color-text-secondary: #6E6E73;
    --color-text-tertiary: #86868B;

    --color-border: #D2D2D7;
    --color-border-hover: #A1A1A6;

    /* Typography */
    --font-system: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: "SF Mono", Monaco, "Cascadia Code", "Roboto Mono", Consolas, "Courier New", monospace;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07), 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1), 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1), 0 10px 10px rgba(0, 0, 0, 0.04);

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #000000;
        --color-bg-secondary: #1C1C1E;
        --color-bg-tertiary: #2C2C2E;
        --color-surface: #1C1C1E;

        --color-text: #F5F5F7;
        --color-text-secondary: #A1A1A6;
        --color-text-tertiary: #6E6E73;

        --color-border: #38383A;
        --color-border-hover: #545456;

        --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
        --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4), 0 2px 4px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5), 0 4px 6px rgba(0, 0, 0, 0.3);
        --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.6), 0 10px 10px rgba(0, 0, 0, 0.4);
    }
}

/* ============================================
   Base Typography
   ============================================ */

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

body {
    font-family: var(--font-system);
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ============================================
   Navigation
   ============================================ */

.navbar {
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(20px);
    background-color: rgba(255, 255, 255, 0.8);
}

@media (prefers-color-scheme: dark) {
    .navbar {
        background-color: rgba(28, 28, 30, 0.8);
    }
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    letter-spacing: -0.01em;
}

.nav-logo:hover {
    color: var(--color-primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-sm);
    align-items: center;
}

.nav-item {
    position: relative;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--color-text);
    text-decoration: none;
    font-size: 0.9375rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.nav-link:hover {
    background-color: var(--color-bg-secondary);
    color: var(--color-primary);
}

.nav-link svg {
    transition: transform var(--transition-fast);
}

.nav-dropdown:hover .nav-link svg {
    transform: rotate(180deg);
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    list-style: none;
    padding: var(--spacing-xs);
    margin-top: var(--spacing-xs);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-base);
}

.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu li {
    margin: 0;
}

.dropdown-menu a {
    display: block;
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--color-text);
    text-decoration: none;
    font-size: 0.9375rem;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.dropdown-menu a:hover {
    background-color: var(--color-bg-secondary);
    color: var(--color-primary);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    border-radius: 2px;
    transition: all var(--transition-fast);
}

/* ============================================
   Layout
   ============================================ */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
    flex: 1;
}

/* ============================================
   Header
   ============================================ */

.header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    padding-top: var(--spacing-lg);
}

.title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

.subtitle {
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    color: var(--color-text-secondary);
    font-weight: 400;
}

/* ============================================
   Editor Section
   ============================================ */

.editor-section {
    margin-bottom: var(--spacing-2xl);
}

.toolbar {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    justify-content: flex-end;
}

.text-area {
    width: 100%;
    min-height: 300px;
    padding: var(--spacing-lg);
    font-family: var(--font-system);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-surface);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    resize: vertical;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.text-area:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.1), var(--shadow-md);
}

.text-area::placeholder {
    color: var(--color-text-tertiary);
}

/* ============================================
   Buttons
   ============================================ */

.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    font-family: var(--font-system);
    font-size: 0.9375rem;
    font-weight: 500;
    line-height: 1;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

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

.btn-primary:hover {
    background-color: var(--color-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background-color: var(--color-bg-secondary);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background-color: var(--color-bg-tertiary);
    border-color: var(--color-border-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:active {
    transform: translateY(0);
}

.btn svg {
    width: 16px;
    height: 16px;
}

/* ============================================
   Statistics Section
   ============================================ */

.stats-section {
    margin-bottom: var(--spacing-2xl);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: var(--spacing-lg);
    color: var(--color-text);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: var(--spacing-md);
}

.stat-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-sm);
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-border-hover);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
    font-variant-numeric: tabular-nums;
}

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

/* ============================================
   Details Section
   ============================================ */

.details-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.detail-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.detail-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.detail-grid {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.detail-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);
}

.detail-item:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.detail-label {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
}

.detail-value {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--color-text);
    font-variant-numeric: tabular-nums;
}

.keyword-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    max-height: 300px;
    overflow-y: auto;
}

.keyword-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm);
    background-color: var(--color-bg-secondary);
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
}

.keyword-word {
    font-weight: 500;
    color: var(--color-text);
}

.keyword-count {
    font-weight: 600;
    color: var(--color-primary);
    font-variant-numeric: tabular-nums;
}

.empty-state {
    color: var(--color-text-tertiary);
    font-size: 0.9375rem;
    text-align: center;
    padding: var(--spacing-lg);
}

/* ============================================
   Content Section
   ============================================ */

.content-section {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
    box-shadow: var(--shadow-sm);
}

.content-section h2 {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin-bottom: var(--spacing-lg);
    color: var(--color-text);
}

.content-section h3 {
    font-size: 1.375rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.content-section p {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
}

.content-section ul {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

.content-section li {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
}

.content-section strong {
    font-weight: 600;
    color: var(--color-text);
}

/* ============================================
   Footer
   ============================================ */

.footer {
    background-color: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-xl) var(--spacing-lg);
    margin-top: auto;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer p {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin: 0;
}

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
}

.footer-links a {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--color-primary);
}

/* ============================================
   Scrollbar Styling
   ============================================ */

::-webkit-scrollbar {
    width: 12px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 6px;
    border: 3px solid var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-border-hover);
}

/* ============================================
   Responsive Design
   ============================================ */

@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 60px;
        flex-direction: column;
        background-color: var(--color-surface);
        width: 100%;
        text-align: center;
        transition: left var(--transition-base);
        box-shadow: var(--shadow-lg);
        padding: var(--spacing-lg);
        max-height: calc(100vh - 60px);
        overflow-y: auto;
        gap: 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-item {
        width: 100%;
        margin: var(--spacing-xs) 0;
    }

    .nav-link {
        justify-content: center;
        width: 100%;
    }

    .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        border: none;
        margin-top: var(--spacing-sm);
        background-color: var(--color-bg-secondary);
    }

    .nav-dropdown .dropdown-menu {
        display: none;
    }

    .nav-dropdown.active .dropdown-menu {
        display: block;
    }

    .footer-content {
        flex-direction: column;
        text-align: center;
    }

    .footer-links {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .container {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .header {
        margin-bottom: var(--spacing-xl);
        padding-top: var(--spacing-md);
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-sm);
    }

    .stat-card {
        padding: var(--spacing-md);
    }

    .stat-value {
        font-size: 1.5rem;
    }

    .details-section {
        grid-template-columns: 1fr;
    }

    .content-section {
        padding: var(--spacing-lg);
    }

    .toolbar {
        flex-wrap: wrap;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }

    .text-area {
        min-height: 200px;
        padding: var(--spacing-md);
    }
}

/* ============================================
   Animations
   ============================================ */

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

.stat-card,
.detail-card {
    animation: fadeIn var(--transition-base) ease-out;
}

/* ============================================
   Print Styles
   ============================================ */

@media print {
    body {
        background-color: white;
    }

    .toolbar,
    .footer {
        display: none;
    }

    .text-area {
        border: 1px solid #ccc;
    }

    .stat-card,
    .detail-card,
    .content-section {
        box-shadow: none;
        page-break-inside: avoid;
    }
}

/* ============================================
   Accessibility
   ============================================ */

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

.btn:focus-visible,
.text-area:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* ============================================
   Calculator Section
   ============================================ */

.calculator-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.calculator-card,
.results-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-sm);
}

.input-group {
    margin-bottom: var(--spacing-lg);
}

.input-group label {
    display: block;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
}

.calc-input,
.calc-select {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    font-family: var(--font-system);
    font-size: 1rem;
    color: var(--color-text);
    background-color: var(--color-bg-secondary);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.calc-input:focus,
.calc-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.1);
}

.result-display {
    text-align: center;
    padding: var(--spacing-xl) 0;
    margin-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
}

.result-value {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--color-primary);
    letter-spacing: -0.02em;
    font-variant-numeric: tabular-nums;
}

.result-label {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
    font-weight: 500;
    margin-top: var(--spacing-sm);
}

.result-details {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.detail-row {
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
}

.detail-row:last-child {
    border-bottom: none;
}

.detail-row span:first-child {
    color: var(--color-text-secondary);
    font-size: 0.9375rem;
}

.detail-row span:last-child {
    color: var(--color-text);
    font-weight: 600;
    font-size: 0.9375rem;
}

/* ============================================
   Case Buttons Section
   ============================================ */

.case-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-2xl);
    justify-content: center;
}

.case-buttons .btn {
    flex: 0 1 auto;
}

.stats-info {
    background-color: var(--color-bg-secondary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-2xl);
    text-align: center;
}

.stats-info p {
    margin: 0;
    font-size: 1rem;
    color: var(--color-text-secondary);
}

.stats-info strong {
    color: var(--color-text);
}

.stats-info span {
    color: var(--color-primary);
    font-weight: 600;
}

/* ============================================
   Word Display
   ============================================ */

.results-display {
    margin-bottom: var(--spacing-2xl);
    text-align: center;
}

.word-chips {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    justify-content: center;
    min-height: 120px;
    padding: var(--spacing-lg);
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-md);
}

.word-chip {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    background-color: var(--color-primary);
    color: white;
    border-radius: var(--radius-xl);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    user-select: none;
}

.word-chip:hover {
    background-color: var(--color-primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.word-chip:active {
    transform: translateY(0);
}

/* ============================================
   Tools Grid
   ============================================ */

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.tool-card {
    background-color: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-decoration: none;
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    box-shadow: var(--shadow-sm);
}

.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.tool-icon {
    display: flex;
    align-items: center;
    justify-content: center;
}

.tool-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text);
    margin: 0;
}

.tool-card p {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    margin: 0;
    line-height: 1.6;
}

/* ============================================
   Utilities
   ============================================ */

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}