/* ==========================================================================
   1. Variables & Design System
   ========================================================================== */
:root {
    /* Color palette */
    --color-primary: #007bff;
    --color-primary-dark: #0056b3;
    --color-secondary: #6c757d;
    --color-success: #28a745;
    --color-info: #17a2b8;
    --color-warning: #ffc107;
    --color-danger: #dc3545;
    --color-light: #f8f9fa;
    --color-dark: #343a40;

    /* Background & Text */
    --bg-color: #f8f9fa;
    --bg-card: #ffffff;
    --bg-body: var(--bg-color);
    --text-main: #2c3e50;
    --text-secondary: #666;
    --text-sub: #6c757d;
    --text-light: #aaa;

    /* Borders & Shadows */
    --border-color: #eaeaea;
    --border-light: #eee;
    --border-focus: var(--color-primary);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 20px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.02);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.08);
    --shadow-xl: 0 10px 30px rgba(0, 0, 0, 0.1);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-family-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-md: 1.1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-xxl: 2rem;
    --font-size-xxxl: 2.5rem;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
}

/* ==========================================================================
   2. Base Reset & Global Styles
   ========================================================================== */
*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-body);
    color: var(--text-main);
    margin: 0;
    padding: var(--spacing-lg);
    min-height: 100vh;
    line-height: 1.5;
}

h1,
h2,
h3,
h4 {
    margin: 0 0 var(--spacing-md) 0;
    line-height: 1.2;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: var(--color-primary-dark);
}

textarea {
    resize: vertical;
}

/* ==========================================================================
   3. Utility Classes
   ========================================================================== */
.flex {
    display: flex;
}

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

.flex-column {
    display: flex;
    flex-direction: column;
}

.flex-between {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.grid {
    display: grid;
    gap: var(--spacing-md);
}

.text-center {
    text-align: center;
}

.w-full {
    width: 100%;
}

.mt-4 {
    margin-top: var(--spacing-lg);
}

.mb-4 {
    margin-bottom: var(--spacing-lg);
}

.hidden {
    display: none;
}

.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
}

/* ==========================================================================
   4. Components (Buttons, Cards, Forms)
   ========================================================================== */
.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    border: none;
    font-weight: var(--font-weight-medium);
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
}

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

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

.btn:disabled {
    background: #ccc;
    cursor: not-allowed;
    opacity: 0.6;
}

.card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}

.form-control {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: border-color 0.2s;
}

.form-control:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.15);
}

.toggle-switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 24px;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 16px;
    width: 16px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

.toggle-switch input:checked+.slider {
    background-color: var(--color-primary);
}

.toggle-switch input:checked+.slider:before {
    transform: translateX(26px);
}

.back-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--text-sub);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-md);
}

/* index.html */
.index-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-md);
}

.nav-card {
    display: flex;
    flex-direction: column;
    height: 100%;
    position: relative;
    overflow: hidden;
    color: inherit;
}

.nav-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-primary);
    box-shadow: var(--shadow-lg);
}

.card-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.card-arrow {
    position: absolute;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    opacity: 0;
    transform: translateX(-10px);
    transition: all 0.3s ease;
    color: var(--color-primary);
}

.nav-card:hover .card-arrow {
    opacity: 1;
    transform: translateX(0);
}

/* time.html */
.time-display {
    font-size: calc(var(--font-size-xxl) * 2);
    font-weight: var(--font-weight-bold);
    margin: var(--spacing-lg) 0;
    font-variant-numeric: tabular-nums;
    letter-spacing: -2px;
    line-height: 1;
    text-align: center;
}

.date-display {
    font-size: var(--font-size-lg);
    color: var(--text-sub);
    margin-bottom: var(--spacing-xxl);
    text-align: center;
}

.offset-info {
    background: rgba(0, 123, 255, 0.05);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: 1px solid rgba(0, 123, 255, 0.1);
}

.offset-value {
    font-size: calc(var(--font-size-lg) * 1.2);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-sm);
}

.offset-value.fast {
    color: var(--color-danger);
}

.offset-value.slow {
    color: #d63384;
}

.offset-value.accurate {
    color: var(--color-success);
}

/* qrcode.html */
.drop-zone {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-xxl) var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
}

.drop-zone:hover,
.drop-zone.dragover {
    border-color: var(--color-primary);
    background-color: rgba(0, 123, 255, 0.05);
}

.preview-img {
    max-width: 100%;
    max-height: 300px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.result-area {
    background-color: var(--bg-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    display: none;
    word-break: break-all;
}

/* uuid.html */
.control-group {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-md);
}

.uuid-output {
    height: 300px;
    width: 100%;
    padding: var(--spacing-md);
    font-family: var(--font-family-mono);
}

/* compress.html */
.range-wrap {
    margin: var(--spacing-lg) 0;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.image-preview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    width: 100%;
    margin-top: var(--spacing-xl);
}

.img-wrapper {
    height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-light);
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-md);
    overflow: hidden;
    border: 1px solid var(--border-light);
}

.img-wrapper img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}