:root {
    /* Design tokens */
    --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --font-weight-light: 300;
    --font-weight-normal: 400;
    
    /* Colors */
    --color-primary: #34c759;
    --color-background: #ffffff;
    --color-text: #1d1d1f;
    --color-text-secondary: #86868b;
    --color-switch-bg: #e9e9ea;
    --color-shadow: rgba(0, 0, 0, 0.2);
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 2rem;
    --space-lg: 3rem;
    
    /* Transitions */
    --transition-fast: 0.2s;
    --transition-normal: 0.3s;
    
    /* Border radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-full: 9999px;
}

[data-theme="dark"] {
    --color-background: #000000;
    --color-text: #f5f5f7;
    --color-text-secondary: #a1a1a6;
    --color-switch-bg: #38383a;
}

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

html {
    font-size: 16px;
    height: 100%;
}

body {
    font-family: var(--font-primary);
    background-color: var(--color-background);
    color: var(--color-text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transition: background-color var(--transition-normal) ease,
                color var(--transition-normal) ease;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

/* Layout */
.container {
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    padding: var(--space-md);
}

main {
    flex: 1;
    width: 100%;
    display: flex;
    align-items: center;
}

/* Clock styles */
.clock-container {
    margin-bottom: var(--space-md);
    text-align: center;
}

.time {
    font-size: clamp(3.5rem, 10vw, 5rem);
    font-weight: var(--font-weight-light);
    letter-spacing: -0.02em;
    margin-bottom: var(--space-xs);
    line-height: 1.1;
}

.date {
    font-size: clamp(1rem, 3vw, 1.2rem);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-md);
}

/* Controls */
.controls {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    align-items: center;
}

.control-group {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-xs);
}

.switch-label {
    font-size: 0.9rem;
    color: var(--color-text);
    min-width: 120px;
    text-align: right;
}

/* Switch component */
.switch {
    position: relative;
    width: 51px;
    height: 31px;
}

.switch input {
    opacity: 0;
    width: 100%;
    height: 100%;
    position: absolute;
    z-index: 2;
    cursor: pointer;
    margin: 0;
}

.switch input:focus-visible + .slider {
    box-shadow: 0 0 0 2px var(--color-background), 
                0 0 0 4px var(--color-text);
}

.slider {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-switch-bg);
    transition: background-color var(--transition-normal);
    border-radius: var(--radius-full);
    pointer-events: none;
}

.slider:before {
    content: "";
    position: absolute;
    height: 27px;
    width: 27px;
    left: 2px;
    bottom: 2px;
    background-color: var(--color-background);
    transition: transform var(--transition-normal);
    border-radius: 50%;
    box-shadow: 0 2px 4px var(--color-shadow);
    pointer-events: none;
}

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

input:checked + .slider:before {
    transform: translateX(20px);
}

/* Footer */
footer {
    width: 100%;
    text-align: center;
    padding: var(--space-sm);
    background-color: rgba(0, 0, 0, 0.05);
    color: var(--color-text-secondary);
}

footer a {
    color: var(--color-text);
    text-decoration: none;
    padding: 0 var(--space-xs);
}

footer a:hover,
footer a:focus {
    text-decoration: underline;
}

/* About & Privacy Pages */
.about-page,
.privacy-page {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--space-md);
    line-height: 1.6;
    display: block;
    min-height: auto;
    align-items: start;
    justify-content: start;
}

body:has(.about-page),
body:has(.privacy-page) {
    display: block;
    align-items: initial;
    justify-content: initial;
}

.about-page h1,
.privacy-page h1 {
    font-size: 3rem;
    font-weight: var(--font-weight-light);
    margin-bottom: var(--space-lg);
    color: var(--color-text);
    text-align: center;
    letter-spacing: -0.02em;
}

.about-page section,
.privacy-page section {
    background: color-mix(in srgb, var(--color-background) 97%, var(--color-text));
    border-radius: var(--radius-md);
    padding: var(--space-md);
    margin-bottom: var(--space-md);
    box-shadow: 0 2px 4px color-mix(in srgb, var(--color-shadow) 10%, transparent);
    transition: transform var(--transition-normal),
                box-shadow var(--transition-normal);
}

.about-page section:hover,
.privacy-page section:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px color-mix(in srgb, var(--color-shadow) 15%, transparent);
}

.about-page h2,
.privacy-page h2 {
    font-size: 1.75rem;
    font-weight: var(--font-weight-normal);
    margin-bottom: var(--space-md);
    color: var(--color-text);
    border-bottom: 2px solid color-mix(in srgb, var(--color-primary) 15%, transparent);
    padding-bottom: var(--space-xs);
}

.about-page p,
.privacy-page p {
    margin-bottom: var(--space-md);
    font-size: 1.1rem;
    line-height: 1.7;
    color: var(--color-text);
}

.about-page p:last-child,
.privacy-page p:last-child {
    margin-bottom: 0;
}

.about-page ul,
.privacy-page ul {
    list-style: none;
    margin: 0 0 var(--space-md) var(--space-sm);
}

.about-page li,
.privacy-page li {
    margin-bottom: var(--space-sm);
    position: relative;
    padding-left: var(--space-md);
}

.about-page li::before,
.privacy-page li::before {
    content: "•";
    color: var(--color-primary);
    font-weight: bold;
    position: absolute;
    left: 0;
}

.about-page strong,
.privacy-page strong {
    color: var(--color-primary);
    font-weight: 500;
}

.about-page em,
.privacy-page em {
    color: var(--color-text-secondary);
    font-style: normal;
}

/* Navigation buttons */
.page-navigation {
    display: flex;
    justify-content: center;
    gap: var(--space-md);
    margin-top: var(--space-lg);
    padding-top: var(--space-md);
    border-top: 1px solid color-mix(in srgb, var(--color-text) 10%, transparent);
}

.page-navigation a {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-md);
    color: var(--color-text);
    text-decoration: none;
    border-radius: var(--radius-sm);
    background: color-mix(in srgb, var(--color-primary) 10%, transparent);
    transition: background-color var(--transition-normal);
}

.page-navigation a:hover {
    background: color-mix(in srgb, var(--color-primary) 15%, transparent);
}

/* Last updated timestamp */
.privacy-page .last-updated {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    text-align: center;
    margin-top: var(--space-lg);
    padding-top: var(--space-md);
    border-top: 1px solid color-mix(in srgb, var(--color-text) 10%, transparent);
}

/* Media Queries */
@media (prefers-reduced-motion: reduce) {
    * {
        transition: none !important;
        animation: none !important;
    }
}

@media (max-width: 480px) {
    .container {
        padding: var(--space-sm);
    }
    
    .control-group {
        width: 100%;
        justify-content: space-between;
    }
    
    .switch-label {
        text-align: left;
    }
    
    .time {
        font-size: clamp(2.5rem, 8vw, 3.5rem);
    }
}

@media (max-width: 768px) {
    .about-page,
    .privacy-page {
        margin: var(--space-sm);
        padding: var(--space-sm);
    }

    .about-page h1,
    .privacy-page h1 {
        font-size: 2.5rem;
    }

    .about-page h2,
    .privacy-page h2 {
        font-size: 1.5rem;
    }

    .about-page section,
    .privacy-page section {
        padding: var(--space-sm);
    }

    .page-navigation {
        flex-direction: column;
        align-items: stretch;
    }

    .page-navigation a {
        text-align: center;
        justify-content: center;
    }
}

/* Print styles */
@media print {
    .controls {
        display: none;
    }
    
    .time {
        font-size: 24pt;
    }
    
    .date {
        font-size: 14pt;
    }

    .about-page,
    .privacy-page {
        max-width: none;
        padding: 0;
    }

    .about-page section,
    .privacy-page section {
        page-break-inside: avoid;
    }

    .about-page h1,
    .privacy-page h1 {
        font-size: 24pt;
    }

    .about-page h2,
    .privacy-page h2 {
        font-size: 18pt;
    }

    .about-page p,
    .privacy-page p,
    .about-page li,
    .privacy-page li {
        font-size: 12pt;
    }
}