/* === VARIABLES === */
:root {
    --bg-primary: #050505;
    --bg-secondary: #121212;
    --bg-card: #1e1e1e;
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --accent: #ff6b35;
    --accent-glow: rgba(255, 107, 53, 0.3);
    --success: #00e676;
    --warning: #ffea00;
    --error: #ff1744;
    --border: #333;
    --radius-lg: 1rem;
    --radius-sm: 0.5rem;
    --nav-height: 65px;
    --safe-area-bottom: env(safe-area-inset-bottom);
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

    /* Responsive spacing system */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --content-padding-bottom: 5rem;

    /* Responsive typography */
    --font-xs: 0.875rem;
    --font-sm: 0.9375rem;
    --font-base: 1rem;
    --font-lg: 1.125rem;
}

/* === ACCESSIBILITY === */

/* Skip to main content link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--accent);
    color: white;
    padding: 8px 16px;
    text-decoration: none;
    border-radius: 0 0 var(--radius-sm) 0;
    z-index: 10000;
    font-weight: 600;
}

.skip-link:focus {
    top: 0;
    outline: 2px solid var(--success);
    outline-offset: 2px;
}

/* Screen reader only text */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

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

body.reduce-motion *,
body.reduce-motion *::before,
body.reduce-motion *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --border: #ffffff;
        --text-secondary: #ffffff;
    }
}

/* === CORE === */
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

/* Allow text selection for accessibility - only disable on interactive elements */
/* Sentinel: Law of Universality - Prevent double-tap zoom on all interactive elements */
button, .nav-item, .stepper-btn, .set-btn, .timer-dock, summary, label, a, input, select, textarea, [role="button"], [role="tab"], [role="switch"] { touch-action: manipulation; }
button, .nav-item, .stepper-btn, .set-btn, summary, label { user-select: none; }

body {
    background: var(--bg-primary); color: var(--text-primary);
    font-family: var(--font-sans); margin: 0;
    height: 100vh; /* Fallback */
    height: 100dvh; /* Dynamic viewport height for mobile browsers */
    display: flex; flex-direction: column; overflow: hidden;
    font-size: var(--font-base);
}

/* Keyboard focus outline for accessibility (enhanced) */
*:focus {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

*:focus:not(:focus-visible) {
    outline: none;
}

*:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

/* === LAYOUT === */
#app { height: 100%; display: flex; flex-direction: column; }
#main-content {
    flex: 1; overflow-y: auto; overflow-x: hidden;
    padding: var(--spacing-md) var(--spacing-md) calc(var(--nav-height) + var(--content-padding-bottom)) var(--spacing-md);
    scroll-behavior: smooth;
}
.container { max-width: 600px; margin: 0 auto; width: 100%; padding: 0 var(--spacing-xs); }
.flex-row { display: flex; align-items: center; }

/* === TYPOGRAPHY === */
h1 { font-size: 1.75rem; font-weight: 800; letter-spacing: -0.5px; margin: 0 0 var(--spacing-sm) 0; }
h2 { font-size: 1.4rem; font-weight: 700; margin-bottom: var(--spacing-md); color: var(--text-primary); }
h3 { font-size: 1.1rem; font-weight: 600; color: var(--text-primary); margin-bottom: var(--spacing-sm); }
.text-xs { font-size: var(--font-xs); color: var(--text-secondary); letter-spacing: 0.5px; }
a { transition: all 0.2s ease; }
a:active { transform: scale(0.9); opacity: 0.7; }
summary { cursor: pointer; transition: all 0.2s ease; }
summary:active { transform: scale(0.98); opacity: 0.8; }

/* === CARDS === */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
    transition: transform 0.2s;
}
.card:active { transform: scale(0.995); }

/* === CONTROLS === */
.stepper-control {
    display: flex; align-items: center; gap: var(--spacing-sm);
    background: var(--bg-secondary); padding: var(--spacing-xs);
    border-radius: var(--radius-sm); border: 1px solid var(--border);
}
.stepper-btn {
    width: 44px; height: 44px; border-radius: var(--radius-sm);
    border: 2px solid var(--accent); background: var(--bg-card); color: var(--accent);
    font-size: 1.5rem; font-weight: bold; cursor: pointer;
    display: flex; align-items: center; justify-content: center;
    transition: all 0.2s ease;
    flex-shrink: 0;
}
.stepper-btn:active {
    transform: scale(0.92);
    background: var(--accent);
    color: var(--bg-primary);
    box-shadow: 0 0 12px var(--accent-glow);
}
.stepper-btn:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}
.stepper-value {
    flex: 1; text-align: center; font-size: 1.5rem; font-weight: 700;
    font-variant-numeric: tabular-nums; background: transparent; border: none; color: white;
    min-width: 0; max-width: 100%;
}
.set-group { display: flex; gap: var(--spacing-sm); margin-top: var(--spacing-md); }
.set-btn {
    flex: 1; height: 48px; border-radius: var(--radius-sm);
    border: 1px solid var(--border); background: var(--bg-secondary);
    color: var(--text-secondary); font-weight: 600;
    display: flex; align-items: center; justify-content: center;
    transition: all 0.2s ease; cursor: pointer;
}
.set-btn:active {
    transform: scale(0.95);
    background: var(--bg-card);
}
.set-btn.completed {
    background: var(--success); color: #000; border-color: var(--success);
    box-shadow: 0 0 10px rgba(0, 230, 118, 0.3);
}
.set-btn.completed:active {
    transform: scale(0.95);
    box-shadow: 0 0 20px rgba(0, 230, 118, 0.5);
}

/* === BUTTONS === */
.btn-primary {
    background: var(--accent); color: white; border: none;
    width: 100%; padding: var(--spacing-md); border-radius: var(--radius-lg);
    font-size: var(--font-base); font-weight: 700; text-transform: uppercase; letter-spacing: 1px;
    box-shadow: 0 4px 15px var(--accent-glow); margin-top: var(--spacing-md);
    transition: all 0.2s ease; cursor: pointer;
}
.btn-primary:active {
    transform: scale(0.98);
    box-shadow: 0 2px 8px var(--accent-glow);
}
.btn-secondary {
    background: var(--bg-secondary); color: var(--text-secondary);
    width: 100%; padding: var(--spacing-md); border-radius: var(--radius-sm);
    border: 1px solid var(--border); font-weight: 600; cursor: pointer;
    transition: all 0.2s ease;
}
.btn-secondary:active {
    transform: scale(0.98);
    background: var(--bg-card);
}

/* === TIMER DOCK === */
.timer-dock {
    position: fixed; bottom: calc(var(--nav-height) + var(--spacing-sm));
    left: 50%; transform: translateX(-50%) translateY(150%);
    width: 95%; max-width: 580px;
    background: rgba(30, 30, 30, 0.95); backdrop-filter: blur(10px);
    border: 1px solid var(--accent); border-radius: 50px;
    padding: var(--spacing-md) var(--spacing-lg);
    display: flex; justify-content: space-between; align-items: center;
    z-index: 500; transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
}
.timer-dock.active { transform: translateX(-50%) translateY(0); }
.timer-display { font-size: 1.5rem; font-weight: 900; color: var(--accent); font-variant-numeric: tabular-nums; }
.timer-skip { color: var(--text-secondary); font-size: var(--font-sm); letter-spacing: 1px; cursor: pointer; transition: all 0.2s ease; }
.timer-skip:active { transform: scale(0.95); color: var(--accent); }

/* === NAVIGATION === */
.bottom-nav {
    height: var(--nav-height); background: rgba(5, 5, 5, 0.95);
    backdrop-filter: blur(10px); border-top: 1px solid var(--border);
    display: flex; justify-content: space-around; align-items: center;
    position: fixed; bottom: 0; width: 100%; z-index: 1000;
    padding-bottom: var(--safe-area-bottom);
}
.nav-item {
    background: none; border: none; color: var(--text-secondary);
    display: flex; flex-direction: column; align-items: center; gap: var(--spacing-xs);
    font-size: var(--font-xs); font-weight: 600; opacity: 0.6; transition: 0.2s;
    cursor: pointer; padding: var(--spacing-sm);
}
.nav-item:active { transform: scale(0.92); }
.nav-item.active { opacity: 1; color: var(--accent); transform: translateY(-2px); }
.nav-item.active:active { transform: translateY(-2px) scale(0.92); }
.nav-item .icon { font-size: 1.4rem; }

/* === MODALS === */
.modal-overlay {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(0, 0, 0, 0.85); backdrop-filter: blur(8px);
    z-index: 2000; display: flex; align-items: center; justify-content: center;
    opacity: 0; visibility: hidden; transition: 0.2s ease;
    padding: var(--spacing-md);
}
.modal-overlay.active { opacity: 1; visibility: visible; }
.modal-box {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius-lg); padding: var(--spacing-lg);
    width: 100%; max-width: 400px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.5);
    transform: scale(0.95) translateY(var(--spacing-sm)); transition: 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}
.modal-overlay.active .modal-box { transform: scale(1) translateY(0); }
.modal-actions { display: flex; gap: var(--spacing-md); justify-content: flex-end; margin-top: var(--spacing-lg); }
.btn-modal { padding: var(--spacing-md) var(--spacing-lg); border-radius: var(--radius-sm); font-weight: 600; border: none; cursor: pointer; transition: all 0.2s ease; }
.btn-modal:active { transform: scale(0.96); }
.btn-confirm { background: var(--accent); color: white; }
.btn-danger { background: var(--error); color: white; }
.btn-ghost { background: transparent; color: var(--text-secondary); }

/* === UTILS === */
.hidden { display: none !important; }
.fade-in { animation: fadeIn 0.4s ease-out; }
.big-check { width: 1.5rem; height: 1.5rem; accent-color: var(--accent); margin-right: var(--spacing-md); }
.checkbox-wrapper { display: flex; align-items: center; padding: var(--spacing-md); background: var(--bg-secondary); border-radius: var(--radius-sm); margin-bottom: var(--spacing-sm); }
@keyframes fadeIn { from { opacity: 0; transform: translateY(var(--spacing-sm)); } to { opacity: 1; transform: translateY(0); } }

/* === RESPONSIVE MEDIA QUERIES === */

/* Small mobile devices (< 375px) */
@media (max-width: 374px) {
    :root {
        --spacing-md: 0.75rem;
        --spacing-lg: 1rem;
        --content-padding-bottom: 4rem;
        --font-xs: 0.8125rem;
    }

    h1 { font-size: 1.5rem; }
    h2 { font-size: 1.25rem; }

    .card { padding: var(--spacing-md); }
    .stepper-btn { width: 40px; height: 40px; font-size: 1.25rem; }
    .timer-dock { padding: var(--spacing-sm) var(--spacing-md); }
    .timer-display { font-size: 1.25rem; }
    .nav-item .icon { font-size: 1.25rem; }
}

/* Mobile devices (375px - 767px) - Default styles already optimized */
@media (min-width: 375px) and (max-width: 767px) {
    :root {
        --content-padding-bottom: 5rem;
    }
}

/* Tablet devices (768px - 1023px) */
@media (min-width: 768px) {
    :root {
        --spacing-md: 1.25rem;
        --spacing-lg: 2rem;
        --spacing-xl: 2.5rem;
        --content-padding-bottom: 4rem;
        --font-base: 1.0625rem;
        --font-lg: 1.25rem;
    }

    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.25rem; }

    .container { max-width: 700px; }
    .card { padding: var(--spacing-xl); }

    #main-content {
        padding: var(--spacing-lg) var(--spacing-md) calc(var(--nav-height) + var(--content-padding-bottom)) var(--spacing-md);
    }

    .stepper-btn { width: 48px; height: 48px; }
    .set-btn { height: 52px; font-size: var(--font-lg); }

    .btn-primary { font-size: var(--font-lg); padding: 1.125rem; }

    .modal-box { max-width: 500px; padding: var(--spacing-xl); }
    .timer-dock { max-width: 650px; }
}

/* Desktop devices (1024px - 1439px) */
@media (min-width: 1024px) {
    :root {
        --spacing-md: 1.5rem;
        --spacing-lg: 2.5rem;
        --spacing-xl: 3rem;
        --content-padding-bottom: 3rem;
        --font-base: 1.125rem;
        --font-lg: 1.375rem;
    }

    h1 { font-size: 2.25rem; }
    h2 { font-size: 1.75rem; }

    .container { max-width: 800px; }

    #main-content {
        padding: var(--spacing-xl) var(--spacing-lg) calc(var(--nav-height) + var(--content-padding-bottom)) var(--spacing-lg);
    }

    .modal-box { max-width: 550px; }
    .timer-dock { max-width: 700px; }

    /* Hover states for desktop */
    .stepper-btn:hover:not(:active) {
        background: var(--accent);
        color: var(--bg-primary);
        box-shadow: 0 0 8px var(--accent-glow);
    }

    .set-btn:hover:not(:active) {
        background: var(--bg-card);
        border-color: var(--accent);
    }

    .btn-primary:hover:not(:active) {
        box-shadow: 0 6px 20px var(--accent-glow);
        transform: translateY(-2px);
    }

    .nav-item:hover:not(:active) {
        opacity: 0.8;
        color: var(--accent);
    }
}

/* Large desktop devices (> 1440px) */
@media (min-width: 1440px) {
    :root {
        --font-base: 1.1875rem;
        --font-lg: 1.5rem;
    }

    .container { max-width: 900px; }
    h1 { font-size: 2.5rem; }

    .card { padding: 2rem; }
    .modal-box { max-width: 600px; }
}

/* Landscape orientation optimizations for mobile */
@media (max-height: 600px) and (orientation: landscape) {
    :root {
        --content-padding-bottom: 2rem;
        --spacing-md: 0.75rem;
        --spacing-lg: 1rem;
    }

    h1 { font-size: 1.5rem; }
    h2 { font-size: 1.25rem; }

    .card { padding: var(--spacing-md); margin-bottom: var(--spacing-sm); }
    #main-content { padding: var(--spacing-sm) var(--spacing-md) calc(var(--nav-height) + var(--content-padding-bottom)) var(--spacing-md); }
}

/* Print styles for documentation */
@media print {
    .bottom-nav, .timer-dock, .btn-primary, .btn-secondary { display: none; }
    body { height: auto; }
    #main-content { padding: 1rem; overflow: visible; }
    .card { break-inside: avoid; }
}

/* Accessibility: Reduced motion for users with motion sensitivity */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }

    /* Keep essential transforms but remove transitions */
    .card:active { transform: none; }
    .stepper-btn:active { transform: scale(0.98); transition: none; }
    .set-btn:active { transform: scale(0.98); transition: none; }
    .btn-primary:active { transform: none; }
    .nav-item:active { transform: none; }
    .nav-item.active { transform: none; }
    .timer-dock { transition: none; }
    .modal-overlay { transition: none; }
    .modal-box { transition: none; transform: none; }
    .modal-overlay.active .modal-box { transform: none; }
}