/* SIE Formula Flashcard Styles
 * Mobile-first design for formula reference cards
 * Requires main.css to be loaded first for CSS variables
 */

/* ============================================
   Base Reset
   ============================================ */
html,
body {
    overscroll-behavior: none;
    touch-action: pan-x pan-y;
    height: -webkit-fill-available;
}

html {
    height: -webkit-fill-available;
}

body {
    margin: 0;
    padding: 0;
    font-family: var(--fh-font-body);
    background: #1a1f2e;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    min-height: 100vh;
    min-height: -webkit-fill-available;
    position: fixed;
    width: 100%;
    overflow: hidden;
}

/* ============================================
   Back Link
   ============================================ */
.back-link {
    position: fixed;
    top: calc(var(--fh-space-sm) + env(safe-area-inset-top));
    left: calc(var(--fh-space-sm) + env(safe-area-inset-left));
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--fh-space-xs);
    padding: var(--fh-space-xs) var(--fh-space-sm);
    min-width: 44px;
    min-height: 44px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--fh-white);
    text-decoration: none;
    background: rgba(0, 45, 98, 0.95);
    border-radius: 22px;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: background-color 0.15s ease;
    -webkit-tap-highlight-color: transparent;
}

.back-link:hover {
    background: var(--fh-navy);
}

.back-link:active {
    transform: scale(0.95);
}

.back-link__icon {
    font-size: 1rem;
}

@media (max-width: 360px) {
    .back-link span:not(.back-link__icon) {
        display: none;
    }
    .back-link {
        padding: var(--fh-space-xs);
    }
}

/* ============================================
   Formula App Container
   ============================================ */
.formula-app {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    min-height: 100dvh;
    min-height: -webkit-fill-available;
    background: #1a1f2e;
    overflow: hidden;
    padding-left: env(safe-area-inset-left);
    padding-right: env(safe-area-inset-right);
    padding-bottom: env(safe-area-inset-bottom);
}

/* ============================================
   Header
   ============================================ */
.formula-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--fh-space-sm) var(--fh-space-md);
    padding-top: calc(var(--fh-space-sm) + env(safe-area-inset-top));
    background: var(--fh-navy);
    color: var(--fh-white);
    padding-left: 72px;
    min-height: 44px;
    flex-shrink: 0;
}

@media (max-width: 360px) {
    .formula-header {
        padding-left: 64px;
        padding-right: var(--fh-space-sm);
    }
}

.formula-title {
    font-family: var(--fh-font-display);
    font-size: 1rem;
    font-weight: 600;
    color: var(--fh-white);
    margin: 0;
}

.formula-progress {
    font-family: var(--fh-font-mono);
    font-size: 0.875rem;
    font-weight: 500;
    opacity: 0.9;
}

/* ============================================
   Start Screen
   ============================================ */
.formula-start-screen {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--fh-space-xl);
    text-align: center;
}

.start-content {
    max-width: 320px;
    width: 100%;
}

.start-icon {
    font-size: 4rem;
    margin-bottom: var(--fh-space-lg);
}

.start-title {
    font-family: var(--fh-font-display);
    font-size: 1.75rem;
    color: #e8eaed;
    margin-bottom: var(--fh-space-sm);
}

.start-description {
    color: rgba(255, 255, 255, 0.6);
    margin-bottom: var(--fh-space-xl);
    line-height: 1.6;
}

.start-stats {
    display: flex;
    justify-content: center;
    gap: var(--fh-space-xl);
    margin-bottom: var(--fh-space-xl);
    padding: var(--fh-space-lg);
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--fh-space-xs);
}

.stat__value {
    font-family: var(--fh-font-mono);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--fh-sage);
}

.stat__label {
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.5);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--fh-space-md) var(--fh-space-xl);
    font-family: var(--fh-font-body);
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition:
        transform 0.15s ease,
        box-shadow 0.15s ease,
        background-color 0.15s ease;
    min-height: 48px;
    min-width: 48px;
    -webkit-tap-highlight-color: transparent;
}

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

.btn--primary:hover {
    background: #003a7d;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 45, 98, 0.3);
}

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

.btn--secondary {
    background: transparent;
    color: rgba(255, 255, 255, 0.7);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn--secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--fh-white);
}

.btn--start {
    width: 100%;
    padding: var(--fh-space-lg) var(--fh-space-xl);
    font-size: 1.125rem;
}

.btn--small {
    padding: var(--fh-space-sm) var(--fh-space-md);
    font-size: 0.875rem;
    min-height: 40px;
}

/* ============================================
   Session View
   ============================================ */
.formula-session {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: var(--fh-space-sm) var(--fh-space-md);
    padding-bottom: 0;
    overflow: hidden;
    min-height: 0;
    gap: var(--fh-space-sm);
}

/* Progress Bar */
.session-progress {
    display: flex;
    align-items: center;
    gap: var(--fh-space-md);
    flex-shrink: 0;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    overflow: hidden;
}

.progress-bar__fill {
    height: 100%;
    background: linear-gradient(90deg, var(--fh-sage), #8fb099);
    border-radius: 4px;
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.875rem;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.7);
    white-space: nowrap;
    font-family: var(--fh-font-mono);
    min-width: 7ch;
    text-align: right;
}

/* Session Counters */
.session-counters {
    display: flex;
    justify-content: center;
    gap: var(--fh-space-xl);
    flex-shrink: 0;
}

.counter {
    display: flex;
    align-items: center;
    gap: var(--fh-space-sm);
}

.counter__value {
    font-size: 1.25rem;
    font-weight: 700;
    font-family: var(--fh-font-mono);
    min-width: 2ch;
    text-align: center;
}

.counter__label {
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.02em;
    color: rgba(255, 255, 255, 0.5);
}

.counter--know .counter__value {
    color: var(--fh-sage);
}

.counter--review .counter__value {
    color: var(--fh-burgundy);
}

/* ============================================
   Flashcard Container
   ============================================ */
.flashcard-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    perspective: 1000px;
    touch-action: none;
    user-select: none;
    min-height: 0;
    padding: var(--fh-space-sm);
}

/* ============================================
   Flashcard
   ============================================ */
.flashcard {
    width: 100%;
    max-width: 380px;
    height: auto;
    min-height: 280px;
    cursor: pointer;
    transform-style: preserve-3d;
    transform-origin: center center;
    transition: transform 0.4s ease;
    position: relative;
}

@media (min-width: 380px) and (min-height: 800px) {
    .flashcard {
        max-width: 360px;
        min-height: 300px;
    }
}

@media (min-height: 900px) {
    .flashcard {
        max-width: 420px;
        min-height: 340px;
    }
}

.flashcard--flipped {
    transform: rotateY(180deg);
}

.flashcard__inner {
    position: relative;
    width: 100%;
    min-height: inherit;
    transform-style: preserve-3d;
}

.flashcard__front,
.flashcard__back {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--fh-space-xl);
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    border-radius: 20px;
    box-shadow:
        0 8px 32px rgba(0, 0, 0, 0.3),
        0 16px 48px rgba(0, 0, 0, 0.2);
    min-height: 280px;
}

.flashcard__front {
    position: relative;
    width: 100%;
    background: #2a3142;
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.flashcard__back {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #1e3a5f;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transform: rotateY(180deg);
    padding: var(--fh-space-lg);
}

@media (min-width: 500px) {
    .flashcard__front,
    .flashcard__back {
        padding: var(--fh-space-2xl);
        border-radius: 24px;
    }
}

/* Priority Badge */
.priority-badge {
    position: absolute;
    top: var(--fh-space-md);
    right: var(--fh-space-md);
    padding: var(--fh-space-xs) var(--fh-space-sm);
    font-size: 0.625rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: 4px;
    color: var(--fh-white);
}

.priority-badge--most-common {
    background: var(--fh-burgundy);
}

.priority-badge--very-common {
    background: var(--fh-gold);
}

.priority-badge--occasional {
    background: var(--fh-gray-600);
}

/* Card Front - Formula Name */
.formula-name {
    font-family: var(--fh-font-display);
    font-size: clamp(1.5rem, 6vw, 2rem);
    font-weight: 500;
    color: #e8eaed;
    text-align: center;
    line-height: 1.3;
}

.tap-hint {
    position: absolute;
    bottom: var(--fh-space-lg);
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.4);
}

/* Card Back - Formula */
.formula-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--fh-space-lg);
    width: 100%;
}

.formula-equation {
    font-family: var(--fh-font-mono);
    font-size: clamp(1.25rem, 5vw, 1.75rem);
    font-weight: 500;
    color: var(--fh-sage);
    text-align: center;
    padding: var(--fh-space-md);
    background: rgba(0, 0, 0, 0.2);
    border-radius: 8px;
    width: 100%;
    line-height: 1.4;
}

.formula-variables {
    font-size: 0.9375rem;
    color: rgba(255, 255, 255, 0.85);
    text-align: center;
    line-height: 1.8;
}

.formula-variables p {
    margin: 0;
}

.formula-warning {
    font-size: 0.875rem;
    color: var(--fh-gold);
    text-align: center;
    margin-top: var(--fh-space-sm);
}

/* Swipe Feedback */
.flashcard--swiping-right {
    box-shadow: 0 0 40px rgba(124, 152, 133, 0.5);
}

.flashcard--swiping-left {
    box-shadow: 0 0 40px rgba(107, 39, 55, 0.5);
}

/* ============================================
   Action Buttons
   ============================================ */
.action-buttons {
    display: flex;
    justify-content: center;
    gap: var(--fh-space-md);
    padding: var(--fh-space-md);
    padding-bottom: calc(var(--fh-space-lg) + env(safe-area-inset-bottom));
    flex-shrink: 0;
}

.action-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--fh-space-sm);
    padding: var(--fh-space-md) var(--fh-space-xl);
    flex: 1;
    max-width: 180px;
    min-height: 56px;
    font-family: var(--fh-font-body);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.02em;
    border: none;
    border-radius: 16px;
    cursor: pointer;
    transition:
        transform 0.12s ease,
        box-shadow 0.12s ease;
    -webkit-tap-highlight-color: transparent;
}

.action-btn__icon {
    font-size: 1.25rem;
}

.action-btn--review {
    background: var(--fh-burgundy);
    color: var(--fh-white);
    box-shadow: 0 4px 12px rgba(107, 39, 55, 0.3);
}

.action-btn--review:hover {
    background: #7a3040;
}

.action-btn--review:active {
    transform: scale(0.97);
}

.action-btn--know {
    background: var(--fh-sage);
    color: var(--fh-white);
    box-shadow: 0 4px 12px rgba(124, 152, 133, 0.3);
}

.action-btn--know:hover {
    background: #8ba990;
}

.action-btn--know:active {
    transform: scale(0.97);
}

@media (max-width: 360px) {
    .action-buttons {
        flex-direction: column;
        gap: var(--fh-space-sm);
    }
    .action-btn {
        max-width: 100%;
    }
}

/* ============================================
   Review Pile Banner
   ============================================ */
.review-banner {
    display: none;
    align-items: center;
    justify-content: center;
    gap: var(--fh-space-sm);
    padding: var(--fh-space-sm) var(--fh-space-md);
    background: rgba(107, 39, 55, 0.3);
    color: var(--fh-white);
    font-size: 0.875rem;
    flex-shrink: 0;
}

.review-banner--visible {
    display: flex;
}

.review-banner__count {
    font-weight: 600;
    color: var(--fh-burgundy);
    background: rgba(255, 255, 255, 0.9);
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.75rem;
}

/* ============================================
   Summary Screen
   ============================================ */
.formula-summary {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--fh-space-lg);
    padding-bottom: calc(var(--fh-space-lg) + env(safe-area-inset-bottom));
}

.summary-content {
    text-align: center;
    max-width: 400px;
    width: 100%;
}

.summary-icon {
    font-size: 4rem;
    margin-bottom: var(--fh-space-lg);
}

.summary-title {
    font-family: var(--fh-font-display);
    font-size: 1.75rem;
    color: #e8eaed;
    margin-bottom: var(--fh-space-md);
}

.summary-message {
    color: rgba(255, 255, 255, 0.6);
    margin-bottom: var(--fh-space-xl);
    line-height: 1.6;
}

.summary-stats {
    display: flex;
    justify-content: center;
    gap: var(--fh-space-xl);
    margin-bottom: var(--fh-space-xl);
}

.summary-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--fh-space-xs);
}

.summary-stat__value {
    font-family: var(--fh-font-display);
    font-size: 2rem;
    font-weight: 600;
}

.summary-stat--know .summary-stat__value {
    color: var(--fh-sage);
}

.summary-stat--review .summary-stat__value {
    color: var(--fh-burgundy);
}

.summary-stat__label {
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.5);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.summary-actions {
    display: flex;
    flex-direction: column;
    gap: var(--fh-space-md);
}

.summary-actions .btn {
    min-height: 52px;
}

/* ============================================
   Responsive Adjustments
   ============================================ */
@media (min-width: 768px) {
    .flashcard {
        width: 70%;
        max-width: 500px;
    }

    .summary-actions {
        flex-direction: row;
        justify-content: center;
    }
}

@media (min-width: 1024px) {
    .formula-app {
        max-width: 800px;
        margin: 0 auto;
        min-height: calc(100vh - 4rem);
        border-radius: 0 0 16px 16px;
        box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    }
}

/* ============================================
   Landscape Mode
   ============================================ */
@media (max-height: 500px) and (orientation: landscape) {
    .formula-header {
        padding-top: var(--fh-space-xs);
        padding-bottom: var(--fh-space-xs);
        min-height: 36px;
    }

    .formula-title {
        font-size: 0.875rem;
    }

    .formula-session {
        flex-direction: row;
        padding: var(--fh-space-xs) var(--fh-space-md);
        gap: var(--fh-space-md);
    }

    .session-progress {
        display: none;
    }

    .session-counters {
        flex-direction: column;
        justify-content: center;
        gap: var(--fh-space-sm);
        min-width: 80px;
    }

    .flashcard-container {
        flex: 1;
        padding: var(--fh-space-xs);
    }

    .flashcard {
        min-height: 180px;
    }

    .flashcard__front,
    .flashcard__back {
        padding: var(--fh-space-md);
        border-radius: 12px;
        min-height: 180px;
    }

    .action-buttons {
        flex-direction: column;
        justify-content: center;
        padding: var(--fh-space-xs);
        gap: var(--fh-space-sm);
    }

    .action-btn {
        flex-direction: column;
        min-width: 70px;
        max-width: 70px;
        min-height: 70px;
        padding: var(--fh-space-sm);
        font-size: 0.625rem;
    }
}

/* ============================================
   Accessibility
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    .flashcard,
    .progress-bar__fill,
    .btn {
        transition: none;
    }

    .flashcard--flipped {
        transform: none;
    }

    .flashcard--flipped .flashcard__front {
        visibility: hidden;
    }

    .flashcard--flipped .flashcard__back {
        transform: none;
        visibility: visible;
    }
}

.btn:focus-visible {
    outline: 3px solid var(--fh-gold);
    outline-offset: 2px;
}

.flashcard:focus-visible {
    outline: 3px solid var(--fh-gold);
    outline-offset: 4px;
}