/* Base styles */
:root {
    --bs-body-font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --primary-color: #000000;
    --secondary-color: #ffffff;
    --accent-color: #666666;
    --border-color: #e0e0e0;
    --hover-color: #f5f5f5;
    --text-primary: #000000;
    --text-secondary: #666666;
}

body {
    font-family: var(--bs-body-font-family);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    font-size: 0.9375rem;
    line-height: 1.5;
    background-color: var(--secondary-color);
    color: var(--text-primary);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--bs-body-font-family);
    font-weight: 600;
    margin-bottom: 1rem;
}

.display-2 {
    font-weight: 700;
}

.lead {
    font-weight: 400;
}

/* Navigation styles */
.navbar.navbar-expand-lg {
    font-family: var(--bs-body-font-family);
    padding: 0.75rem 1rem;
    background-color: var(--secondary-color) !important;
    border-bottom: 1px solid var(--border-color);
}

.navbar .navbar-brand {
    font-weight: 600;
    display: flex;
    align-items: center;
    color: var(--text-primary) !important;
}

.navbar .nav-link {
    padding: 0.5rem 1rem;
    font-weight: 500;
    color: var(--text-primary) !important;
    transition: color 0.2s ease;
}

.navbar .nav-link:hover {
    color: var(--text-secondary) !important;
    filter: brightness(0.8);
}

/* Mobile hamburger menu styling */
.navbar-toggler {
    border: 1px solid var(--text-primary) !important;
    padding: 0.25rem 0.5rem;
}

.navbar-toggler:focus {
    box-shadow: 0 0 0 0.2rem rgba(0, 0, 0, 0.25);
}

.navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba%2833, 37, 41, 0.75%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e") !important;
    width: 1.5em;
    height: 1.5em;
}

/* Video History Card Styles */
.video-history-card {
    transition: all 0.2s ease-in-out;
    border-radius: 0.5rem;
    overflow: hidden;
    background-color: var(--secondary-color);
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.video-history-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    filter: contrast(1.05) brightness(0.98);
}

.video-thumbnail-container {
    position: relative;
    padding-top: 56.25%; /* 16:9 Aspect Ratio */
    overflow: hidden;
    background-color: var(--bs-dark);
}

.video-thumbnail {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

.video-history-card:hover .video-thumbnail {
    transform: scale(1.05);
}

/* Layout and spacing */
.container {
    max-width: 1140px;
    padding: 0 1rem;
}

.card {
    margin-bottom: 1rem;
}

/* Tab styles */
.nav-tabs .nav-link {
    transition: color 0.2s ease, background-color 0.2s ease, filter 0.3s ease;
}

.nav-tabs .nav-link:not(.active) {
    color: var(--text-primary);  /* Black text for inactive tabs */
}

.nav-tabs .nav-link:hover:not(.active) {
    color: var(--text-secondary);  /* Gray text on hover for inactive tabs */
    filter: brightness(0.95);
}

.nav-tabs .nav-link.active {
    color: var(--secondary-color) !important;  /* White text */
    background-color: var(--text-primary) !important;  /* Black background */
    border-color: var(--text-primary);
    filter: none;
}

/* Form control hover effects */
.form-control:hover {
    filter: brightness(0.98);
    transition: filter 0.3s ease;
}

/* Flashcard hover effects */
.flashcard:hover {
    filter: contrast(1.02) brightness(0.98);
    transition: filter 0.3s ease;
}
.nav-tabs {
    margin-bottom: 1rem;
}

/* Buttons and forms */
.btn {
    font-family: var(--bs-body-font-family);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 0.25rem;
    transition: all 0.2s ease, filter 0.3s ease;
}

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

.btn-primary:hover {
    background-color: var(--text-secondary);
    border-color: var(--text-secondary);
    filter: contrast(1.1) brightness(0.95);
}

.btn-lg {
    padding: 0.75rem 1.25rem;
}

.form-control {
    font-family: var(--bs-body-font-family);
    font-size: 0.9375rem;
    border: 1px solid var(--border-color);
    border-radius: 0.25rem;
    transition: border-color 0.2s ease;
}

.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(0, 0, 0, 0.1);
}

.form-control-lg {
    font-size: 1.125rem;
}

/* Flashcard styles */
.flashcard {
    perspective: 1000px;
    height: 250px;
    cursor: pointer;
    position: relative;
    transform-style: preserve-3d;
    margin-bottom: 1rem;
}

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

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform 0.6s;
}

.flashcard-front,
.flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
}

.flashcard-front .card,
.flashcard-back .card {
    height: 100%;
    margin: 0;
}

.flashcard-front .card-body,
.flashcard-back .card-body {
    padding: 1rem;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.flashcard-front .card-title,
.flashcard-back .card-title {
    margin-bottom: 0.75rem;
    font-size: 1.1rem;
}

.flashcard-front .card-text,
.flashcard-back .card-text {
    overflow-y: auto;
    word-wrap: break-word;
    flex-grow: 1;
    font-size: 0.95rem;
    padding-right: 0.5rem;
}

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

/* Quiz styles */
.correct-answer {
    color: var(--bs-success) !important;
    font-weight: 500;
}

.incorrect-answer {
    color: var(--bs-danger) !important;
    text-decoration: line-through;
}

/* Loading spacing */
#spacing-div {
    height: 40px;
    display: none;
}

/* Footer positioning and styles */
body > .footer,
.footer.footer {
    background-color: var(--secondary-color) !important;
    border-top: 1px solid var(--border-color);
    padding: 1rem 0;
    margin-top: auto;
    font-family: var(--bs-body-font-family);
    position: relative;
    bottom: 0;
    width: 100%;
}

.footer.footer a {
    color: var(--text-primary);
    transition: color 0.2s ease;
}

.footer.footer a:hover {
    color: var(--text-secondary);
    text-decoration: none;
}

/* Transcript styles */
.transcript-container {
    position: relative;
    width: 100%;
    border-radius: 0.375rem;
    background-color: var(--bs-dark);
    border: 1px solid var(--bs-border-color);
}

#transcript-content {
    max-height: 500px;
    overflow-y: auto;
    white-space: pre-wrap;
    word-wrap: break-word;
    overflow-wrap: break-word;
    font-family: var(--bs-font-monospace);
    font-size: 0.875rem;
    line-height: 1.5;
    padding: 1.25rem;
    color: var(--bs-light);
    margin: 0;
    width: 100%;
    box-sizing: border-box;
}

/* Spacing utilities */
.mt-4 {
    margin-top: 1.5rem !important;
}

.mb-3 {
    margin-bottom: 1rem !important;
}

.mb-4 {
    margin-bottom: 1.5rem !important;
}

.gap-2 {
    gap: 0.5rem !important;
}

.me-1 {
    margin-right: 0.25rem !important;
}

/* Alert styles */
.alert {
    font-family: var(--bs-body-font-family);
    margin-bottom: 1rem;
    padding: 0.75rem 1.25rem;
}


/* ---------- Home page (minimal) ---------- */
.hero {
    max-width: 640px;
    margin: 4.5rem auto 3.5rem;
    text-align: center;
}

.hero-title {
    font-size: clamp(2.25rem, 5vw, 3.25rem);
    font-weight: 600;
    letter-spacing: -0.02em;
    margin-bottom: 0.75rem;
}

.hero-sub {
    color: var(--text-secondary);
    font-size: 1.0625rem;
    margin-bottom: 2rem;
}

.source-tabs {
    display: inline-flex;
    gap: 0.25rem;
    padding: 0.25rem;
    border: 1px solid var(--border-color);
    border-radius: 999px;
    margin-bottom: 1.25rem;
}

.source-tab {
    border: 0;
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    padding: 0.375rem 0.875rem;
    border-radius: 999px;
    transition: background-color 0.15s ease, color 0.15s ease;
}

.source-tab:hover { color: var(--text-primary); }

.source-tab.is-active {
    background: var(--text-primary);
    color: var(--secondary-color);
}

.input-row {
    display: flex;
    gap: 0.5rem;
    width: 100%;
}

.input-main {
    flex: 1;
    min-width: 0;
    font-size: 1rem;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background: var(--secondary-color);
    color: var(--text-primary);
}

.input-main:focus {
    border-color: var(--text-primary);
    box-shadow: none;
    outline: none;
}

.input-main::placeholder { color: #9a9a9a; }

.btn-go {
    background: var(--text-primary);
    color: var(--secondary-color);
    border: 1px solid var(--text-primary);
    border-radius: 0.5rem;
    padding: 0.75rem 1.25rem;
    font-weight: 500;
    white-space: nowrap;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-go:hover { background: #222; color: #fff; }
.btn-go .spinner-border { display: none; width: 0.9rem; height: 0.9rem; }
.btn-go.loading .spinner-border { display: inline-block; }
.btn-go.loading { cursor: not-allowed; opacity: 0.8; }

.file-drop {
    flex: 1;
    min-width: 0;
    position: relative;
    display: flex;
    align-items: center;
    padding: 0.75rem 1rem;
    border: 1px dashed #c8c8c8;
    border-radius: 0.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    margin: 0;
    text-align: left;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
}

.file-drop:hover { border-color: var(--text-primary); color: var(--text-primary); }

.file-drop input[type="file"] {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
}

.hero-loading {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 1.25rem;
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

.hero #error-container {
    text-align: left;
    border-radius: 0.5rem;
    margin-top: 1rem;
}

.examples {
    max-width: 640px;
    margin: 0 auto 3rem;
}

.examples-label {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.8125rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: 1rem;
}

.example-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1rem;
}

.example-grid .carousel-item {
    display: block;
    float: none;
    width: auto;
    margin: 0;
    transform: none;
    transition: none;
    cursor: pointer;
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    overflow: hidden;
    background: var(--secondary-color);
}

.example-grid .carousel-item:hover { border-color: var(--text-primary); }

.example-grid .carousel-content {
    aspect-ratio: 16/9;
    background: #f2f2f2;
}

.example-grid .carousel-content img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.example-grid .carousel-caption {
    position: static;
    background: none;
    padding: 0.75rem 0.875rem 0.875rem;
    text-align: left;
}

.example-grid .carousel-caption h5 {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0 0 0.125rem;
}

.example-grid .carousel-caption p {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    margin: 0;
}

.example-grid .carousel-caption small { display: none; }

/* Footer links */
.footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    font-size: 0.8125rem;
}

.footer-links a,
.footer-links button {
    color: var(--text-secondary);
    text-decoration: none;
    background: none;
    border: 0;
    padding: 0;
}

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

@media (max-width: 480px) {
    .hero { margin-top: 2.5rem; }
    .input-row { flex-direction: column; }
    .btn-go { justify-content: center; }
}