:root {
    --primary: #6366f1;
    --secondary: #4f46e5;
    --background: #111827;
    --surface: #1f2937;
    --on-surface: #f9fafb;
    --on-surface-secondary: #9ca3af;
    --success: #10b981;
    --error: #ef4444;
    --border: #374151;
    --border-focus: var(--primary);
    --focus-ring-color: rgba(99, 102, 241, 0.4);
    --shadow-color-base: rgba(0, 0, 0, 0.1);
    --shadow-color-layer: rgba(0, 0, 0, 0.06);
    --shadow-highlight: rgba(99, 102, 241, 0.3);
    --border-radius-lg: 1rem;
    --border-radius-md: 0.75rem;
    --border-radius-sm: 0.5rem;
    --transition-speed: 0.25s;
    --transition-easing: ease-out;
    --transition-bezier-smooth: cubic-bezier(0.25, 0.1, 0.25, 1);
    --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --font-size-base: 1rem;
    --font-size-sm: 0.9rem;
    --font-size-lg: 1.1rem;
    --button-padding: 0.8rem 1.5rem;
}

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

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    background: var(--background);
    color: var(--on-surface);
    font-family: var(--font-family);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    line-height: 1.6;
    padding: 1rem;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    width: 90%;
    max-width: 700px;
    margin: 2rem auto;
    animation: fadeIn 0.5s var(--transition-easing);
}

.upload-section,
.modal-content,
.success-section,
.restore-draft-bar {
    background: var(--surface);
    border-radius: var(--border-radius-lg);
    box-shadow: 0 4px 6px -1px var(--shadow-color-base), 0 2px 4px -2px var(--shadow-color-layer);
    padding: 2.5rem;
    transition: transform var(--transition-speed) var(--transition-easing), box-shadow var(--transition-speed) var(--transition-easing);
    border: 1px solid var(--border);
}

.upload-section:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 15px -3px var(--shadow-color-base), 0 4px 6px -4px var(--shadow-color-layer);
}

/* Drop zone, button, modal, form, platform styles remain the same... */
.drop-zone {
    border: 2px dashed var(--border);
    border-radius: var(--border-radius-md);
    padding: 2.5rem;
    text-align: center;
    cursor: pointer;
    position: relative;
    margin-bottom: 1.5rem;
    background-color: rgba(0, 0, 0, 0.15);
    min-height: 220px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    transition: border-color var(--transition-speed) var(--transition-easing), background-color var(--transition-speed) var(--transition-easing), box-shadow var(--transition-speed) var(--transition-easing), padding var(--transition-speed) var(--transition-easing);
}

.drop-zone p {
    position: relative;
    z-index: 1;
    color: var(--on-surface-secondary);
    font-weight: 500;
    margin: 0.5rem 0;
    transition: opacity var(--transition-speed) var(--transition-easing), visibility 0s linear var(--transition-speed), height var(--transition-speed) var(--transition-easing);
}

.drop-zone>p,
.drop-zone>button:not(.remove-btn) {
    transition: opacity var(--transition-speed) var(--transition-easing), visibility 0s linear var(--transition-speed), height var(--transition-speed) var(--transition-easing), margin var(--transition-speed) var(--transition-easing), padding var(--transition-speed) var(--transition-easing);
}

.drop-zone p:first-of-type {
    font-size: var(--font-size-lg);
    color: var(--on-surface);
    margin-bottom: 0.8rem;
}

.drop-zone.has-file {
    border-color: var(--primary);
}

.drop-zone.has-file>p,
.drop-zone.has-file>button:not(.remove-btn) {
    visibility: hidden;
    opacity: 0;
    height: 0;
    margin: 0 !important;
    padding: 0 !important;
    border: 0;
    transition: opacity var(--transition-speed) var(--transition-easing) 0s, visibility 0s linear var(--transition-speed), height var(--transition-speed) var(--transition-easing) 0s, margin var(--transition-speed) var(--transition-easing) 0s, padding var(--transition-speed) var(--transition-easing) 0s;
}

#videoDropZone,
#thumbnailDropZone {
    padding: 2.5rem;
}

#thumbnailDropZone.has-file {
    padding: 0.5rem;
}

.thumbnail-preview {
    width: 100%;
    height: 180px;
    background-size: cover;
    background-repeat: no-repeat;
    background-position: center;
    border-radius: var(--border-radius-sm);
    display: none;
    position: relative;
    z-index: 1;
    opacity: 0;
    transition: opacity var(--transition-speed) var(--transition-easing);
}

#thumbnailDropZone.has-file .thumbnail-preview {
    display: block;
    opacity: 1;
}

.video-preview {
    width: 100%;
    text-align: center;
    padding: 1rem;
    display: block;
    position: relative;
    z-index: 1;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed) var(--transition-easing), visibility 0s linear var(--transition-speed);
}

#videoDropZone.has-file .video-preview {
    opacity: 1;
    visibility: visible;
    transition-delay: 0.1s;
}

.video-preview .file-info {
    color: var(--on-surface);
    font-size: var(--font-size-sm);
    word-break: break-all;
}

.drop-zone:hover:not(.has-file) {
    border-color: var(--primary);
    background-color: rgba(99, 102, 241, 0.07);
}

.drop-zone.active {
    border-color: var(--primary);
    border-style: solid;
    background-color: rgba(99, 102, 241, 0.1);
    box-shadow: 0 0 0 4px var(--focus-ring-color);
    animation: pulseBorder 1.5s infinite var(--transition-easing);
}

.drop-zone.error {
    border-color: var(--error);
    border-style: dashed;
    animation: shake 0.5s var(--transition-bezier-smooth);
}

.error-message {
    color: var(--error);
    font-size: var(--font-size-sm);
    margin-top: 0.5rem;
    font-weight: 500;
    display: block;
    position: relative;
    z-index: 1;
    height: auto;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed) var(--transition-easing), visibility 0s linear var(--transition-speed);
}

.drop-zone.error .error-message {
    opacity: 1;
    visibility: visible;
    transition-delay: 0.1s;
}

button {
    background: var(--primary);
    color: var(--on-surface);
    border: none;
    padding: var(--button-padding);
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: all var(--transition-speed) var(--transition-easing);
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    overflow: hidden;
    z-index: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 1rem;
    -webkit-tap-highlight-color: transparent;
}

button:hover:not(:disabled) {
    background: linear-gradient(to bottom, var(--primary), var(--secondary));
    transform: translateY(-2px);
    box-shadow: 0 4px 10px var(--shadow-highlight);
}

button:focus-visible {
    outline: 2px solid transparent;
    outline-offset: 2px;
    box-shadow: 0 0 0 3px var(--focus-ring-color), 0 4px 10px var(--shadow-highlight);
}

button:active:not(:disabled) {
    transform: translateY(-1px) scale(0.97);
    box-shadow: 0 2px 5px var(--shadow-highlight);
    background: var(--secondary);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
    background: var(--primary);
}

.remove-btn {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    background: rgba(30, 30, 45, 0.8);
    color: var(--on-surface);
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 28px;
    height: 28px;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    line-height: 1;
    cursor: pointer;
    z-index: 5;
    transition: background-color var(--transition-speed) var(--transition-easing), transform var(--transition-speed) var(--transition-easing);
    padding: 0;
    margin: 0;
}

.drop-zone.has-file .remove-btn {
    display: flex;
}

.remove-btn:hover {
    background: var(--error);
    transform: scale(1.1) rotate(90deg);
    box-shadow: none;
}

.remove-btn:active {
    transform: scale(1.0) rotate(90deg);
    background-color: #c0392b;
}

.remove-btn:focus-visible {
    outline: 2px solid transparent;
    outline-offset: 2px;
    box-shadow: 0 0 0 3px var(--focus-ring-color);
}

.modal {
    display: none;
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(6px);
    z-index: 1000;
    padding: 1rem;
    overflow-y: auto;
    align-items: center;
    justify-content: center;
    animation: modalFadeIn 0.3s var(--transition-easing);
}

.modal.open {
    display: flex;
}

.modal-content {
    transform: translateY(20px) scale(0.97);
    opacity: 0;
    animation: modalContentSlide 0.35s var(--transition-bezier-smooth) forwards;
    width: 100%;
    max-width: 600px;
    margin: auto;
    position: relative;
    max-height: 90vh;
    overflow-y: auto;
    padding-bottom: 1.5rem;
    box-shadow: 0 10px 15px -3px var(--shadow-color-base), 0 4px 6px -4px var(--shadow-color-layer);
}

#videoPreviewModal .modal-content {
    max-width: 750px;
}

#platformModal .modal-content {
    max-width: 700px;
}

.modal h2 {
    font-weight: 600;
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--on-surface);
}

.close-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 1.75rem;
    line-height: 1;
    cursor: pointer;
    color: var(--on-surface-secondary);
    transition: color var(--transition-speed) var(--transition-easing), transform var(--transition-speed) var(--transition-bezier-smooth);
    z-index: 10;
    background: none;
    border: none;
    padding: 0.5rem;
    border-radius: 50%;
}

.close-btn:hover {
    color: var(--primary);
    transform: rotate(90deg) scale(1.1);
}

.close-btn:focus-visible {
    outline: 2px solid transparent;
    outline-offset: 2px;
    box-shadow: 0 0 0 3px var(--focus-ring-color);
}

#videoPreviewContainer {
    width: 100%;
    background: #000;
    border-radius: var(--border-radius-md);
    overflow: hidden;
    margin-bottom: 1.5rem;
    position: relative;
}

#videoPreviewContainer video {
    display: block;
    width: 100%;
    max-height: 60vh;
    border-radius: var(--border-radius-md);
}

#removePreviewVideoBtn {
    display: none;
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: rgba(0, 0, 0, 0.6);
    border-color: rgba(255, 255, 255, 0.4);
}

.modal-actions {
    text-align: center;
    margin-top: 2rem;
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.6rem;
    font-weight: 500;
    font-size: var(--font-size-sm);
    color: var(--on-surface-secondary);
}

input[type="text"],
input[type="datetime-local"],
textarea {
    width: 100%;
    padding: 0.8rem 1rem;
    border: 1px solid var(--border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    background: var(--background);
    color: var(--on-surface);
    transition: border-color var(--transition-speed) var(--transition-easing), box-shadow var(--transition-speed) var(--transition-easing);
}

input::placeholder,
textarea::placeholder {
    color: var(--on-surface-secondary);
    opacity: 0.6;
    font-size: var(--font-size-sm);
}

input[type="datetime-local"] {
    color-scheme: dark;
    min-height: calc(1.6em + 1.6rem + 2px);
}

input[type="text"]:focus,
input[type="datetime-local"]:focus,
textarea:focus {
    border-color: var(--border-focus);
    outline: none;
    box-shadow: 0 0 0 3px var(--focus-ring-color);
}

textarea {
    resize: vertical;
    min-height: 100px;
    line-height: 1.5;
}

.loading-spinner {
    width: 20px;
    height: 20px;
    border: 3px solid rgba(249, 250, 251, 0.2);
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
    display: none;
}

button.is-loading .loading-spinner {
    display: inline-block;
}

button.is-loading .button-text {
    opacity: 0.7;
    margin-left: -0.5rem;
}

.platform-selection-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 1.5rem;
    margin-top: 1rem;
    margin-bottom: 2rem;
}

.platform-button {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem 1rem;
    border: 2px solid var(--border);
    border-radius: var(--border-radius-md);
    background-color: rgba(255, 255, 255, 0.03);
    cursor: pointer;
    transition: all var(--transition-speed) var(--transition-easing);
    text-align: center;
    margin-top: 0;
    gap: 1rem;
}

.platform-button:hover {
    border-color: var(--primary);
    background-color: rgba(99, 102, 241, 0.1);
    transform: translateY(-3px);
}

.platform-button.selected {
    border-color: var(--success);
    background-color: rgba(16, 185, 129, 0.15);
    box-shadow: 0 0 0 2px var(--success);
}

.platform-button:focus-visible {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px var(--focus-ring-color);
}

.platform-button img {
    width: 72px;
    height: 72px;
    object-fit: contain;
    border-radius: var(--border-radius-sm);
}

.platform-button span {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--on-surface);
}

.platform-button.selected span {
    color: var(--success);
    font-weight: 600;
}

.progress-bar-container {
    width: 100%;
    height: 12px;
    background-color: var(--border);
    border-radius: 6px;
    margin-top: 1.5rem;
    overflow: hidden;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0s 0.3s;
}

.progress-bar-container[aria-hidden="false"] {
    opacity: 1;
    visibility: visible;
    transition: opacity 0.3s ease;
}

.progress-bar {
    width: 0%;
    height: 100%;
    background: linear-gradient(90deg, var(--success), #2ee8a5);
    border-radius: 6px;
    transition: width 0.3s cubic-bezier(0.25, 1, 0.5, 1);
}

.success-section {
    padding: 3rem 2.5rem;
    text-align: center;
    animation: fadeIn 0.5s var(--transition-easing);
}

.success-section h2 {
    color: var(--success);
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

.success-section p {
    color: var(--on-surface-secondary);
    font-size: var(--font-size-lg);
    margin-bottom: 2rem;
}


/* --- ENHANCEMENT STYLES --- */

/* Inline Form Validation Errors */
.inline-error {
    color: var(--error);
    font-size: 0.8rem;
    font-weight: 500;
    margin-left: 0.5rem;
    opacity: 0;
    transition: opacity 0.2s ease-in-out;
}

.inline-error.visible {
    opacity: 1;
}

input.invalid,
textarea.invalid {
    border-color: var(--error) !important;
}

/* Secondary Button Style for Generate Thumbnail */
#generateThumbBtn {
    background: var(--surface);
    border: 1px solid var(--border);
}

#generateThumbBtn:hover:not(:disabled) {
    background: var(--background);
    border-color: var(--primary);
    box-shadow: none;
}

/* Restore Draft Notification Bar */
.restore-draft-bar {
    padding: 1rem 1.5rem;
    margin-bottom: 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    border-left: 4px solid var(--primary);
}

.restore-draft-bar p {
    margin: 0;
    color: var(--on-surface-secondary);
    font-weight: 500;
}

.restore-draft-actions {
    display: flex;
    gap: 0.75rem;
}

.restore-draft-actions button {
    margin-top: 0;
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}

.restore-draft-actions .dismiss-btn {
    background: none;
    border: 1px solid var(--border);
}

.restore-draft-actions .dismiss-btn:hover {
    background: var(--error);
    border-color: var(--error);
}

/* Animation keyframes remain the same */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulseBorder {
    0% {
        box-shadow: 0 0 0 0 var(--focus-ring-color);
    }

    70% {
        box-shadow: 0 0 0 8px rgba(99, 102, 241, 0);
    }

    100% {
        box-shadow: 0 0 0 0 rgba(99, 102, 241, 0);
    }
}

@keyframes shake {
    0% {
        transform: translateX(0);
    }

    10%,
    90% {
        transform: translateX(-4px);
    }

    30%,
    70% {
        transform: translateX(4px);
    }

    50% {
        transform: translateX(-2px);
    }
}

@keyframes modalFadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes modalContentSlide {
    to {
        transform: translateY(0) scale(1);
        opacity: 1;
    }
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}