/* ============================================================
   MP3 Volume Booster - Custom Styles
   All classes prefixed with .mvb- to avoid conflicts with
   Google AdSense auto ads and third-party scripts.
   ============================================================ */

/* --- CSS Custom Properties --- */
:root {
    --mvb-primary: #2563eb;
    --mvb-primary-hover: #1d4ed8;
    --mvb-primary-light: #dbeafe;
    --mvb-secondary: #0d9488;
    --mvb-secondary-hover: #0f766e;
    --mvb-text: #1e293b;
    --mvb-text-muted: #64748b;
    --mvb-bg: #f8fafc;
    --mvb-white: #ffffff;
    --mvb-border: #e2e8f0;
    --mvb-error: #dc2626;
    --mvb-error-bg: #fef2f2;
    --mvb-warning: #d97706;
    --mvb-warning-bg: #fffbeb;
    --mvb-success: #16a34a;
    --mvb-success-bg: #f0fdf4;
    --mvb-shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --mvb-shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
    --mvb-shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
    --mvb-shadow-lg: 0 10px 15px rgba(0,0,0,0.1), 0 4px 6px rgba(0,0,0,0.05);
    --mvb-radius: 8px;
    --mvb-radius-lg: 12px;
    --mvb-font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --mvb-maxw: 900px;
}

/* --- Page Container --- */
.mvb-page {
    font-family: var(--mvb-font);
    color: var(--mvb-text);
    background: var(--mvb-bg);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.mvb-container {
    max-width: var(--mvb-maxw);
    margin: 0 auto;
    padding: 0 20px;
}

/* --- Header --- */
.mvb-header {
    background: linear-gradient(135deg, var(--mvb-primary) 0%, var(--mvb-secondary) 100%);
    color: var(--mvb-white);
    padding: 40px 0 36px;
    text-align: center;
}

.mvb-logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    margin-bottom: 8px;
}

.mvb-logo-icon {
    color: var(--mvb-white);
    flex-shrink: 0;
}

.mvb-title {
    font-size: 2rem;
    font-weight: 700;
    margin: 0;
    letter-spacing: -0.02em;
}

.mvb-subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
    margin: 0;
    font-weight: 400;
}

/* --- Main Content --- */
.mvb-main {
    padding: 32px 0 48px;
}

/* --- Sections --- */
.mvb-section {
    margin-bottom: 36px;
}

.mvb-section-title {
    font-size: 1.35rem;
    font-weight: 600;
    margin: 0 0 16px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--mvb-text);
}

.mvb-step-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    background: var(--mvb-primary);
    color: var(--mvb-white);
    font-size: 0.85rem;
    font-weight: 700;
    flex-shrink: 0;
}

/* --- Upload Area --- */
.mvb-upload-area {
    border: 2px dashed var(--mvb-border);
    border-radius: var(--mvb-radius-lg);
    padding: 40px 24px;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s, background 0.2s;
    background: var(--mvb-white);
    position: relative;
}

.mvb-upload-area:hover,
.mvb-upload-area:focus-visible {
    border-color: var(--mvb-primary);
    background: var(--mvb-primary-light);
    outline: none;
}

.mvb-upload-area.mvb-dragover {
    border-color: var(--mvb-primary);
    background: var(--mvb-primary-light);
    border-style: solid;
}

.mvb-upload-icon {
    color: var(--mvb-text-muted);
    margin-bottom: 12px;
}

.mvb-upload-text {
    font-size: 1.05rem;
    font-weight: 500;
    margin: 0 0 4px;
    color: var(--mvb-text);
}

.mvb-upload-hint {
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
    margin: 0;
}

.mvb-file-input {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
    width: 100%;
    height: 100%;
}

.mvb-file-status {
    margin-top: 12px;
    font-size: 0.95rem;
    min-height: 1.6em;
}

.mvb-file-status.mvb-status-ready {
    color: var(--mvb-success);
    font-weight: 500;
}

.mvb-file-status.mvb-status-error {
    color: var(--mvb-error);
    font-weight: 500;
}

/* --- Volume Control --- */
.mvb-volume-section .mvb-volume-control {
    background: var(--mvb-white);
    border-radius: var(--mvb-radius-lg);
    padding: 24px;
    box-shadow: var(--mvb-shadow);
}

.mvb-volume-labels {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
    font-size: 0.85rem;
    color: var(--mvb-text-muted);
}

.mvb-volume-label-current {
    font-weight: 600;
    color: var(--mvb-primary);
    font-size: 1rem;
}

.mvb-slider-row {
    margin-bottom: 16px;
}

/* Custom Range Slider */
.mvb-volume-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 8px;
    border-radius: 4px;
    background: linear-gradient(to right, var(--mvb-primary) 0%, var(--mvb-primary) var(--mvb-slider-pct, 20%), var(--mvb-border) var(--mvb-slider-pct, 20%), var(--mvb-border) 100%);
    outline: none;
    transition: background 0.1s;
    cursor: pointer;
}

.mvb-volume-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--mvb-primary);
    border: 3px solid var(--mvb-white);
    box-shadow: var(--mvb-shadow-md);
    cursor: pointer;
    transition: transform 0.15s;
}

.mvb-volume-slider::-webkit-slider-thumb:hover {
    transform: scale(1.15);
}

.mvb-volume-slider::-moz-range-thumb {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--mvb-primary);
    border: 3px solid var(--mvb-white);
    box-shadow: var(--mvb-shadow-md);
    cursor: pointer;
}

.mvb-volume-slider::-moz-range-track {
    height: 8px;
    border-radius: 4px;
    background: var(--mvb-border);
}

.mvb-volume-input-row {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.mvb-volume-input-label {
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--mvb-text);
}

.mvb-volume-input {
    width: 80px;
    padding: 8px 10px;
    border: 1px solid var(--mvb-border);
    border-radius: var(--mvb-radius);
    font-size: 1rem;
    text-align: center;
    font-family: var(--mvb-font);
    color: var(--mvb-text);
    transition: border-color 0.2s;
}

.mvb-volume-input:focus {
    outline: none;
    border-color: var(--mvb-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.mvb-volume-percent {
    font-weight: 500;
    color: var(--mvb-text-muted);
}

.mvb-volume-desc {
    margin: 12px 0 0;
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
}

.mvb-volume-warning {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 12px;
    padding: 10px 14px;
    background: var(--mvb-warning-bg);
    color: var(--mvb-warning);
    border-radius: var(--mvb-radius);
    font-size: 0.9rem;
    font-weight: 500;
}

/* --- Buttons --- */
.mvb-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 22px;
    font-size: 0.95rem;
    font-weight: 600;
    font-family: var(--mvb-font);
    border: none;
    border-radius: var(--mvb-radius);
    cursor: pointer;
    transition: background 0.2s, opacity 0.2s, transform 0.1s;
    text-decoration: none;
    line-height: 1.4;
}

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

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

.mvb-btn-primary:hover {
    background: var(--mvb-primary-hover);
}

.mvb-btn-primary:disabled {
    background: #94a3b8;
    cursor: not-allowed;
    transform: none;
}

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

.mvb-btn-secondary:hover {
    background: #cbd5e1;
}

.mvb-btn-download {
    background: var(--mvb-secondary);
    color: var(--mvb-white);
    margin-top: 12px;
}

.mvb-btn-download:hover {
    background: var(--mvb-secondary-hover);
}

/* Button loading state */
.mvb-btn.mvb-loading .mvb-btn-text {
    visibility: hidden;
}

.mvb-btn-loading {
    display: none;
}

.mvb-btn.mvb-loading .mvb-btn-loading {
    display: block;
    width: 18px;
    height: 18px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: var(--mvb-white);
    border-radius: 50%;
    animation: mvb-spin 0.7s linear infinite;
    position: absolute;
}

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

/* --- Action Cards --- */
.mvb-action-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.mvb-action-card {
    background: var(--mvb-white);
    border-radius: var(--mvb-radius-lg);
    padding: 24px;
    box-shadow: var(--mvb-shadow);
    text-align: center;
}

.mvb-action-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 0 0 8px;
    color: var(--mvb-text);
}

.mvb-action-desc {
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
    margin: 0 0 16px;
    line-height: 1.5;
}

/* --- Output Section --- */
.mvb-output-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.mvb-output-card {
    background: var(--mvb-white);
    border-radius: var(--mvb-radius-lg);
    padding: 24px;
    box-shadow: var(--mvb-shadow);
}

.mvb-output-title {
    font-size: 1rem;
    font-weight: 600;
    margin: 0 0 14px;
    color: var(--mvb-text);
}

.mvb-audio-player {
    width: 100%;
    border-radius: var(--mvb-radius);
}

/* --- Error Display --- */
.mvb-error {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    background: var(--mvb-error-bg);
    color: var(--mvb-error);
    padding: 14px 18px;
    border-radius: var(--mvb-radius);
    font-size: 0.95rem;
    font-weight: 500;
    margin-bottom: 24px;
    border: 1px solid #fecaca;
}

.mvb-error-text {
    flex: 1;
}

.mvb-error-close {
    background: none;
    border: none;
    color: var(--mvb-error);
    font-size: 1.3rem;
    cursor: pointer;
    padding: 0 4px;
    line-height: 1;
    font-family: var(--mvb-font);
}

/* --- How It Works --- */
.mvb-steps-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.mvb-step-card {
    background: var(--mvb-white);
    border-radius: var(--mvb-radius-lg);
    padding: 28px 20px;
    text-align: center;
    box-shadow: var(--mvb-shadow);
    transition: box-shadow 0.2s;
}

.mvb-step-card:hover {
    box-shadow: var(--mvb-shadow-md);
}

.mvb-step-icon {
    color: var(--mvb-primary);
    margin-bottom: 12px;
}

.mvb-step-title {
    font-size: 1.05rem;
    font-weight: 600;
    margin: 0 0 8px;
    color: var(--mvb-text);
}

.mvb-step-desc {
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
    margin: 0;
    line-height: 1.5;
}

/* --- Features --- */
.mvb-features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.mvb-feature-card {
    background: var(--mvb-white);
    border-radius: var(--mvb-radius-lg);
    padding: 24px 20px;
    box-shadow: var(--mvb-shadow);
    transition: box-shadow 0.2s;
}

.mvb-feature-card:hover {
    box-shadow: var(--mvb-shadow-md);
}

.mvb-feature-title {
    font-size: 1rem;
    font-weight: 600;
    margin: 0 0 8px;
    color: var(--mvb-text);
}

.mvb-feature-desc {
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
    margin: 0;
    line-height: 1.5;
}

/* --- FAQ --- */
.mvb-faq-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.mvb-faq-item {
    background: var(--mvb-white);
    border-radius: var(--mvb-radius);
    box-shadow: var(--mvb-shadow-sm);
    overflow: hidden;
}

.mvb-faq-question {
    padding: 16px 20px;
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: var(--mvb-text);
    transition: background 0.2s;
}

.mvb-faq-question:hover {
    background: var(--mvb-bg);
}

.mvb-faq-question::-webkit-details-marker {
    display: none;
}

.mvb-faq-question::after {
    content: "+";
    font-size: 1.3rem;
    font-weight: 400;
    color: var(--mvb-text-muted);
    transition: transform 0.2s;
    flex-shrink: 0;
    margin-left: 12px;
}

.mvb-faq-item[open] .mvb-faq-question::after {
    content: "−";
}

.mvb-faq-answer {
    padding: 0 20px 16px;
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
    line-height: 1.6;
    margin: 0;
}

/* --- Footer --- */
.mvb-footer {
    background: var(--mvb-white);
    border-top: 1px solid var(--mvb-border);
    padding: 24px 0;
    text-align: center;
}

.mvb-footer-text {
    font-size: 0.9rem;
    color: var(--mvb-text-muted);
    margin: 0 0 4px;
}

.mvb-footer-disclaimer {
    font-size: 0.8rem;
    color: #94a3b8;
    margin: 0;
}

/* --- Error Page --- */
.mvb-error-page {
    text-align: center;
    padding: 60px 20px;
}

.mvb-error-page-text {
    font-size: 1.1rem;
    color: var(--mvb-text-muted);
    margin: 0 0 24px;
}

/* ============================================================
   Responsive Design
   ============================================================ */

@media (max-width: 768px) {
    .mvb-header {
        padding: 28px 0 24px;
    }

    .mvb-title {
        font-size: 1.5rem;
    }

    .mvb-subtitle {
        font-size: 0.95rem;
    }

    .mvb-main {
        padding: 24px 0 36px;
    }

    .mvb-section {
        margin-bottom: 28px;
    }

    .mvb-action-buttons {
        grid-template-columns: 1fr;
    }

    .mvb-output-grid {
        grid-template-columns: 1fr;
    }

    .mvb-steps-grid {
        grid-template-columns: 1fr;
    }

    .mvb-features-grid {
        grid-template-columns: 1fr;
    }

    .mvb-upload-area {
        padding: 30px 16px;
    }

    .mvb-volume-control {
        padding: 18px;
    }

    .mvb-action-card {
        padding: 20px;
    }
}

@media (min-width: 769px) and (max-width: 1024px) {
    .mvb-features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .mvb-steps-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* Reduce motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
    .mvb-btn,
    .mvb-step-card,
    .mvb-feature-card,
    .mvb-upload-area,
    .mvb-volume-slider::-webkit-slider-thumb {
        transition: none;
    }

    .mvb-btn.mvb-loading .mvb-btn-loading {
        animation: none;
    }
}