:root {
    --bg-container: rgba(20, 20, 20, 0.95);
    --bg-textarea: rgba(10, 10, 10, 0.8);
    --bg-output: rgba(15, 15, 15, 0.9);
    --bg-char-btn: rgba(40, 40, 40, 0.8);
    --bg-char-btn-hover: rgba(60, 60, 60, 0.9);
    --bg-select: rgba(30, 30, 30, 0.9);
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-label: #d0d0d0;
    --text-char-label: #c0c0c0;
    --border-color: rgba(255, 255, 255, 0.1);
    --border-textarea: rgba(255, 255, 255, 0.1);
    --border-output: rgba(100, 200, 100, 0.2);
    --border-char-btn: rgba(255, 255, 255, 0.15);
    --border-select: rgba(255, 255, 255, 0.15);
    --shadow-container: 0 20px 60px rgba(0, 0, 0, 0.5);
    --shadow-char-btn: 0 4px 12px rgba(255, 255, 255, 0.1);
}

[data-theme="light"] {
    --bg-container: rgba(255, 255, 255, 0.95);
    --bg-textarea: rgba(250, 250, 250, 0.9);
    --bg-output: rgba(245, 255, 245, 0.9);
    --bg-char-btn: rgba(240, 240, 240, 0.9);
    --bg-char-btn-hover: rgba(220, 220, 220, 0.95);
    --bg-select: rgba(245, 245, 245, 0.9);
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --text-label: #333333;
    --text-char-label: #555555;
    --border-color: rgba(0, 0, 0, 0.1);
    --border-textarea: rgba(0, 0, 0, 0.15);
    --border-output: rgba(50, 150, 50, 0.3);
    --border-char-btn: rgba(0, 0, 0, 0.2);
    --border-select: rgba(0, 0, 0, 0.2);
    --shadow-container: 0 20px 60px rgba(0, 0, 0, 0.15);
    --shadow-char-btn: 0 4px 12px rgba(0, 0, 0, 0.1);
    --body-bg-color: #ffffff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    transition: background 0.3s ease;
}

html[data-theme="dark"] {
    background: linear-gradient(135deg, #0a0a0a 0%, #1a1a1a 100%);
}

html[data-theme="light"] {
    background: linear-gradient(135deg, #f5f5f5 0%, #e8e8e8 100%);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--body-bg-color);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 20px;
    transition: color 0.3s ease, background 0.3s ease;
    position: relative;
}

.container {
    width: 100%;
    max-width: 900px;
    background: var(--bg-container);
    border-radius: 20px;
    padding: 40px;
    box-shadow: var(--shadow-container);
    border: 1px solid var(--border-color);
    transition: background 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

/* ── Language switcher ── */
.lang-switcher {
    position: absolute;
    top: 20px;
    left: 20px;
    display: flex;
    gap: 5px;
    background: var(--bg-char-btn);
    border: 1px solid var(--border-char-btn);
    border-radius: 50px;
    padding: 5px;
    z-index: 100;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.lang-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 5px 12px;
    cursor: pointer;
    border-radius: 50px;
    font-size: 13px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.lang-btn:hover {
    color: var(--text-primary);
    background: var(--bg-char-btn-hover);
}

.lang-btn.active {
    background: var(--bg-container);
    color: var(--text-primary);
    box-shadow: 0 1px 4px rgba(0,0,0,0.1);
    font-weight: 600;
}

/* ── Theme toggle ── */
.theme-toggle {
    position: absolute;
    top: 20px;
    right: 20px;
    background: var(--bg-char-btn);
    border: 1px solid var(--border-char-btn);
    border-radius: 50px;
    padding: 10px 20px;
    cursor: pointer;
    font-size: 14px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
    z-index: 100;
}

.theme-toggle:hover {
    background: var(--bg-char-btn-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-char-btn);
}

/* ── Logo header ── */
.logo-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 30px;
    margin-bottom: 30px;
    padding: 20px 0;
    margin-top: 40px;
}

.logo-text {
    font-size: 2.2em;
    font-weight: 300;
    letter-spacing: 3px;
    color: var(--text-primary);
    text-transform: uppercase;
    min-width: 120px;
    text-align: center;
    transition: color 0.3s ease;
}

.logo-container {
    width: 120px;
    height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.logo-image {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

/* ── Intro text ── */
.main-subtitle {
    text-align: center;
    margin-bottom: 30px;
    color: var(--text-secondary);
    font-size: 1.1em;
    font-weight: 400;
    transition: color 0.3s ease;
}

.intro-block {
    margin-bottom: 25px;
    line-height: 1.55;
    color: var(--text-secondary);
    font-size: 0.95em;
}

.intro-block h2 {
    font-size: 1.15em;
    margin-bottom: 10px;
    color: var(--text-primary);
    font-weight: 600;
}

.intro-block p {
    margin-top: 10px;
}

.intro-block ul {
    margin-top: 10px;
    padding-left: 20px;
}

/* ── Textarea & labels ── */
.input-section {
    margin-bottom: 15px;
    position: relative;
}

.textarea-wrapper {
    position: relative;
}

.field-label {
    display: block;
    margin-bottom: 10px;
    color: var(--text-label);
    font-size: 0.95em;
    font-weight: 500;
    transition: color 0.3s ease;
    cursor: pointer;
}

textarea {
    width: 100%;
    min-height: 200px;
    padding: 20px 50px 20px 20px;
    background: var(--bg-textarea);
    border: 2px solid var(--border-textarea);
    border-radius: 12px;
    color: var(--text-primary);
    font-size: 16px;
    font-family: inherit;
    resize: vertical;
    transition: border-color 0.3s ease, box-shadow 0.3s ease, background 0.3s ease, color 0.3s ease;
}

textarea:focus {
    outline: none;
    border-color: rgba(100, 150, 255, 0.5);
    box-shadow: 0 0 20px rgba(100, 150, 255, 0.2);
}

/* ── Char count ── */
.char-count {
    text-align: right;
    font-size: 0.78em;
    color: var(--text-secondary);
    margin-top: 5px;
    transition: color 0.3s ease;
}

/* ── Clear / copy buttons ── */
.clear-btn, .copy-btn {
    position: absolute;
    top: 15px;
    right: 5px;
    background: transparent;
    border: none;
    cursor: pointer;
    font-size: 25px;
    color: var(--text-secondary);
    padding: 5px;
    border-radius: 50%;
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    opacity: 0.6;
    transform: none;
}

.clear-btn:hover, .copy-btn:hover {
    opacity: 1;
    background: var(--bg-char-btn);
    color: var(--text-primary);
    transform: scale(1.1);
}

.copy-btn img {
    width: 18px;
    height: 18px;
    object-fit: contain;
    transition: opacity 0.3s ease, filter 0.3s ease;
    pointer-events: none;
}

html[data-theme="dark"] .copy-btn img {
    filter: invert(1) brightness(1.2);
    opacity: 0.7;
}

html[data-theme="light"] .copy-btn img {
    filter: brightness(0.6);
    opacity: 0.6;
}

.copy-btn:hover img { opacity: 1; }
html[data-theme="dark"] .copy-btn:hover img { filter: invert(1) brightness(1.5); }
html[data-theme="light"] .copy-btn:hover img { filter: brightness(0.4); }

/* ── Output section ── */
.output-section {
    position: relative;
    margin-top: 30px;
}

.copy-btn { right: 5px; }

.output-textarea {
    background: var(--bg-output);
    border: 2px solid var(--border-output);
    padding: 20px 50px 20px 20px;
    transition: border-color 0.3s ease, box-shadow 0.3s ease, background 0.3s ease;
}

.output-textarea:focus {
    border-color: rgba(100, 200, 100, 0.4);
    box-shadow: 0 0 20px rgba(100, 200, 100, 0.15);
}

/* ── Special chars ── */
.special-chars-section {
    margin-top: 15px;
    margin-bottom: 25px;
    padding: 15px 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.special-chars-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(50px, 1fr));
    gap: 6px;
    max-width: 100%;
    margin: 0 auto;
}

.char-btn {
    background: var(--bg-char-btn);
    color: var(--text-primary);
    border: 1px solid var(--border-char-btn);
    padding: 8px 4px;
    border-radius: 15px;
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.char-btn:hover {
    background: var(--bg-char-btn-hover);
    border-color: var(--border-char-btn);
    transform: translateY(-2px);
    box-shadow: var(--shadow-char-btn);
}

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

.char-cyrillic {
    font-size: 18px;
    font-weight: 600;
}

/* ── Alphabet select ── */
.alphabet-select-section {
    margin-bottom: 25px;
    text-align: center;
}

.alphabet-select {
    width: 100%;
    max-width: 400px;
    padding: 12px 15px;
    font-size: 16px;
    font-weight: 500;
    color: var(--text-primary);
    background-color: var(--bg-select);
    border: 2px solid var(--border-select);
    border-radius: 12px;
    cursor: pointer;
    appearance: none;
    -webkit-appearance: none;
    background-image: linear-gradient(45deg, transparent 50%, var(--text-secondary) 50%),
                      linear-gradient(135deg, var(--text-secondary) 50%, transparent 50%);
    background-position: calc(100% - 20px) calc(1em + 2px), calc(100% - 15px) calc(1em + 2px);
    background-size: 5px 5px, 5px 5px;
    background-repeat: no-repeat;
    transition: all 0.3s ease;
}

.alphabet-select:focus {
    outline: none;
    border-color: rgba(100, 150, 255, 0.5);
    box-shadow: 0 0 20px rgba(100, 150, 255, 0.2);
}

.alphabet-select option {
    background: var(--bg-container);
    color: var(--text-primary);
    padding: 10px;
}

/* ── Translate button ── */
.button-container {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
}

.translate-btn {
    background: linear-gradient(135deg, #4a90e2 0%, #357abd 100%);
    color: white;
    border: none;
    padding: 15px 40px;
    font-size: 18px;
    font-weight: 600;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
    letter-spacing: 1px;
}

.translate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px rgba(74, 144, 226, 0.5);
    background: linear-gradient(135deg, #5aa0f2 0%, #458acd 100%);
}

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

/* ── Toast ── */
.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: var(--bg-container);
    color: var(--text-primary);
    padding: 12px 20px;
    border-radius: 8px;
    box-shadow: var(--shadow-container);
    border: 1px solid var(--border-color);
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.3s ease;
    z-index: 1000;
}

.toast.show {
    opacity: 1;
    transform: translateY(0);
}

/* ── FAQ ── */
.faq-section {
    margin-top: 40px;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
}

.faq-title {
    font-size: 1.5em;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 20px;
    text-align: center;
    transition: color 0.3s ease;
}

.faq-item {
    margin-bottom: 15px;
    background: var(--bg-textarea);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-item:hover {
    border-color: rgba(100, 150, 255, 0.3);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.faq-item.active { border-color: rgba(100, 150, 255, 0.5); }

.faq-question {
    font-size: 1.1em;
    font-weight: 600;
    color: var(--text-primary);
    padding: 15px 20px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: color 0.3s ease, background 0.3s ease;
    user-select: none;
}

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

.faq-question-icon {
    font-size: 1.2em;
    transition: transform 0.3s ease;
    color: var(--text-secondary);
    flex-shrink: 0;
    margin-left: 15px;
}

.faq-item.active .faq-question-icon { transform: rotate(180deg); }

.faq-answer {
    font-size: 0.95em;
    color: var(--text-secondary);
    line-height: 1.6;
    padding: 0 20px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease, color 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 1000px;
    padding: 0 20px 15px 20px;
}

.faq-answer a {
    color: #4a90e2;
    text-decoration: none;
    transition: color 0.3s ease;
}

.faq-answer a:hover {
    color: #5aa0f2;
    text-decoration: underline;
}

.faq-sources {
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

.faq-sources-title {
    font-size: 1em;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 10px;
    transition: color 0.3s ease;
}

.faq-sources-list {
    list-style: none;
    padding: 0;
}

.faq-sources-list li { margin-bottom: 8px; }

.faq-sources-list a {
    color: #4a90e2;
    text-decoration: none;
    transition: color 0.3s ease;
    word-break: break-all;
}

.faq-sources-list a:hover {
    color: #5aa0f2;
    text-decoration: underline;
}

/* ── Footer links ── */
.footer-links {
    text-align: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

.footer-links a {
    display: inline-block;
    width: 32px;
    height: 32px;
    margin: 0 10px;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.footer-links a:hover {
    opacity: 1;
    transform: scale(1.1);
}

.footer-links img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    transition: filter 0.3s ease, opacity 0.3s ease;
}

html[data-theme="dark"] .footer-links img { filter: invert(1) brightness(1.2); opacity: 0.7; }
html[data-theme="light"] .footer-links img { filter: brightness(0.6); opacity: 0.6; }
html[data-theme="dark"] .footer-links a:hover img { filter: invert(1) brightness(1.5); opacity: 1; }
html[data-theme="light"] .footer-links a:hover img { filter: brightness(0.4); opacity: 1; }

/* ── Responsive ── */
@media (max-width: 768px) {
    .container { padding: 25px; }

    .lang-switcher { top: 10px; left: 10px; padding: 4px; gap: 4px; }
    .lang-btn { font-size: 11px; padding: 4px 8px; }

    .theme-toggle { top: 10px; right: 10px; padding: 8px 15px; font-size: 12px; }

    .logo-header { gap: 15px; margin-bottom: 20px; padding: 15px 0; margin-top: 45px; }
    .logo-text { font-size: 1.5em; min-width: 80px; letter-spacing: 2px; }
    .logo-container { width: 80px; height: 80px; }

    .special-chars-grid { grid-template-columns: repeat(auto-fit, minmax(45px, 1fr)); gap: 5px; }
    .char-btn { padding: 6px 3px; font-size: 11px; }
    .char-cyrillic { font-size: 16px; }

    .clear-btn, .copy-btn { width: 25px; height: 25px; font-size: 25px; top: 12px; transform: none; }
    .clear-btn:hover, .copy-btn:hover { transform: scale(1.1); }
    .copy-btn img { width: 16px; height: 16px; }

    .faq-section { margin-top: 30px; padding-top: 20px; }
    .faq-title { font-size: 1.3em; margin-bottom: 15px; }
    .faq-item { margin-bottom: 12px; }
    .faq-question { font-size: 1em; padding: 12px 15px; }
    .faq-answer { padding: 0 15px; font-size: 0.9em; }
    .faq-item.active .faq-answer { padding: 0 15px 12px 15px; }
}