:root {
    --bg-base: #08080c;
    --bg-raised: #0e0e14;
    --bg-surface: #14141c;
    --bg-hover: #1a1a24;
    --border: #22222e;
    --border-light: #2e2e3c;
    --text: #e4e4ea;
    --text-sec: #8888a0;
    --text-muted: #555568;
    --accent: #c8ff00;
    --accent-dim: #a0cc00;
    --accent-bg: rgba(200, 255, 0, 0.06);
    --error: #ff4757;
    --error-bg: rgba(255, 71, 87, 0.06);
    --success: #2ed573;
    --font-sans: 'Space Grotesk', system-ui, -apple-system, 'Segoe UI', sans-serif;
    --font-mono: 'Cascadia Code', 'Fira Code', 'Consolas', 'Monaco', monospace;
    --speed: 200ms;
}

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-base);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-image: radial-gradient(circle, #16161e 1px, transparent 1px);
    background-size: 24px 24px;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--accent);
    z-index: 100;
}

::selection {
    background: rgba(200, 255, 0, 0.2);
    color: var(--text);
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: opacity var(--speed);
}

a:hover {
    opacity: 0.8;
}

::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: var(--bg-base);
}

::-webkit-scrollbar-thumb {
    background: var(--border);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-light);
}

/* ── Header ── */

.header {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border);
    backdrop-filter: blur(8px);
    position: sticky;
    top: 2px;
    z-index: 50;
    background: rgba(8, 8, 12, 0.85);
}

.header-inner {
    max-width: 680px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-family: var(--font-mono);
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    user-select: none;
}

.logo-slash {
    color: var(--accent);
    margin-right: 1px;
}

.header-badge {
    font-family: var(--font-mono);
    font-size: 0.6rem;
    letter-spacing: 0.15em;
    color: var(--text-muted);
    border: 1px solid var(--border);
    padding: 2px 10px;
}

/* ── Main ── */

.main {
    flex: 1;
    max-width: 680px;
    width: 100%;
    margin: 0 auto;
    padding: 0 24px 80px;
}

/* ── Hero ── */

.hero {
    padding: 52px 0 44px;
}

.hero-tag {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--accent);
    letter-spacing: 0.12em;
    margin-bottom: 14px;
}

.hero h1 {
    font-size: 1.85rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    line-height: 1.2;
    margin-bottom: 10px;
}

.hero-desc {
    color: var(--text-sec);
    font-size: 0.92rem;
    line-height: 1.7;
}

/* ── Switcher ── */

.switcher {
    display: flex;
    position: relative;
    margin-bottom: 44px;
    border: 1px solid var(--border);
    background: var(--bg-raised);
    overflow: hidden;
}

.switcher-btn {
    flex: 1;
    padding: 13px 24px;
    background: none;
    border: none;
    color: var(--text-muted);
    font-family: var(--font-sans);
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    cursor: pointer;
    position: relative;
    z-index: 2;
    transition: color 0.3s;
    text-align: center;
}

.switcher-btn.active {
    color: var(--bg-base);
}

.switcher-indicator {
    position: absolute;
    top: 3px;
    left: 3px;
    width: calc(50% - 3px);
    height: calc(100% - 6px);
    background: var(--accent);
    z-index: 1;
    transition: transform 0.35s cubic-bezier(0.4, 0, 0.15, 1);
}

/* ── Panels ── */

.panel {
    display: none;
}

.panel.active {
    display: block;
    animation: panelIn 0.35s ease;
}

@keyframes panelIn {
    from { opacity: 0; transform: translateY(10px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ── Steps (tree-branch layout) ── */

.steps-container {
    position: relative;
}

.step {
    display: flex;
    gap: 20px;
    opacity: 0.3;
    transition: opacity 0.4s;
    pointer-events: none;
}

.step.active {
    opacity: 1;
    pointer-events: all;
}

.step-marker {
    display: flex;
    flex-direction: column;
    align-items: center;
    flex-shrink: 0;
    width: 36px;
}

.step-num {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    font-weight: 700;
    color: var(--text-muted);
    letter-spacing: 0.04em;
    line-height: 1;
    padding: 3px 0;
    transition: color 0.3s;
}

.step.active .step-num {
    color: var(--accent);
}

.step-line {
    flex: 1;
    width: 1px;
    min-height: 24px;
    margin-top: 10px;
    background: var(--border);
    transition: background 0.3s;
}

.step.active .step-line {
    background: linear-gradient(to bottom, var(--accent) 0%, var(--border) 100%);
}

.step-body {
    flex: 1;
    padding-bottom: 36px;
    min-width: 0;
}

.step-title {
    font-size: 0.95rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: 14px;
}

.step-desc {
    color: var(--text-sec);
    font-size: 0.84rem;
    line-height: 1.65;
    margin-bottom: 14px;
}

/* ── Form Elements ── */

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-size: 0.72rem;
    font-weight: 500;
    color: var(--text-sec);
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-bottom: 8px;
}

.input-wrap {
    position: relative;
}

.input-wrap input {
    width: 100%;
    padding: 10px 0;
    background: transparent;
    border: none;
    border-bottom: 1px solid var(--border);
    color: var(--text);
    font-family: var(--font-mono);
    font-size: 0.82rem;
    outline: none;
    transition: border-color 0.3s;
}

.input-wrap input:focus {
    border-bottom-color: var(--accent);
}

.input-wrap input::placeholder {
    color: var(--text-muted);
    font-family: var(--font-mono);
}

.input-wrap input.input-error {
    border-bottom-color: var(--error);
}

/* ── Buttons ── */

.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 10px 22px;
    border: none;
    font-family: var(--font-sans);
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    cursor: pointer;
    transition: all var(--speed);
    position: relative;
    overflow: hidden;
}

.btn-accent {
    background: var(--accent);
    color: var(--bg-base);
}

.btn-accent:hover:not(:disabled) {
    background: var(--accent-dim);
    transform: translateY(-1px);
}

.btn-accent:active:not(:disabled) {
    transform: translateY(0);
}

.btn-accent:disabled {
    opacity: 0.25;
    cursor: not-allowed;
    transform: none;
}

.btn-icon {
    font-size: 1.05rem;
    line-height: 1;
    transition: transform var(--speed);
}

.btn:hover:not(:disabled) .btn-icon {
    transform: translateX(2px);
}

.btn.loading .btn-text,
.btn.loading .btn-icon {
    visibility: hidden;
}

.btn.loading::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    border: 2px solid transparent;
    border-top-color: var(--bg-base);
    border-right-color: var(--bg-base);
    border-radius: 50%;
    animation: spin 0.5s linear infinite;
}

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

/* ── URL Display Box ── */

.url-box {
    display: flex;
    align-items: center;
    gap: 0;
    background: var(--bg-base);
    border: 1px solid var(--border);
    margin-bottom: 14px;
    overflow: hidden;
}

.url-text {
    flex: 1;
    padding: 10px 14px;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--accent);
    word-break: break-all;
    user-select: all;
    line-height: 1.5;
    min-height: 38px;
    display: flex;
    align-items: center;
}

.btn-copy {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 100%;
    min-height: 38px;
    background: transparent;
    border: none;
    border-left: 1px solid var(--border);
    color: var(--text-muted);
    cursor: pointer;
    flex-shrink: 0;
    transition: all var(--speed);
}

.btn-copy:hover {
    background: var(--bg-hover);
    color: var(--accent);
}

.btn-copy.copied {
    color: var(--success);
}

/* ── Step Hint ── */

.step-hint {
    display: flex;
    gap: 10px;
    align-items: flex-start;
    padding: 12px 14px;
    background: var(--accent-bg);
    border-left: 2px solid var(--accent);
    font-size: 0.8rem;
    color: var(--text-sec);
    line-height: 1.6;
    margin-top: 16px;
}

.hint-icon {
    color: var(--accent);
    font-size: 0.85rem;
    flex-shrink: 0;
    line-height: 1.6;
}

/* ── Checkbox ── */

.checkbox-wrap {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.8rem;
    color: var(--text-sec);
    cursor: pointer;
    margin-top: 14px;
    user-select: none;
}

.checkbox-wrap input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    border: 1px solid var(--border-light);
    background: transparent;
    cursor: pointer;
    position: relative;
    flex-shrink: 0;
    transition: all var(--speed);
}

.checkbox-wrap input[type="checkbox"]:checked {
    background: var(--accent);
    border-color: var(--accent);
}

.checkbox-wrap input[type="checkbox"]:checked::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: var(--bg-base);
    font-size: 0.65rem;
    font-weight: 800;
}

/* ── Results ── */

.results-section {
    margin-top: 8px;
    border: 1px solid var(--border);
    background: var(--bg-raised);
    animation: panelIn 0.4s ease;
}

.results-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 20px;
    border-bottom: 1px solid var(--border);
}

.results-tag {
    font-family: var(--font-mono);
    font-size: 0.6rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    color: var(--accent);
    border: 1px solid rgba(200, 255, 0, 0.3);
    padding: 2px 8px;
}

.results-header h3 {
    font-size: 0.88rem;
    font-weight: 600;
}

.result-item {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 14px 20px;
    border-bottom: 1px solid var(--border);
    transition: background 0.15s;
}

.result-item:last-child {
    border-bottom: none;
}

.result-item:hover {
    background: var(--bg-hover);
}

.result-type {
    flex-shrink: 0;
}

.type-badge {
    font-family: var(--font-mono);
    font-size: 0.62rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 3px 8px;
    border: 1px solid;
    white-space: nowrap;
}

.type-user,
.type-private {
    color: #6ee7b7;
    border-color: rgba(110, 231, 183, 0.25);
}

.type-group,
.type-supergroup {
    color: #93c5fd;
    border-color: rgba(147, 197, 253, 0.25);
}

.type-channel {
    color: #fbbf24;
    border-color: rgba(251, 191, 36, 0.25);
}

.type-room {
    color: #c4b5fd;
    border-color: rgba(196, 181, 253, 0.25);
}

.result-info {
    flex: 1;
    min-width: 0;
}

.result-name {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 3px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.result-id {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--text-sec);
    word-break: break-all;
    line-height: 1.4;
}

.btn-copy-id {
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 6px 14px;
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-sec);
    font-family: var(--font-sans);
    font-size: 0.7rem;
    font-weight: 500;
    cursor: pointer;
    flex-shrink: 0;
    transition: all var(--speed);
    letter-spacing: 0.02em;
}

.btn-copy-id:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.btn-copy-id.copied {
    border-color: var(--success);
    color: var(--success);
}

.results-empty {
    padding: 32px 20px;
    text-align: center;
}

.results-empty p {
    color: var(--text-sec);
    font-size: 0.88rem;
    margin-bottom: 6px;
}

.results-empty .hint {
    color: var(--text-muted);
    font-size: 0.78rem;
}

/* ── Footer ── */

.footer {
    padding: 20px 24px;
    border-top: 1px solid var(--border);
    background: var(--bg-raised);
}

.privacy {
    max-width: 680px;
    margin: 0 auto;
    display: flex;
    gap: 12px;
    align-items: flex-start;
}

.privacy-icon {
    color: var(--accent);
    flex-shrink: 0;
    margin-top: 1px;
    opacity: 0.7;
}

.privacy-text {
    font-size: 0.76rem;
    color: var(--text-muted);
    line-height: 1.65;
}

.privacy-text strong {
    color: var(--text-sec);
    display: block;
    margin-bottom: 2px;
    font-size: 0.72rem;
    letter-spacing: 0.04em;
}

.footer-credits {
    max-width: 680px;
    margin: 0 auto;
    margin-top: 18px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
    font-size: 0.72rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
}

.footer-copyright {
    letter-spacing: 0.02em;
}

.footer-divider {
    opacity: 0.5;
}

.footer-link {
    color: var(--text-sec);
    transition: color var(--speed);
}

.footer-link:hover {
    color: var(--accent);
}

/* ── Toast ── */

.toast {
    position: fixed;
    top: 24px;
    right: 24px;
    padding: 11px 22px;
    font-size: 0.8rem;
    font-weight: 500;
    font-family: var(--font-sans);
    border-left: 3px solid var(--border);
    background: var(--bg-surface);
    color: var(--text);
    transform: translateX(calc(100% + 30px));
    transition: transform 0.35s cubic-bezier(0.4, 0, 0.15, 1);
    z-index: 1000;
    max-width: 320px;
    pointer-events: none;
}

.toast-show {
    transform: translateX(0);
}

.toast-success {
    border-left-color: var(--success);
}

.toast-error {
    border-left-color: var(--error);
}

/* ── Error Banner ── */

.error-banner {
    padding: 12px 14px;
    background: var(--error-bg);
    border-left: 2px solid var(--error);
    font-size: 0.8rem;
    color: var(--error);
    line-height: 1.5;
    margin-top: 14px;
    display: none;
}

.error-banner.show {
    display: block;
    animation: panelIn 0.25s ease;
}

/* ── Responsive ── */

@media (max-width: 640px) {
    .hero {
        padding: 36px 0 32px;
    }

    .hero h1 {
        font-size: 1.4rem;
    }

    .hero-desc br {
        display: none;
    }

    .switcher {
        margin-bottom: 32px;
    }

    .step {
        gap: 14px;
    }

    .step-marker {
        width: 28px;
    }

    .step-num {
        font-size: 0.7rem;
    }

    .step-body {
        padding-bottom: 28px;
    }

    .result-item {
        flex-wrap: wrap;
        gap: 10px;
        padding: 12px 16px;
    }

    .result-info {
        width: calc(100% - 90px);
    }

    .btn-copy-id {
        margin-left: auto;
    }

    .url-box {
        flex-direction: column;
    }

    .url-text {
        width: 100%;
        font-size: 0.7rem;
        padding: 10px 12px;
    }

    .btn-copy {
        width: 100%;
        border-left: none;
        border-top: 1px solid var(--border);
        min-height: 36px;
    }

    .toast {
        left: 16px;
        right: 16px;
        max-width: none;
    }
}

@media (max-width: 400px) {
    .main {
        padding: 0 16px 60px;
    }

    .header {
        padding: 14px 16px;
    }
}