:root {
    --bg: #0d0f14;
    --surface: #161920;
    --surface2: #1e2230;
    --border: #2a2f42;
    --accent: #4fffb0;
    --accent-dim: #1a3d2e;
    --accent-glow: rgba(79, 255, 176, 0.15);
    --text: #e8ecf4;
    --text-dim: #6b7394;
    --red: #ff4f6a;
    --red-dim: #3d1a22;
}

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

body {
    font-family: 'IBM Plex Mono', monospace;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 40px 20px 80px;
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(var(--border) 1px, transparent 1px),
        linear-gradient(90deg, var(--border) 1px, transparent 1px);
    background-size: 48px 48px;
    opacity: 0.3;
    pointer-events: none;
}

.wrapper {
    position: relative;
    width: 100%;
    max-width: 520px;
    z-index: 1;
}

.header {
    text-align: center;
    margin-bottom: 48px;
}

.logo {
    font-family: 'Syne', sans-serif;
    font-size: 2.2rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--text);
}

.logo span { color: var(--accent); }

.subtitle {
    font-size: 0.72rem;
    color: var(--text-dim);
    letter-spacing: 0.18em;
    text-transform: uppercase;
    margin-top: 6px;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 32px;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent), transparent);
    opacity: 0.6;
}

.security-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: var(--accent-dim);
    border: 1px solid rgba(79,255,176,0.3);
    border-radius: 20px;
    padding: 4px 12px;
    font-size: 0.65rem;
    color: var(--accent);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: 28px;
}

.security-badge .dot {
    width: 6px;
    height: 6px;
    background: var(--accent);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.3; }
}

.field { margin-bottom: 20px; }

.field label {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.68rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-bottom: 8px;
}

.input-wrap { position: relative; }

.field input {
    width: 100%;
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 13px 16px;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.9rem;
    color: var(--text);
    transition: border-color 0.2s, box-shadow 0.2s;
    outline: none;
    -webkit-appearance: none;
}

.field input::placeholder { color: #3a3f58; }

.field input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.field input.has-toggle { padding-right: 46px; }

.toggle-vis {
    position: absolute;
    right: 14px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-dim);
    cursor: pointer;
    padding: 2px;
    font-size: 1rem;
    line-height: 1;
    transition: color 0.2s;
}
.toggle-vis:hover { color: var(--text); }

/* ── 알고리즘 선택기 ── */
.algo-select-wrap {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.algo-select {
    width: 100%;
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 13px 16px;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.85rem;
    color: var(--text);
    outline: none;
    cursor: pointer;
    transition: border-color 0.2s, box-shadow 0.2s;
    -webkit-appearance: none;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%236b7394' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    padding-right: 36px;
}

.algo-select:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.algo-select option {
    background: var(--surface2);
    color: var(--text);
}

/* ── 보안 레벨 바 ── */
.security-level {
    display: flex;
    gap: 4px;
}

.security-level .sec-seg {
    flex: 1;
    height: 3px;
    border-radius: 2px;
    transition: background 0.3s;
    background: var(--border);
}

.strength-bar {
    display: flex;
    gap: 4px;
    margin-top: 8px;
}
.strength-bar .seg {
    flex: 1;
    height: 3px;
    background: var(--border);
    border-radius: 2px;
    transition: background 0.3s;
}
.strength-bar.s1 .seg:nth-child(1)      { background: var(--red); }
.strength-bar.s2 .seg:nth-child(-n+2)   { background: #ff9f4f; }
.strength-bar.s3 .seg:nth-child(-n+3)   { background: #ffe04f; }
.strength-bar.s4 .seg                   { background: var(--accent); }

.strength-label {
    font-size: 0.6rem;
    color: var(--text-dim);
    margin-top: 4px;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.kdf-info {
    display: flex;
    align-items: center;
    gap: 8px;
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 14px;
    font-size: 0.68rem;
    color: var(--text-dim);
    margin-bottom: 24px;
}
.kdf-info .icon { font-size: 1rem; }
.kdf-info strong { color: var(--accent); }

.btn-primary {
    width: 100%;
    padding: 14px;
    background: var(--accent);
    color: #0a1a12;
    border: none;
    border-radius: 10px;
    font-family: 'Syne', sans-serif;
    font-size: 0.95rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    cursor: pointer;
    transition: opacity 0.2s, transform 0.1s;
    position: relative;
    overflow: hidden;
}
.btn-primary:hover:not(:disabled) { opacity: 0.9; }
.btn-primary:active:not(:disabled) { transform: scale(0.98); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-secondary {
    flex: 1;
    padding: 11px 16px;
    background: var(--surface2);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: 10px;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.8rem;
    cursor: pointer;
    transition: border-color 0.2s, background 0.2s;
}
.btn-secondary:hover { border-color: var(--accent); background: var(--accent-dim); }

.spinner-wrap {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: 14px;
    padding: 20px 0 4px;
}
.spinner-wrap.active { display: flex; }

.spinner {
    width: 36px;
    height: 36px;
    border: 3px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.spinner-label {
    font-size: 0.72rem;
    color: var(--text-dim);
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.kdf-progress {
    font-size: 0.68rem;
    color: var(--accent);
    margin-top: -6px;
}

.result-card {
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    margin-top: 24px;
}

.result-label {
    font-size: 0.65rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-bottom: 10px;
}

.result-url {
    font-size: 0.78rem;
    color: var(--accent);
    word-break: break-all;
    line-height: 1.6;
    padding: 12px;
    background: var(--bg);
    border-radius: 8px;
    border: 1px solid var(--accent-dim);
}

.result-url a {
    color: inherit;
    text-decoration: none;
}
.result-url a:hover { text-decoration: underline; }

.qr-wrap {
    display: flex;
    justify-content: center;
    margin: 20px 0;
}

#qrcode {
    border-radius: 10px;
    border: 6px solid white;
}

.btn-row {
    display: flex;
    gap: 10px;
    margin-top: 16px;
}

.decrypt-preview {
    margin-top: 24px;
    padding: 16px;
    background: var(--accent-dim);
    border: 1px solid rgba(79,255,176,0.25);
    border-radius: 12px;
}

.decrypt-preview .preview-label {
    font-size: 0.65rem;
    color: var(--accent);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    margin-bottom: 8px;
}

.decrypt-preview .preview-url { display: none; }

@keyframes shake {
    0%,100% { transform: translateX(0); }
    20%      { transform: translateX(-8px); }
    40%      { transform: translateX(8px); }
    60%      { transform: translateX(-6px); }
    80%      { transform: translateX(6px); }
}
.shake { animation: shake 0.4s ease; }

.field input.error {
    border-color: var(--red);
    box-shadow: 0 0 0 3px rgba(255,79,106,0.15);
}

.divider {
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 20px 0;
    color: var(--text-dim);
    font-size: 0.68rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}
.divider::before, .divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
}

.footer {
    margin-top: 32px;
    font-size: 0.65rem;
    color: var(--text-dim);
    text-align: center;
    line-height: 1.8;
    letter-spacing: 0.06em;
}
.footer strong { color: var(--accent); }

@keyframes fadeUp {
    from { opacity: 0; transform: translateY(12px); }
    to   { opacity: 1; transform: translateY(0); }
}
.card { animation: fadeUp 0.4s ease; }

.copy-feedback {
    display: inline-block;
    transition: transform 0.1s;
}