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

:root {
    --bg: #0a0a0a;
    --bg-elevated: #111;
    --bg-hover: #1a1a1a;
    --green: #7aff6e;
    --green-dim: #4a9c42;
    --green-glow: rgba(122, 255, 110, 0.15);
    --text: #e8e8e8;
    --text-dim: #666;
    --border: #222;
}

body {
    font-family: 'IBM Plex Mono', monospace;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 20px;
    background-image:
        radial-gradient(circle at center, #151515 1px, transparent 1px);
    background-size: 24px 24px;
}

.container {
    width: 100%;
    max-width: 520px;
    min-width: 280px;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1.logo {
    font-family: 'Instrument Serif', serif;
    font-size: 4.5rem;
    font-weight: 400;
    color: var(--text);
    letter-spacing: -2px;
    line-height: 1;
    margin-bottom: 12px;
    position: relative;
    display: inline-block;
    cursor: default;
    transition: opacity 0.15s ease, color 0.3s ease, text-shadow 0.3s ease;
}

header h1.logo.expanded {
    font-size: 2.8rem;
    color: var(--green);
    text-shadow: 0 0 20px var(--green-glow);
    letter-spacing: 0px;
}

header h1.logo::after {
    content: '';
    position: absolute;
    bottom: 5px;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--green);
    opacity: 0.6;
    border-radius: 2px;
    transition: opacity 0.3s ease;
}

header h1.logo.expanded::after {
    opacity: 1;
}

.tagline {
    color: var(--text-dim);
    font-size: 0.85rem;
}

.mode-selector {
    display: flex;
    gap: 0;
    margin-bottom: 32px;
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    background: var(--bg-elevated);
}

.mode-btn {
    flex: 1;
    padding: 14px;
    border: none;
    background: transparent;
    color: var(--text-dim);
    font-family: inherit;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.2s ease;
    position: relative;
}

.mode-btn:first-child {
    border-right: 1px solid var(--border);
}

.mode-btn:hover {
    color: var(--text);
    background: var(--bg-hover);
}

.mode-btn.active {
    background: var(--green);
    color: #000;
    font-weight: 500;
}

.view {
    display: none;
    animation: fadeIn 0.3s ease;
}

.view.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.hidden {
    display: none !important;
}

/* Drop Zone */
.drop-zone {
    border: 2px dashed var(--border);
    border-radius: 12px;
    padding: 48px 24px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    background: var(--bg-elevated);
    position: relative;
    overflow: hidden;
}

.drop-zone::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at center, var(--green-glow) 0%, transparent 70%);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.drop-zone:hover::before,
.drop-zone.drag-over::before {
    opacity: 1;
}

.drop-zone:hover,
.drop-zone.drag-over {
    border-color: var(--green);
    transform: scale(1.01);
}

.drop-zone-content {
    position: relative;
    z-index: 1;
}

.drop-icon {
    font-size: 2.5rem;
    display: block;
    margin-bottom: 16px;
    color: var(--text-dim);
    transition: all 0.2s ease;
}

.drop-zone:hover .drop-icon,
.drop-zone.drag-over .drop-icon {
    color: var(--green);
    transform: scale(1.1);
}

.drop-zone-content p {
    color: var(--text-dim);
    font-size: 0.9rem;
}

.drop-zone-hint {
    display: block;
    margin-top: 10px;
    color: var(--text-dim);
    font-size: 0.78rem;
    line-height: 1.5;
}

.link-btn {
    background: none;
    border: none;
    color: var(--green);
    cursor: pointer;
    font-family: inherit;
    font-size: inherit;
    text-decoration: underline;
    text-underline-offset: 3px;
    transition: color 0.2s;
}

.link-btn:hover {
    color: var(--text);
}

/* File Info */
.file-info {
    background: var(--bg-elevated);
    padding: 16px 20px;
    border-radius: 10px;
    border: 1px solid var(--border);
    margin-top: 16px;
}

.file-details {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.file-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
}

.file-name {
    font-size: 0.9rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    max-width: 70%;
    color: var(--text);
}

.file-size {
    color: var(--green);
    font-size: 0.85rem;
    font-weight: 500;
}

.file-subtext {
    color: var(--text-dim);
    font-size: 0.78rem;
    line-height: 1.45;
    word-break: break-word;
}

/* Code Section */
.code-section {
    text-align: center;
    margin-top: 32px;
}

.code-section > p:first-child {
    color: var(--text-dim);
    margin-bottom: 16px;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.code-display {
    display: inline-flex;
    align-items: center;
    gap: 16px;
    background: var(--bg-elevated);
    padding: 20px 28px;
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: 0 0 30px var(--green-glow);
}

#share-code {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 2rem;
    font-weight: 500;
    letter-spacing: 8px;
    color: var(--green);
    text-shadow: 0 0 20px var(--green-glow);
}

.copy-btn {
    background: var(--bg-hover);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text-dim);
    cursor: pointer;
    padding: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}

.copy-btn:hover {
    color: var(--green);
    border-color: var(--green);
    background: rgba(122, 255, 110, 0.1);
}

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

.status {
    margin-top: 24px;
    color: var(--text-dim);
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.status::before {
    content: '';
    width: 6px;
    height: 6px;
    background: var(--green);
    border-radius: 50%;
    animation: pulse 1.5s ease infinite;
}

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

/* Input Section (Receiver) */
.input-section {
    text-align: center;
    padding: 20px 0;
}

.input-section label {
    display: block;
    color: var(--text-dim);
    margin-bottom: 20px;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.code-input-wrapper {
    display: flex;
    gap: 12px;
    justify-content: center;
}

#code-input {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 1.5rem;
    text-align: center;
    letter-spacing: 8px;
    text-transform: uppercase;
    width: 200px;
    padding: 14px 16px;
    border: 2px solid var(--border);
    border-radius: 10px;
    background: var(--bg-elevated);
    color: var(--text);
    outline: none;
    transition: all 0.2s ease;
}

#code-input:focus {
    border-color: var(--green);
    box-shadow: 0 0 20px var(--green-glow);
}

#code-input::placeholder {
    color: #333;
    letter-spacing: 8px;
}

.primary-btn {
    padding: 14px 28px;
    background: var(--green);
    border: none;
    border-radius: 10px;
    color: #000;
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.primary-btn:hover {
    background: #8aff7e;
    transform: translateY(-1px);
    box-shadow: 0 4px 20px var(--green-glow);
}

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

.primary-btn:disabled {
    background: var(--border);
    color: var(--text-dim);
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

/* Connecting */
.connecting-section {
    text-align: center;
    padding: 48px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--green);
    border-radius: 50%;
    margin: 0 auto 20px;
    animation: spin 0.8s linear infinite;
}

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

.connecting-section p {
    color: var(--text-dim);
    font-size: 0.9rem;
}

/* Progress Section */
.progress-section {
    margin-top: 32px;
    background: var(--bg-elevated);
    padding: 24px;
    border-radius: 12px;
    border: 1px solid var(--border);
}

.progress-bar {
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--green-dim), var(--green));
    width: 0%;
    transition: width 0.15s ease;
    box-shadow: 0 0 10px var(--green-glow);
}

.progress-stats {
    display: flex;
    justify-content: space-between;
    margin-top: 16px;
    font-size: 0.8rem;
    color: var(--text-dim);
}

.progress-percent {
    color: var(--green);
    font-weight: 500;
    font-size: 0.9rem;
}

/* Complete Section */
.complete-section {
    text-align: center;
    padding: 48px;
}

.complete-icon {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 64px;
    height: 64px;
    background: rgba(122, 255, 110, 0.15);
    color: var(--green);
    font-size: 1.8rem;
    border-radius: 50%;
    margin-bottom: 20px;
    box-shadow: 0 0 30px var(--green-glow);
}

.complete-section p {
    color: var(--text);
    font-size: 1rem;
    margin-bottom: 28px;
}

/* Error Section */
.error-section {
    text-align: center;
    padding: 48px;
}

.error-icon {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 64px;
    height: 64px;
    background: rgba(255, 100, 100, 0.15);
    color: #ff6464;
    font-size: 1.8rem;
    border-radius: 50%;
    margin-bottom: 20px;
}

.error-message {
    color: #ff6464;
    font-size: 0.9rem;
    margin-bottom: 28px;
}

/* Features Section */
.features {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 16px;
    margin-top: 48px;
    padding-top: 32px;
    border-top: 1px solid var(--border);
}

.feature {
    text-align: center;
}

.feature-divider {
    color: var(--border);
    font-size: 0.8rem;
}

.feature-text {
    font-size: 0.75rem;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Watermark */
.watermark {
    position: fixed;
    bottom: 20px;
    left: 0;
    right: 0;
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-dim);
}

.watermark a {
    color: var(--green);
    text-decoration: none;
    transition: color 0.2s;
}

.watermark a:hover {
    color: var(--text);
    text-decoration: underline;
}

/* Responsive */
@media (max-width: 600px) {
    body {
        padding: 16px;
    }

    header h1.logo {
        font-size: 3rem;
    }

    .tagline {
        font-size: 0.8rem;
    }

    .drop-zone {
        padding: 40px 16px;
    }

    .code-display {
        padding: 16px 20px;
    }

    #share-code {
        font-size: 1.5rem;
        letter-spacing: 6px;
    }

    .code-input-wrapper {
        flex-direction: column;
        align-items: center;
        gap: 16px;
    }

    #code-input {
        width: 100%;
        max-width: 220px;
        font-size: 1.3rem;
        letter-spacing: 6px;
    }

    .primary-btn {
        width: 100%;
        max-width: 220px;
    }

    .progress-stats {
        flex-wrap: wrap;
        gap: 8px;
        justify-content: center;
    }

    .file-name {
        max-width: 100%;
    }

    .file-header {
        width: 100%;
        flex-direction: column;
        align-items: flex-start;
        gap: 4px;
    }

    .features {
        gap: 20px;
    }

    .feature-text {
        font-size: 0.7rem;
    }
}

@media (max-width: 360px) {
    header h1 {
        font-size: 2.5rem;
    }

    .mode-btn {
        padding: 12px;
        font-size: 0.85rem;
    }

    .features {
        flex-direction: column;
        gap: 16px;
    }
}