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

body {
    font-family:
        -apple-system, BlinkMacSystemFont, "Segoe UI",
        "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 40px 30px;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}

.header-content > div {
    text-align: left;
}

header h1 {
    font-size: 2rem;
    margin-bottom: 10px;
}

header p {
    font-size: 1rem;
    opacity: 0.9;
}

.logout-btn {
    padding: 10px 20px;
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid white;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition:
        background 0.3s,
        transform 0.2s;
    white-space: nowrap;
}

.logout-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

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

main {
    padding: 40px 30px;
}

section {
    margin-bottom: 40px;
}

section:last-child {
    margin-bottom: 0;
}

h2 {
    font-size: 1.5rem;
    color: #333;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid #667eea;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    font-weight: 600;
    color: #555;
    margin-bottom: 8px;
}

textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    font-family: "Courier New", monospace;
    resize: vertical;
    transition: border-color 0.3s;
}

textarea:focus {
    outline: none;
    border-color: #667eea;
}

.button-group {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.paste-btn,
.decrypt-btn {
    padding: 15px;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition:
        transform 0.2s,
        box-shadow 0.2s;
}

.paste-btn {
    flex: 0 0 auto;
    background: #f8f9fa;
    color: #667eea;
    border: 2px solid #667eea;
}

.paste-btn:hover {
    background: #667eea;
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(102, 126, 234, 0.3);
}

.decrypt-btn {
    flex: 1;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.decrypt-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(102, 126, 234, 0.4);
}

.paste-btn:active,
.decrypt-btn:active {
    transform: translateY(0);
}

.paste-btn:disabled,
.decrypt-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.loading {
    text-align: center;
    padding: 40px;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

@keyframes spin {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}

.error-message {
    background: #fee;
    border: 2px solid #f88;
    border-radius: 8px;
    padding: 15px;
    color: #c33;
    margin-bottom: 20px;
}

.image-display {
    min-height: 200px;
    border: 2px dashed #ddd;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.image-display.has-image {
    border-style: solid;
    border-color: #667eea;
}

.image-display img {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
}

.placeholder {
    color: #999;
    font-style: italic;
}

footer {
    background: #f8f9fa;
    padding: 20px;
    text-align: center;
    color: #666;
    font-size: 0.9rem;
}